Fundamentals of Nutrition & Metabolism

Question 1

What is the length range for the small bowel in adults?

Answer 1

400 to 800 cm

Question 2

(T/F) <100 cm without colon requires TPN

Answer 2

TRUE

Question 3

(T/F) <50 cm with colon requires TPN

Answer 3

TRUE

Question 4

(T/F) The small bowel correlates with weight.

Answer 4

FALSE It correlates with height, shorter length seen in women.

Question 5

Where does absorption primarily occur for each vitamin:

• Vitamin K
• Vitamin B1
• Vitamin A
• Vitamin B12

Answer 5

• Vitamin K: Jejunum
• Vitamin B1 (thiamine): Proximal small intestine, especially jejunum
• Vitamin A: Upper SI
• Vitamin B12: Mostly ileum

Question 6

Accumulation of which trace element is associated with Wilson’s disease?

Answer 6

Copper

• Wilson’s disease is characterized by a genetic mutation of copper metabolism.
• Normal copper homeostasis is maintained via biliary excretion.
• Toxicity can occur with impaired biliary excretion

Question 7

(TRUE/FALSE) The acute phase response to injury and infection suppresses iron transport.

Part 2: What happens to serum iron levels? Serum ferritin levels?

Answer 7

TRUE.

• Serum iron levels decrease
• Serum ferritin levels increase
• The sequestering of iron into a storage form following injury and infection is thought to have several protective measures for the host. It reduces the availability of iron for iron-dependent microorganism proliferation and may reduce the potential for free radical production and oxidative damage to cell membranes and DNA.

Question 8

Explain enterohepatic circulation.

Answer 8

Refers to the circulation of bile acids, bilirubin from the liver to the bile, followed by entry into the SI, absorption by the enterocyte (in the intestine) and transport back to the liver.

Question 9

What is Cholecystokinin? What is its function in relation to enterohepatic circulation?

Answer 9

• It is an enteric hormone in the liver.
• Which induces the gallbladder to contract and release bile into the SI, when fat and protein is present in the duodenum

Question 10

The majority of dietary folate is reabsorbed via which mechanism?

What conditions may limit folate absorption?

Answer 10

Enterohepatic circulation.

• Dietary folate is converted to monoglutamate by jejunal enzymes for entry into the intestinal cell. It undergoes further reduction before entry into the portal circulation for reabsorption via enterohepatic circulation.

Conditions that may limit folate absorption?

• Zinc deficiency
• Chronic alcohol consumption
• Changes in jejunal pH
• Impaired bile secretion

Question 11

Explain the function of choline.

Answer 11

Required for lipid transport and metabolism.

• Used as a treatment for hepatic steatosis.
• Low plasma choline levels in long-term PN patients have been associated with elevated liver aminotransferase concentrations. Investigations reported that steatosis resolved following choline supplementation.
• Currently, PN admixtures do not contain choline.

Question 12

Name 3 examples of monosaccharides:

Options: Galactose, sucrose, glucose, maltose, fructose, lactose

Answer 12

1. Glucose
2. Fructose
3. Galactose

Question 13

What is phosphofructokinase?

Answer 13

Rate-limiting enzyme of glycolysis, which is inhibited when ATP is abundant.

Question 14

Why is the inhibition of phosphofructokinase important when ATP is abundant during glycolysis?

Answer 14

Allows the cell to divert glucose to be stored as glycogen

When ATP is limited, phosphofructokinase is activated.

Glycolysis = Breakdown of glucose

Question 15

Which two places is glycogen predominantly stored?

Answer 15

Liver

Skeletal Muscle

Question 16

What measurement is reflective of the functional or long-term status of SELENIUM?

Answer 16

Plasma glutathione peroxidase.

• Deficiency: <10.5 U/mL erythrocytes
• Status can also be assessed by determining the selenium level in whole blood, plasma, serum, or erythrocytes.
• Plasma levels of greater than 100mcg/L = Adequate levels

Question 17

What measurement does serum ceruloplasmin measure?

Answer 17

Copper status

Question 18

Explain the function of CHROMIUM.

Answer 18

Chromium potentiates the action of insulin and is important in glucose, protein, and lipid metabolism.

Chromium deficiency impairs glucose and AA use which may result in HYPERGLYCEMIA.

Question 19

What is a common clinical sign/symptom of vitamin D toxicity?

Answer 19

Soft tissue calcification (may occur in lungs and cardiovasculature).

Other signs: confusion, psychosis, tremor, hypercalcemia, and hypercalciuria

Question 20

What are common clinical signs/symptoms of vitamin D deficiency?

Answer 20

• Hypocalcemia
• Osteomalacia
• Tetany
• Osteoporosis

Question 21

What are some effective treatments in gastric phytobezoars?

Answer 21

• Flushing with Cola
• Enzymatic therapy with cellulase
• Surgical removal

Specifically, treatment with PAPAIN (meat tenderizer) should be avoided because it breaks down normal tissue and is associated with peptic ulcer disease, esophagitis, and gastritis.

Question 22

(TRUE/FALSE)

Fiber and medications can be flushed together through the feeding tube.

Answer 22

FALSE.

Should be spaced apart.

Never manipulate the feeding bag system due to risk of microbial growth through touch contamination

Question 23

Explain the Swinamer Equation.

Answer 23

Uses body surface area in addition to physiological variables to predict RMR (resting metabolic rate).

This equation has been found to predict RMR in about 55% of patients.

Question 24

Name some impacts that underfeeding has on critically ill patients.

Answer 24

Increases:

• Infections
• Complications
• Days on antibiotics
• Days on the ventilator

Question 25

Name some impacts overfeeding has on critically ill patients.

Answer 25

Negative effects:

• Hyperglycemia
• Liver dysfunction
• Fluid overload
• Respiratory compromise
• Increased CO2 production
• Lipogenesis

Question 26

(FILL IN THE BLANK)

[Insoluble/Soluble] fiber has stool softening effect resulting in faster transit time and more frequent bowel movements which provides relief from constipation.

[Insoluble/Soluble] fiber is fermented in the distal intestines and increases intestinal mucosal growth and promotes water and sodium absorption.

Answer 26

1. Insoluble fiber
2. Soluble fiber

Question 27

What is the approximate half-life of albumin?

Answer 27

20 days

Question 28

What is the approximate half-life of serum prealbumin?

Answer 28

2-3 days

Question 29

Define metabolic acidosis.

Answer 29

Metabolic acidosis:
pH < 7.35, decreased HCO3-, hyperventilation = dec pCO2

Causes:
H Hyperalimentation/TPN/EN
A Acetazolamide
R Renal Tubular Acidosis (bicarb rich renal loss)
D Diarrhea (bicarb rich fluid loss)
U Ureterostomies
P Pancreatic fistulas (GI loss)

M Methanol
U Uremia
D DKA/Alcoholic KA/Starvation KA
P Paracetamol, acetaminophen, phenformin/paraldehyde
I Iron, Isoniazid, Inborn errors
L Lactic acidosis
E Ethanol, Ethylene glycol
S Salicylates, ASA, aspirin

hyperparathyroidism, hypoaldsteronism)
* Ingestion of ammonium chloride or PN containing chloride salts

Question 30

Explain the chemical structure of fatty acids.

Answer 30

Molecules with an acidic carboxyl group at one end followed by a long chain of hydrogenated hydrophobic carbon atoms. Each FA is chemically characterized by the number of carbon atoms and double bonds present.

Question 31

How long are:

• Short-chain FAs
• Medium-chain FAs
• Long-chain FAs
• Very long-chain FAs

Answer 31

• SCFAs (2-4 carbons)
• MCFAs (6-12 carbons)
• LCFAs (14-18 carbons)
• Very long-chain (20 carbons or more)

Question 32

What type of FA is butyric acid?

Answer 32

SCFA (has 4 carbons)

Question 33

What type of FA is lauric acid?

Answer 33

MCFA (has 12 carbons)

Question 34

What type of FA is stearic acid?

Answer 34

LCFA (has 18 carbons)

Question 35

Explain the basic structure of a triglyceride.

Answer 35

Glycerol backbone with 3 FA molecules attached via an ester linkage.

Question 36

Triglycerides that require bile acids to facilitate enzymatic digestion and absorption contain FAs that are typically how long?

Answer 36

14 carbons in length.

The overwhelming majority of enteral dietary lipids (~90%) are ingested in the form of triglycerides. FAs of up to 10 carbons in length and glycerol can be absorbed DIRECTLY via the villi of the intestinal mucosa.

Long-chain triglycerides require bile salts for both enzymatic digestion and the formation of micelles.

Question 37

Where does the oxidation of FAs for ATP production occurs…?

Answer 37

Cells that contain mitochondria.

• Mitochondria are organelles found in most eukaryotes whose primary function is to generate APT via oxidative phosphorylation, the major source of cellular energy.
• FAs are transported into the mito. membrane and through the beta-oxidation pathway the FA is degraded and released as ATP.

Question 38

(TRUE/FALSE)

Red blood cells DO contain mitochondria in their cytoplasm.

Answer 38

FALSE

RBCs rely on the metabolic pathway of glycolysis for ATP for energy.

Question 39

What do both linoleic acid and alpha-linolenic acid require to enter the mitochondria?

Answer 39

L-carnitine

Question 40

Explain the breakdown of water in the body.

• Intracellular
• Extracellular
• Transcellular

Answer 40

TBW (total body water is 50-60% of body weight; broken down into 3 compartments on front).

• ICF = 2/3
• ECF = 1/3
  
  • Intravascular space = 1/4
  • Interstitial space = 3/4

Question 41

What is the best treatment for mild hypercalcemia? Severe hypercalcemia?

Answer 41

• Mild: Usually responds to hydration and ambulation; requiring no further intervention.
• Severe: Initially treated with saline hydration to correct volume depletion; then furosemide after hydration to enhance renal calcium excretion. HD may be necessaary

Question 42

Absorption of large polypeptides, oligopeptides, and free AAs takes place in the?

Answer 42

Small intestine.

-HCL secreted by the parietal cells of the stomach denatures the protein and makes it more susceptible to enzymatic action. Converts the inactive pepsinogen to active pepsin. Pepsin activates other pepsinogen molecules or hydrolyzes specific peptide bonds into end products of large polypeptides, oligopeptides, and free AAs. This mixture known as acid chyme passes into the duodenum where the majority of protein digestion takes place.

Question 43

When determining nitrogen balance, urea accounts for what percentage of total urine nitrogen losses?

Answer 43

80%.

-Urinary urea nitrogen concentration is affected by stress and increased urinary excretion of non-urea nitrogen.

Question 44

Supplemental arginine is considered therapeutic for what?

Answer 44

Immune function and wound healing.

-Supplementation with arginine in the critically ill septic patient population remains controversial.

Question 45

Transformation of free LCFAs into acylcarnitines and transport into the mitochondria, requires what?

Answer 45

Carnitine.

• It is a trimethyl AA similar in structure to choline
• Primary deficiency is rare, it has been documented in preterm infants and chronic renal failure.

Question 46

Which organ is key for protein metabolism? Why?

Answer 46

Liver because of its high capacity for uptake and metabolism of aaS.

• About 57% of the AAs extracted by the liver are either oxidized or used to synthesize plasma proteins.

Question 47

How does soluble fiber control diarrhea?

Answer 47

Soluble fiber has the ability to increase sodium and water absorption via its fermentation byproducts (SCFAs).

Question 48

What are two symptoms of abdominal discomfort?

Answer 48

Bloating and flatulence

Question 49

How does insoluble dietary fiber regulate normal defecation?

Answer 49

Increasing stool weight and bulk.

Question 50

Consumption of soluble fiber contributes to lower what?

Answer 50

Total cholesterol and LDL cholesterol.

• Does not change or lower HDL cholesterol levels
• May result in a small decrease in plasma glucose and A1C.

Question 51

(TRUE/FALSE)

Soluble fiber lowers the risk of developing colon cancer and reducing the recurrence of adenomas.

Answer 51

FALSE

Currently no clear evidence.

Question 52

During long-term starvation, what is the main energy source?

Answer 52

Fat acid oxidation.

• Fat tissue becomes the main energy source for nearly all tissues.
• After 14 days of fasting, adipose tissue can provide more than 90% of daily energy requirements.
• Remember: high glucagon concentrations promote FA oxidation

Question 53

Sodium-glucose transporter 1 (SGLT-1) transports which two substrates into the enterocytes from the intestinal lumen?

Does this require energy?

Answer 53

1. Glucose
2. Galactose

Yes, energy is provided by hydrolysis of ATP; therefore, is an active transport system.

Question 54

Which 2 water-soluble vitamins do not require Na+ co-transporters for absorption?

Answer 54

1. Vitamin B12
   
   1. Requires intrinsic factor (secreted by parietal cells in the stomach) for absorption, taken up by receptors in the distal ileum
2. Folic Acid
   
   1. Absorbed by a carrier-mediated process, primarily in the proximal part of the small intestine.

Question 55

How are MCTs absorbed?

Answer 55

They are water-soluble, hydrolyzed and pass through the enterocytes directly into the portal circulation

Question 56

(TRUE/FALSE)

MCTs require the formation of micelles or bile salts for absorption.

Answer 56

FALSE.

They are water soluble

Question 57

Mucosal atrophy that accompanies bowel rest may result from an absence of what substrate?

Answer 57

Glutamine, the principal metabolic fuel for intestinal cells

• Atrophic changes during bowel rest have been decreased with glutamine-enriched parenteral nutrition.

Question 58

What are symptoms of diarrhea, bloating, and flatulence after ingestion of sugar caused by?

Answer 58

Deficiency of brush border oligosaccharidases

• This deficiency allows osmotically active undigested oligosaccharides to cause a shift of water into the intestinal lumen
• Resulting in increased pressure increases further when colonic bacteria act on remaining oligosaccharides, thus increasing the number of osmotically active particles.
• Formation of CO2 and H2 from disaccharides further increase symptoms.

Question 59

Where does the majority of fat digestion occur?

Answer 59

Duodenum (with pancreatic lipase)

• Begins in the mouth (lingual lipase, ~10%) and stomach (gastric lipase, small amount)

Question 60

What is the role of bile acids in fat digestion?

Answer 60

Act as emulsifiers

Question 61

What is pancreatic exocrine deficiency?

Answer 61

The pancreas does not provide the digestive enzymes or they do not work normally

• Symptoms: diarrhea, abdominal pain/distention/bloating/cramps/flatulence/weight loss
• Treatment: Pancreatic enzyme replacement therapy

Question 62

What AA is conditionally essential and also a primary fuel source for enterocytes?

Answer 62

Glutamine

• Most abundant AA in the body, and vital fuel for rapidly dividing cells
• In some conditions: trauma, sepsis and exercise, the body’s glutamine requirement exceeds the rate of synthesis
• Decreased levels are associated with intestinal mucosal atrophy, impaired immune function, and decreased protein synthesis

Question 63

What is the average nitrogen content of protein? Calculation?

Answer 63

Has been determined to be 16%

• To calculate nitrogen content of a protein in a PN solution:
  
  • Total grams of protein x 0.16 OR
  • Total grams of protein / 6.25

Question 64

What is the protein recommendation for critically ill patients with trauma? What are two exceptions? What is their recommendation?

Answer 64

1.5 to 2.0 g/kg/day

Exceptions:

• CRRT & BMI > 30 should get 2.0 to 2.5 g/kg/day
• For BMI 30+: use IBW

Question 65

What are two areas of the body that require a constant supply of glucose?

Answer 65

Brain and RBCs

Question 66

When does glycogenolysis start during fasting? When are stores depleted?

When is gluconeogenesis started? When does the body switch substrates after this?

Why does the body switch away from gluconeogenesis?

Answer 66

Glycogenolysis (breakdown of hepatic glycogen stores) begins 2-3 hours of fasting; with stores depleted after 24 hours.

Gluconeogenesis (from AA substrate) begins within 4-6 hours after the last meal. After 2 days of starvation, the brain switches its fuel source from glucose to ketone bodies.

The liver converts free FAs to ketone bodies. The adaptation of starvation with a ketone-based fuel system minimizes gluconeogenesis and further protein breakdown.

Question 67

What are the 3 organs in the body that have the necessary enzymes for gluconeogenesis?

Answer 67

1. Liver (main site)
2. Small intestine (under certain conditions)
3. Kidney (under certain conditions)

Question 68

Explain AMDR. What 3 nutrients have established AMDRs?

Answer 68

AMDR = Acceptable Macronutrient Distribution Range

• A range of intake for a particular energy source that is associated with reduced risk, rather than assisting in the treatment, of chronic disease.
  
  • Omega-3
  • Omega-6
  • Total Fat

Question 69

Explain Tolerable Upper Intake Level.

Answer 69

The highest level of daily nutrient intake that is likely to pose no risk of adverse health effects to almost all individuals in the general population.

Question 70

Explain EAR.

Answer 70

EAR = Estimated Average Requirement.

• The average daily nutrient intake level estimated to meet half the needs of healthy individuals in a particular life stage and gender group.

Question 71

What oils are included in commercial enteral formulas to provide a good source of linoleic and alpha-linolenic acids?

Answer 71

• Corn
• Soybean
• Safflower
• Canola oils

Question 72

What is the prominent clinical change seen with EFAD? What are other implications?

Answer 72

Dry, scaly rash

• Increased susceptibility to infection
• Impaired wound healing
• Weight loss
• Immune dysfunction

Question 73

(TRUE/FALSE)

The active transport of sodium out of the cell provides the energy for glucose transport.

Answer 73

TRUE

The transport of sodium out of the cell maintains the concentration gradient needed for sodium to shuttle more glucose into the mucosal cells.

Question 74

Explain pellagra.

Answer 74

Niacin deficiency disease; presents as the 3 ‘Ds’

• Dermatitis
• Diarrhea
• Dementia

Food Sources include: meat, fish, poultry, enriched and fortified breads, and cereals

Question 75

What is ursodiol?

Answer 75

Ursodiol (ursodeoxycholic acid) is a form of bile acid that may potentially improve fat absorption.

Therefore, it facilitates absorption of fat.

Question 76

What does sulfamethoxazole/trimethoprim induce?

Answer 76

Hyperkalemia by impairing renal potassium excretion.

Question 77

What is the first-line therapy for hyperkalemic emergencies?

Answer 77

Calcium gluconate 1-2 grams IV over 10 minutes, with an effective onset time of 1-2 minutes.

Should be given to symptomatic patients or those with ECG changes to restore membrane excitability to normal.

Other options, but limited:

• HD (access limited)
• Insulin gtt with dextrose (15-45 min onset time)
• Lasix (5-15 min onset time)

Question 78

What acid-base disorder is likely to occur with acute severe diarrhea?

Answer 78

Metabolic acidosis

• Diarrhea induces GI losses of bicarbonate

Question 79

What are the most serious complications of hyperphosphatemia?

Answer 79

Metastatic and vascular calcification of non-skeletal tissues

Question 80

Define metabolic alkalosis.

Answer 80

Characterized by an elevation in pH, an increase in [serum HCO3], and compensatory HYPOventilation, resulting in a RISE of PCO2

Common Causes:

• Loss of gastric acid (HCl) as a result of V or NG suction
• Loss of intravascular volume and chloride as a result of diuretic use
• Overzealous tx metabolic acidosis of bicarbonate OR an excess of acetate in PN solutions (which is metabolized to bicarb with a normally functioning liver)
• Some renal impairment must exist for this condition to occur

Tx: Treatment of the underlying cause; aggressive K repletion when hypokalemia is present in hyperaldosteronism

*

Question 81

Define respiratory acidosis.

Answer 81

Characterized by reduced pH, an elevation in PCO2, and a variable increase in the [serum HCO3].

• Almost always results from a decreased effective alveolar ventilation, not an increase in CO2 production

Causes:

• Central depression of respiration
• Drugs (opioids, sedatives)
• Stroke
• Head injury
• Sleep apnea
• Airway or pulmonary abnormalities (airway obstruction, asthma, COPD, severe pulmonary edema, ARDS, pneumothorax, smoke inhalation)
• Neuromuscular abnormalities (Brainstem or cervical cord injury, Guillain-Barre syndrome), myasthenia gravis, MS)
• Obesity HYPOventilation
• Mech vent HYPOventilation
• PN/EN OVERfeeding

Question 82

Define respiratory alkalosis:

Answer 82

Characterized by elevated pH, a decrease in PCO2, and a variable reduction in [serum HCO3]. Occurs when effective alveolar ventilation is increased beyond the level necessary to eliminate metabolically produced CO2.

Common Causes:

• Central simulation of respiration
• Anxiety, pain, fever
• Brain tumors
• Vascular accidents
• Head trauma
• Pregnancy
• Catecholamines, Salicylate toxicity
• Peripheral stimulation
• Pulmonary embolus
• Asthma
• High altitudes
• PNA
• Pulmonary edema
• Severe anemia
• Mech vent HYPERventilation
• Hepatic encephalopthy

Question 83

Glycolysis occurs in the ____ state

Answer 83

Fed

Question 84

The breakdown of glucose into pyruvate to produce energy

Answer 84

Glycolysis

Question 85

End product of glycolysis

Answer 85

pyruvate

Question 86

Endogenous formation of glucose from non carbohydrate sources

Answer 86

Gluconeogensis

Question 87

What are common substrates for gluconeogenesis

Answer 87

fat, amino acids, lactic acid

Question 88

What is the purpose of gluconeogenesis

Answer 88

to maintain plasma glucose during the fasted state and hypoglycemia

Question 89

Where does gluconeogenesis occur

Answer 89

the liver , kidneys and small intestines

Question 90

Gluconeogenesis occurs in the ___ state

Answer 90

fasted

Question 91

Which counterregulatory hormones are involved in gluconeogensis

Answer 91

epinephrine, norepinephrine, cortisol, glucagon, thyroid hormone, growth hormone

Question 92

what are the precursors for gluconeogenesis

Answer 92

lactic acid, alanine or glutamine amino acids and glycerol from broken down triglycerides

Question 93

what is the preferred amino acid for gluconeogenesis

Answer 93

alanine (it converts into oxaloacetate from malate)

Question 94

Gluconeogenesis will start within ____ ____ when there is no glucose

Answer 94

4-6 hours

Question 95

How long until glycogen is depleted in a 70 kg male during starvation

Answer 95

24 hours

Question 96

what are the fasting hormones (catabolic)

Answer 96

Glucagon, glycogenolytic, gluconeogenic, lipolytic and ketogenic hormones. Also released during stress and infection

Question 97

Lipolysis

Answer 97

catabolism of the storage form of fat

Question 98

Lipolysis happens during a ____ state

Answer 98

fasted state/ stress

Question 99

Which hormone suppresses lipolysis

Answer 99

insulin

Question 100

Lipolysis is triggered by the hormone ____ when blood glucose is ____

Answer 100

glucagon, low

Question 101

Lipolysis is inhibited by the hormone ____ when blood glucose is ____

Answer 101

insulin, high

Question 102

Branched Chain Amino Acids are stored in the ____state

Answer 102

Fed

Question 103

which amino acid is used in gluconeogenesis

Answer 103

alanine

Question 104

what is the role of amino acids in the kidney and brain

Answer 104

gluconeogenic amino acids that are made into glucose during gluconeogenesis. Works for the brain as neurotransmitters, pre-cursors to catecholamines etc.

Question 105

an antioxidant derived from amino acids that plays a role in the development of arginine and nitrous oxide for preventing oxidative damage

Answer 105

glutathione

Question 106

the primary substrate for gluconeogenesis in starvation

Answer 106

Protein

Question 107

ketogenesis will start within ________ ______ during starvation

Answer 107

48 hours

Question 108

Glucagon is released in response to _____ BG as well as _____ and _____

Answer 108

low blood glucose, stress, sepsis

Question 109

Amino acid needed for transport and metabolism of long chain fatty acids into the matrix of the mitochondria for beta oxidation

Answer 109

carnitine

Question 110

_____deficiency leads to impaired fatty acid oxidation which can increase the chance for hepatic steatosis

Answer 110

carnitine

Question 111

Insensible water losses come from primarily the ____ and ___

Answer 111

skin and lungs

Question 112

how long is the small intestine

Answer 112

350-600 centimeters

Question 113

how much fluid does the duodenum secrete

Answer 113

9 liters (2 liters from PO, 7 liters of gastric fluid)

Question 114

role of the ileocecal valve

Answer 114

Prevents backsplash of colon contents into the jejunum. Closes when there is an increase in colonic pressure

Question 115

complications of ileocecal valve removal

Answer 115

decreased B12 absorption, decreased bile salt reabsorption, rapid GI movement of the small bowel contents into the colon which can cause malabsorption

Question 116

______ are partially digested in the large bowel then consumed by gut bacteria where it is fermented and made into short chain fatty acids for energy for the colonocytes

Answer 116

soluble fiber

Question 117

short chain fatty acids are derived from which type of fiber

Answer 117

soluble fiber

Question 118

which type of fiber adds bulk to stool to soften it

Answer 118

insoluble fiber

Question 119

conditions that cause gut dysbiosis

Answer 119

obesity, diabetes, IBD/IBS, cancer

Question 120

where are sodium and water absorbed most efficiently

Answer 120

colon and ileum

Question 121

where is fat primarily absorbed

Answer 121

duodenum / proximal jejunum

Question 122

Primary absorption site of iron

Answer 122

duodenum

Question 123

primary absorption site of manganese and folic acid

Answer 123

jejunum

Question 124

Medium Chain Triglycerides are used during fat malabsorption because

Answer 124

they don’t have to be formed into micelles, they are water soluble and go right into circulation and don’t require bile salts.

Question 125

Benefits of short chain fatty acids

Answer 125

inhibit cholesterol formation
improve splanchnic circulation
enhances immunity helper T cells
inhibits pathogen growth
decreases luminal pH
lowers bile solubility

Question 126

Primary absorption site of vitamin B 12

Answer 126

ileum

Question 127

where are the majority of water, electrolytes and minerals absorbed

Answer 127

colon and small intestine

Question 128

potassium and bicarobonate are secreted into the

Answer 128

colon

Question 129

water follows sodium via this mechanism

Answer 129

osmosis

Question 130

ileal or colonic losses from diarrhea or high output fistulas can lead to

Answer 130

hypokalemia, acidemia from loss of bicarbonate

Question 131

most dietary iron is in the ______ form which is poorly absorbed in the gut

Answer 131

Ferric Fe2+

Question 132

In order for iron to be absorbed, it has to change into the ______ form

Answer 132

Ferrous Fe3+

Question 133

Which vitamin aids in the reduction of the Ferric Form (Fe2) of Iron to the Ferrous form (Fe3) of iron for easier absorption

Answer 133

Vitamin C (ascorbic acid)

Question 134

What can be added to foods to enhance the absorption of iron in non-heme foods

Answer 134

Vitamin C

Question 135

what amino acid provides the main fuel for enterocytes

Answer 135

glutamine

Question 136

the absence of this amino acid can lead to mucosal atrophy

Answer 136

glutamine

Question 137

site of primary protein digestion

Answer 137

duodenum

Question 138

which enzymes digest protein

Answer 138

pepsin/pepsinogen when mixed with chyme

Question 139

what amino acids are most rapidly absorbed

Answer 139

branched chain amino acids and essential amino acids

Question 140

the primary energy source for the GI tract is ________ which has trophic effects and helps with immune function

Answer 140

glutamine

Question 141

there is an increased need for what amino acid in critical illness

Answer 141

glutamine

Question 142

what is the most abundant amino acid

Answer 142

glutamine

Question 143

detriments of inadequate glutamine

Answer 143

GI mucosal atrophy, impaired immune function, increased risk for sepsis/bacterial translocation

Question 144

which amino acids are important for the small intestine

Answer 144

glutamine and aspartate

Question 145

what function do amino acids provide the liver

Answer 145

synthesis of plasma proteins: albumin, pre albumin, transferrin, clotting factors (fibrinogen/prothrombin)

Question 146

The amino acid alanine is used for what in the liver

Answer 146

gluconeogenesis

Question 147

Bile drains into the

Answer 147

duodenum

Question 148

a disturbance of the lymphatic system in which fluid is incorrectly distributed and does NOT respond to diuretics

Answer 148

lymphedema

Question 149

Recommended sodium dosage provides ___ to ___ mEq/kg of sodium

Answer 149

1-2 mEq/kg

Question 150

normal serum sodium range

Answer 150

135-145

Question 151

when serum sodium is low, cells are known as ______tonic

Answer 151

hypotonic

Question 152

primary sodium losses occur from

Answer 152

NGT suction, fistula drainage, adrenal insufficiency

Question 153

when there are increased solutes in the blood circulation, water shifts from inside of the cell to outside of the the cell resulting in which type of hyponatremia

Answer 153

hypertonic hyponatremia

Question 154

Primary IV treatment of hypovolemic hyponatremia

Answer 154

normal saline

Question 155

Causes of hypovolemic hyponatremia

Answer 155

Third Spacing (SBO, low albumin)
Diarrhea, Vomiting, NGT suction (GI losses)
Diuretics

Question 156

primary treatment of hypervolemic hyponatremia

Answer 156

Water restriction

Question 157

causes of hypervolemic hyponatremia

Answer 157

CHF, Cirrhosis, TURP

Question 158

primary treatment of isovolemic hyponatremia

Answer 158

water restriction

Question 159

causes of isovolemic hyponatremia

Answer 159

too much IVF, water intoxication, diuretics, SIADH, drugs

Question 160

the hormone released by the pituitary gland that tells your kidney how much water to conserve to maintain blood pressure by concentrating the urine

Answer 160

Anti Diuretic Hormone

Question 161

When your body has high levels of ADH, the kidneys re-absorb too much water. Total body water will increase and becomes hypo-osmolar and sodium decreases which is known as

Answer 161

SIADH (symptom on inappropriate diuretic hormone)

Question 162

Etiologies of SIADH

Answer 162

malignant tumors, head trauma, meningitis, schizophrenia meds, post surgical

Question 163

Treatment for SIADH

Answer 163

water restriction , sodium supplementation

Question 164

Acute hypotonic hyponatremia (acute water intoxication)

Answer 164

Sodium <125mEq/L causing headache, nausea, confusion. Na <110 mEq/L can cause seizure, coma or death

Question 165

Sodium Deficit Calculation

Answer 165

Normal Na - Current Na x body weight in kg x % body water

Question 166

Give no more than ___ free water deficit a day or > mEq/day when restricting sodium

Answer 166

1/2 of the free water deficit or 6-12 mEq/Day

Question 167

a condition of cerebral edema (which can be deadly) in which too much sodium is given too much at one time is known as

Answer 167

osmotic myelinolysis

Question 168

Hypertonic saline (3%) is used to treat

Answer 168

severe hyponatremia when a patient is confused or obtunded

Question 169

when giving hypertonic saline, serum Na should be checked how often

Answer 169

every 1-2 hours

Question 170

Don’t correct Na more than ____ to ____ a day

Answer 170

6-12 mEq/day

Question 171

How much sodium would you replete for a 70kg male with a serum sodium of 120mEq/L with headache and confusion

Answer 171

126-120 x .6 x 70 kg = 252 mEq sodium

Question 172

symptoms of hypernatremia

Answer 172

lethargy, confusion, twitching , stupor, coma

Question 173

failure of the central brain to release ADH or failure of the kidneys to respond to ADH is known as

Answer 173

Diabetes Insipidus

Question 174

Symptoms of diabetes insipidus

Answer 174

polyuria, polydypsia,hypernatremia , retained sodium

Question 175

is sodium high or low in diabetes insipidus

Answer 175

high

Question 176

treatment of diabetes insipidus

Answer 176

hypotonic fluids 0.2 or 0.45% NaCl, volume restriction, sodium restriction

Question 177

the major intracellular electrolyte

Answer 177

potassium

Question 178

normal serum range of potassium

Answer 178

3.5-5

Question 179

typical IV dose of potassium ins mEq/kg/day

Answer 179

1-2 mEq/kg/day

Question 180

causes of hyperkalemia

Answer 180

acidosis (Hydrogen moves out of the blood to become less acidic and into the cell, so potassium will move out of the cell into the blood), renal failure, traumatic blood draw (false positive), hemolysis, burns, crushing syndrome, NSAIDS, K sparing diuretics, tacrolimus

Question 181

symptoms of hyperkalemia

Answer 181

EKG changes, decreased heart rate, arrthymias, high T waves, wide QRS, heart block, atrial systole, cardiac arrest, muscle cramping/twitching, weakness

Question 182

What is the first step of potassium correction to stabilize the heart

Answer 182

calcium gluconate

Question 183

What is the second step of potassium correction to shift potassium back into the cell

Answer 183

sodium bicarb, 100mL 50% dextrose, 10 units of insulin

Question 184

Other methods to reduce potassium in hyperkalemia after calcium gluconate and correction of acidosis

Answer 184

dc or decrease supplemental potassium, use K sparing diuretics like Lasix, dialysis

Question 185

symptoms of hypokalemia

Answer 185

weakness, lethargy, constipation, arrhythmia, psychosis, post op ileus, flat T waves

Question 186

causes of hypokalemia

Answer 186

diarrhea, high urine output, metabolic alkalosis, increased amounts of insulin, catecholamines, furosemide, thiazide diuretics, sorbitol, refeeding syndrome

Question 187

IV forms of potassium

Answer 187

potassium chloride, potassium acetate, potassium phosphorous

Question 188

what type of potassium is preferred in acidosis

Answer 188

potassium acetate

Question 189

potassium takes ___ hours to normalize

Answer 189

2 hours

Question 190

Avoid providing IV potassium with ______ as glucose/insulin will increase forcing potassium into the cell and worsen hypokalemia

Answer 190

dextrose

Question 191

you must correct ______ to correct potassium

Answer 191

magnesium

Question 192

normal serum mangesium

Answer 192

1.8-2.8

Question 193

magnesium is primarily absorbed in the

Answer 193

jejunum/ileum

Question 194

magnesium is primarily excreted by the

Answer 194

kidneys

Question 195

symptoms of hypomagnesemia

Answer 195

low potassium, tetany, decreased insulin sensitivity, arrhythmias

Question 196

causes of hypomagnesemia

Answer 196

refeeding syndrome, decreased intake/absorption, prolonged magnesium free PN, alcoholism, ileostomy, short bowel syndrome, loop diuretics, DKA

Question 197

what route of magnesium replacement is preferred

Answer 197

IV, oral can cause GI upset

Question 198

max infusion rate of magnesium

Answer 198

1 gram per hour (less in renal failure)

Question 199

replace magnesium with ____ in order to decrease risk of cardiac arrhythmias

Answer 199

potassium

Question 200

causes of hypermagnesemia

Answer 200

chronic kidney disease and high magnesium intake/provision in EN/PN

Question 201

symptoms of hypermagnesemia

Answer 201

nausea, diaphoresis, flushing/heat flash, bradycardia, hypotension

Question 202

IV treatment for hypermagnesemia

Answer 202

calcium chloride or calcium gluconate

Question 203

medication treatment for hypermagnesemia

Answer 203

loop diuretics

Question 204

normal calcium range

Answer 204

8.6-10.2

Question 205

what hormones control calcium

Answer 205

parathyroid hormone, vitamin D and calcitonin

Question 206

the release of PTH is signaled by low _____ to increase _________, __________ and _________

Answer 206

calcium ; bone resorption, renal conservation, absorption in the gut

Question 207

Vitamin D increases calcium by

Answer 207

increasing gut absorption of calcium

Question 208

Calcitonin is signaled by ________ calcium to ______ osteoclast function

Answer 208

high calcium to decrease osteoclast formation to stop releasing calcium

Question 209

Ionized Calcium normal range

Answer 209

1.2-1.3 mmol/L

Question 210

what is the most accurate way to measure serum calcium

Answer 210

ionized calcium

Question 211

ionized calcium is not affected by _____-

Answer 211

albumin

Question 212

Calcium correction for hypoalbuminemia

Answer 212

4- serum albumin x .8 + serum calcium

Question 213

etiologies of hypocalcemia

Answer 213

low albumin, decreased vitamin D activity, hyperphosphatemia, decreased PTH, hypomagnesemia, citrate anticoagulation in CRRT, thyroidectomy, sepsis, rhabdomyolysis, blood transfusion, bisphosphonates, furosemide, calcitonin, phenytoin

Question 214

symptoms of hypocalcemia

Answer 214

decreased blood pressure, decreased myocardial contraction, decreased QT prolongation, extremity parenthesis, cramps, tetany

Question 215

preferred IV fluid to correct hypocalcemia

Answer 215

calcium gluconate or calcium chloride

Question 216

provide ____ to aid in calcium correction

Answer 216

magnesium

Question 217

oral forms of calcium repletion

Answer 217

calcium acetate, vitamin D supplements, calcium citrate, calcium carbonate (tums)

Question 218

causes of hypercalcemia

Answer 218

cancer, hyperparathyroidism, high vitamin D or A intake, chronic intake of milk, antacids or calcium supplements, lithium, TB, thiazide diuretics

Question 219

symptoms of hypercalcemia

Answer 219

fatigue, nausea, vomiting, constipation, anorexia, cardiac arrhythmia, bradycardia

Question 220

treatment of mild hypercalcemia

Answer 220

hydration and ambulation

Question 221

treatment of hypercalcemia in setting of malignancy

Answer 221

bisphosphonates

Question 222

treatment of severe hypocalcemia

Answer 222

lasix, hemodialysis, 1,000-1,500 mg elemental calcium, IV calcium chloride or calcium gluconate

Question 223

normal range of phosphorous

Answer 223

2.7-4.5

Question 224

functions of phosphorous

Answer 224

makes up bone, pH balance, makes up ATP, carbohydrate metabolism, part of 2.3-diphosphoglycerate on RBCs, muscle function, myocardial function and all cell function

Question 225

regulation of phosphorous

Answer 225

intestinal absorption, renal excretion, hormone regulation, bone resorption (deposition)

Question 226

causes of phosphorous shifts

Answer 226

carbohydrate/insulin, catecholamines and alkalosis

Question 227

symptoms of hypophosphorous

Answer 227

ataxia, confusion, paresthesia, hemolysis, refeeding syndrome

Question 228

etiologies of low phosphorous

Answer 228

alcoholism, critical illness, respiratory or metabolic acidosis, DKA treatment 2/2 insulin, high CHO in TPN especially if malnourished

Question 229

treatment of mild hypophosphorous

Answer 229

K Phos, Phos NaK

Question 230

treatment of symptomatic hypo phosphorous

Answer 230

IV K phos or IV Na Phos

Question 231

____mmol of phos = 4.4 mEq potassium

Answer 231

3

Question 232

causes of hyperphosphatemia

Answer 232

CKD, ESRD, trauma, hemolysis, rhabdomyolysis, respiratory metabolic acidosis, high dose phos containing enemas

Question 233

If a patient has excessive vomiting with bile they will have low

Answer 233

sodium and chloride

Question 234

gastric juice contains ____ to ___ mEq/L of chloride

Answer 234

120-160 mEq chloride

Question 235

bile contains ______ to ______ of sodium

Answer 235

120-170 mEq/L

Question 236

diarrhea contains _____ to _____ mEq/L of potassium

Answer 236

10-60

Question 237

if a patient has excessive diarrhea, they will be low in

Answer 237

potassium and sodium (and zinc!)

Question 238

if a patient has large volumes of NGT suction what could you expect in regards to electrolyte/acid base balance

Answer 238

decreased chloride, decreased sodium and metabolic alkalosis

Question 239

composition of lactated ringers

Answer 239

130 mEq sodium, 4 mEq potassium, 3 mEq calcium, 109 meQ chloride, 28 meQ bicarb will transform into acetate, lactate , 280 osmoles

Question 240

which IV fluid is compositionally comparable to the jejunum

Answer 240

lactated ringers

Question 241

composition of normal saline

Answer 241

154 mEq sodium 154 mEq chloride , 308 milliosmoles

Question 242

composition of D5W

Answer 242

Dextrose 5% per liter, water, 250 mOsm

Question 243

which IV fluid has the lowest osmolarity

Answer 243

D5W

Question 244

D5W + 0.45 NaCl

Answer 244

Dextrose, Water, 77 mEq sodium 77 mEq chloride, 405 milliosmoles

Question 245

which IVF has the highest osmolarity

Answer 245

D5W with 1/2 normal saline (0.45NaCl) with Potassium

Question 246

where are 90-95% of bile salts re absorbed

Answer 246

terminal ileum

Question 247

water and sodium are most efficiently absorbed here

Answer 247

ileum and colon

Question 248

catabolism of this macronutrient is most common in stress starvation

Answer 248

Fat (lypolysis)

Question 249

the gallbladder is stimulated by

Answer 249

cholecystekinin

Question 250

high insulin levels suppresses this form of metabolism

Answer 250

lipolysis (insulin increase indicates fed state)

Question 251

which enzyme starts the digestive process of carbs in the mouth

Answer 251

salivary amylase

Question 252

homeostasis of copper is driven by

Answer 252

excretion

Question 253

the majority of copper is absorbed by the

Answer 253

duodenum

Question 254

phytates, zinc, iron and large vitamin C doses interfere with ___ absorption

Answer 254

copper

Question 255

copper is excreted via

Answer 255

bile

Question 256

oxidation/reduction reactions, electron transfer, manganese oxidation glucose metabolism, and oxidation of ferrous to ferric form of iron are roles of

Answer 256

copper

Question 257

Copper deficiency inhibits ______ absorption

Answer 257

iron

Question 258

deficiency of copper causes _____ deficiency

Answer 258

iron deficiency anemia

Question 259

Iron needs to be reduced to the ferric state so it can bind to transferrin on the red blood cell. This is inhibited by ____ deficiency leading to iron deficiency anemia

Answer 259

copper

Question 260

copper deficiency causes _____ ____ anemia (type of RBC)

Answer 260

microcytic , hypochromic

Question 261

populations at risk for copper deficiency

Answer 261

bariatric surgery, intestinal surgery, diarrhea, malabsorptive disorders

Question 262

excessive copper can be secondary to _____ excretion leading to oxidative damage

Answer 262

impaired gallbladder (biliary)

Question 263

Wilson’s disease is caused by excess ______ in the liver, typically causing liver cirrhosis

Answer 263

copper

Question 264

hypopigmentation of the hair, Kayser Fleisher rings in the eyes, hypochromic microcytic anemia are symptoms of ____ deficiency

Answer 264

copper

Question 265

an overdose in zinc causes ______ deficiency

Answer 265

copper

Question 266

_____ medications decrease copper absorption

Answer 266

acid reducers as copper digestion relies on HCL From the stomach

Question 267

Copper deficiency is common in ______ disease and requires supplementation when anemic

Answer 267

Celiac disease

Question 268

Copper overload occurs with

Answer 268

parenteral nutrition 2/2 limited gall bladder stimulation for excretion

Question 269

manganese is excreted by the

Answer 269

bile

Question 270

this mineral is involved in the make up of metalloenzymes, arginase and pyruvate carboxylase

Answer 270

manganese

Question 271

populations at risk for manganese toxicity

Answer 271

long term TPN

Question 272

irritability, hallucinations, ataxia, and hepatic damage, Parkinson’s like symptoms, altered gait are all sings/symptoms of _____ toxicity

Answer 272

manganese

Question 273

the content of this mineral in food depends on soil levels

Answer 273

selenium

Question 274

thyroid alterations can occur in long term PN with out _____ supplementation

Answer 274

selenium

Question 275

hair/nail loss, peripheral neuropathy, tooth decay and fatigue can be symptoms of ___ toxicity

Answer 275

selenium

Question 276

selenium deficiency also concurs with ____ deficiency limiting thyroid function

Answer 276

iodine

Question 277

this micronutrient is taken up by the thyroid to synthesize thyroid hormones

Answer 277

iodinne

Question 278

what is the metabolically active form of thyroid hormone

Answer 278

T3

Question 279

goiters are symptoms of ___ deficiency

Answer 279

iodine

Question 280

increased TSH and depressed thyroid activity are results of ____ deficiency

Answer 280

iodine

Question 281

iodine isn’t available in PN formulations. The alternative method to provide iodine in long term PN patients is

Answer 281

antiseptic preparations on the skin

Question 282

this micronutrient is essential for glucose and lipid metabolism by mobilizing insulin

Answer 282

chromium

Question 283

hyperglycemia is a symptom of ____ deficiency (trace mineral)

Answer 283

chormium

Question 284

fluoride is primarily absorbed in the

Answer 284

stomach

Question 285

functions of fluoride include

Answer 285

bone mineralization, hardening of tooth enamel, protects calcified tissues from demineralization, inhibits dental carries

Question 286

teeth mottling, nausea/vomiting/diarrhea are all symptoms of ____ toxicity

Answer 286

fluoride

Question 287

absorption of molybdenum occurs in

Answer 287

the stomach

Question 288

molybedenum are excreted via the

Answer 288

kidneys

Question 289

ultra trace elements (lead, lithium, nickel, tin etc) are elements needed in less than _____ mg /day and have no ____ or _____ determined

Answer 289

RDA or AI’s

Question 290

now that vitamin K is added to the PN MVI, take caution with patients on this medication

Answer 290

Coumadin/Warfarin (monitor INR)

Question 291

Parenteral trace elements

Answer 291

selenium, copper, manganese

Question 292

in the setting of parenteral MVI/Trace element shortages, what is recommended

Answer 292

prioritize the most vulnerable

Question 293

a patient with mental status changes (dementia) , dermatitis and diarrhea may have this deficiency

Answer 293

niacin deficiency (Pellagra)

Question 294

manganese toxicity is common in long term PN because its route of excretion is

Answer 294

the gallbladder/bile

Question 295

_____ toxicity occurs with cholestasis (a long term complication of PN)

Answer 295

manganese

Question 296

extrapyramidal symptoms such as Parkinson’s like symptoms, muscle ridgitiy and tremors, and altered gait are symptoms of ____ toxicity

Answer 296

manganese

Question 297

the most common micronutrient toxicity in long term PN regardless of liver function is

Answer 297

hypermanganese

Question 298

if a patient exhibits cholestasis, limit these elements by providing ___ and ___ free trace elements in long term PN patients

Answer 298

manganese, copper

Question 299

supplementation of this element may help reduce hyperglycemia

Answer 299

chromium

Question 300

patients with significant GI losses including diarrhea are at risk for deficiency of this element

Answer 300

zinc

Question 301

in wounds, high ostomy output and excessive diarrhea supplement with this element

Answer 301

zinc

Question 302

serum zinc is not a reliable marker of zinc status because

Answer 302

it is bound to albumin which is widely available in the body

Question 303

zinc and copper will not compete for absorption in

Answer 303

IV doses in PN

Question 304

Case: A patient who is PN dependent with a daily output of 3L from his ileostomy, has recently increased BUN/Creatinine ration and a serum sodium of 131 mEq/L is at risk for what deficiencies. The increased BUN/Cr ratio is likely 2/2 ______. Hyponatremia is likely 2/2 ____ losses when fluid replacement doesn’t contain adequate NA. ______ supplementation is recommended to prevent deficiency as there is likely high losses from the ileostomy drainage

Answer 304

water, sodium,zinc
dehydration
GI losses
Zinc

Question 305

headaches and Parkinson’s like activity (extrapyramidal symptoms) are a result of ____ toxicity

Answer 305

manganese (sometimes zinc)

Question 306

if a patient with short bowel syndrome who has required PN for 2 years presents with dysgeusia, diarrhea and alopecia, they most likely are deficient in

Answer 306

zinc

Question 307

What are the monosaccharides?

Answer 307

Glucose, galactose, fructose

Question 308

Name 3 common disaccharides

Answer 308

Sucrose (1 glucose and 1 fructose)
Maltose (2 glucose moieties)
Lactose (1 glucose and 1 galactose)

Question 309

Are complex carbs water soluble or insoluble?

Answer 309

Insoluble with high molecular weights.

Question 310

What are oligosaccharides?

Answer 310

Polysaccharides containing fewer than 10 glucose units

Question 311

What are the straight chains in starch called?

Answer 311

Amylose

Question 312

What are the branched chains in starch called?

Answer 312

Amylopectin

Question 313

How do glucose and galactose enter enterocytes?

Answer 313

Through sodium-glucose transporter 1 (SGLT1), an adenosine triphosphate (ATP)-dependent active transporter

Question 314

Which protein transports fructose?

Answer 314

GLUT5 (glucose transporter 5)

Question 315

What are the 2 classes of glucose transport proteins?

Answer 315

The sodium dependent glucose transporters and the facilitative transporters

Question 316

Describe the function of facilitative transporters

Answer 316

Function as passive diffusions channels (channels dependent on the gradient of glucose concentration between extra- and intracellular compartments) and do not require sodium or ATP. Present in many different tissues

Question 317

Describe the function of sodium dependent glucose transporters

Answer 317

Involved in the active, ATP-dependent absorption of glucose from the intestinal lumen into cells. Also function in the reabsorption of filtered glucose in the proximal tubule of the kidney

Question 318

Where are the highest concentrations of GLUT1?

Answer 318

Endothelial (major part of the blood-brain barrier) and glial cells of the brain

Question 319

Which monosaccharides are transported by GLUT1?

Answer 319

Glucose and galactose

Question 320

Where is GLUT2 mainly located?

Answer 320

Liver, small intestine, and kidneys

Question 321

Describe the action of GLUT2 in the liver (1), kidneys (2), small intestine (3)

Answer 321

1. In hepatocytes, GLUT2 has a low affinity but high capacity for glucose, allowing quick equilibration of intracellular and extracellular glucose concentrations across the membrane during fasting and fed states.
2. GLUT2 transports the reabsorbed glucose back into the bloodstream from proximal tubular epithelia.
3. GLUT2 is important in the transepithelial transport of the absorbed glucose

Question 322

Where is the highest concentration of GLUT3?

Answer 322

The neuronal membranes of the brain

Question 323

Describe the action of GLUT3 in neuronal cells

Answer 323

Controls the rate of glucose entry into neuronal cells

Question 324

Where is GLUT4 mainly located?

Answer 324

Adipose (brown and white) and muscle (skeletal and cardiac) tissues. Mainly within the intracellular vesicles of these tissues but can be translocated to the cell surface in response to a rise in plasma insulin concentrations or muscle contraction

Question 325

Where is GLUT5 mainly located?

Answer 325

The apical membrane of the jejunum

Question 326

What is the formula that expresses the net chemical reaction of glucose catabolism?

Answer 326

C6H12O2 + 6O2 –> 6CO2 + 6H2O + Energy

Question 327

Where in the cell does glycolysis take place?

Answer 327

The cytoplasm

Question 328

Where in the cell does the TCA cycle take place?

Answer 328

Inside mitochondria

Question 329

Glucose absorption into which organs is dependent on insulin? Independent?

Answer 329

Skeletal muscle and adipose tissue glucose absorption is insulin dependent.
Liver, kidney, brain, other tissue glucose absorption is insulin independent.

Question 330

Name the substrates and major sites of expression for GLUT1

Answer 330

Substrates are glucose, galactose, mannose, and glucosamine
Major sites of expression are erythrocytes, CNS, blood-brain barrier, placenta, fetal tissues in general

Question 331

Name the substrates and major sites of expression for GLUT2

Answer 331

Substrates are glucose, galactose, fructose, mannose, glucosamine
Major sites of expression are liver, beta-cells of pancreas, kidney, small intestine

Question 332

Name the substrates and major sites of expression for GLUT3

Answer 332

Substrates are glucose, galactose, mannose, xylose, dehydroascorbic acid
Major sites of expression are brain (neurons), spermatozoa, placenta, preimplantation embryos

Question 333

Name the substrates and major sites of expression for insulin dependent GLUT4

Answer 333

Substrates are glucose, glucosamine, dehydroascorbic acid
Major sites of expression are muscle, heart, brown and white adipocytes

Question 334

Name the substrates and major sites of expression for GLUT5

Answer 334

Substrates are fructose, but not glucose
Major sites of expression are intestine, kidney, brain, skeletal muscle, adipose tissue

Question 335

The net chemical reaction of glucose catabolism results in:

Answer 335

An equal number of moles of CO2 and oxygen, creating a respiratory quotient of 1

Question 336

Glycosis converts glucose into:

Answer 336

Pyruvate

Question 337

Where does the glycolytic pathway in the cell take place?

Answer 337

Cytoplasm

Question 338

Approximately __ kcals are released per mole of ATP

Answer 338

7

Question 339

What are the 3 major enzymes in glycolysis?

Answer 339

Glucokinase, phosphofructokinase, and pyruvate kinase

Question 340

Where in the cell does the TCA cycle occur?

Answer 340

Mitochondria, only under aerobic conditions

Question 341

What is the metabolic reaction of cell respiration?

Answer 341

The TCA cycle

Question 342

Using the pyruvate-lactate pathway, how many ATPs can be generated per molecule of pyruvate?

Answer 342

2

Question 343

The oxidation of 1 glucose molecule produces __ molecules of ATP total from which 2 types of reactions?

Answer 343

36 molecules of ATP. 4 molecules via substrate phosphorylation (2 from glycolysis and 2 from pyruvate decarboxylation) and 32 molecules via oxidative phosphorylation

Question 344

Which pathway allows some organisms to survive under anaerobic conditions?

Answer 344

Pyruvate-lactate pathway

Question 345

What are the 4 distinctive, irreversible reactions of gluconeogensis?

Answer 345

1. Pyruvate is carboxylated in mitochondria to oxaloacetate
2. The formed oxaloacetate is phosphorylated in the cytosol to phosphoenolpyruvate
3. Special phosphatases hydrolyze fructose 1,6-biphosphate
4. Special phosphatases hydrolyze glucose 6-phosphate

Question 346

When can amino acids and fat provide carbon for gluconeogenesis?

Answer 346

During fasting or carbohydrate deprivation

Question 347

What is the purpose of gluconeogenesis?

Answer 347

It is the endogenous formation of glucose and is important to maintain plasma glucose concentration in the normal range during fasting and allows constant provision of energy for metabolic needs

Question 348

The body stores carbohydrate as:

Answer 348

Glycogen

Question 349

In a 70 kg healthy person, the liver contains approximately __ gm of glycogen

Answer 349

100 gm (has the potential to provide 390 kcal)

Question 350

Skeletal muscle contains about ___ gm of glycogen which suggests that an adult has enough glycogen to last for how long while performing normal activities?

Answer 350

Contains 300-400 gm glycogen, yielding less than 1560 kcal, suggesting that an adult stores enough glycogen for about a day of normal activities

Question 351

The formation of glycogen is called ___, and the breakdown of glycogen is called ___

Answer 351

Glycogenesis
Glycogenolysis

Question 352

Glycogen synthesis and glycogenolysis are regulated by the rate-limiting enzymes:

Answer 352

Glycogen synthase and glycogen phosphorylase, respectively

Question 353

What are the primary substrates to gluconeogensis?

Answer 353

Lactate, glutamine, alanine, and glycerol

Question 354

After 14 days of fasting, adipose tissue can provide more than what percent of daily energy requirements?

Answer 354

90%

Question 355

After how many weeks of starvation is the brain able to adapt to using ketones as a source of energy?

Answer 355

1-2 weeks

Question 356

Describe how stress hyperglycemia occurs?

Answer 356

During periods of trauma and illness, there is increased production of stress hormones such as epinephrine and cortisol, accompanied by an elevation in growth hormone and glucagon. These counterregulatory hormones oppose insulin action, causing increased glucose production by the liver (may exceed 500 gm glucose per day) and decreased utilization of glucose in peripheral tissues. Acute and chronic disease and injury can also increase production of cytokines which further contribute to hyperglycemia through stimulation of counterregulatory hormone release and suppression of insulin action

Question 357

How can gastric emptying be delayed in regard to fiber intake?

Answer 357

Increased viscosity of gastric contents, which reduces pyloric flow

Question 358

A minimum of __ gm of carbohydrates per day is required to avoid ketone production

Answer 358

50 gm

Question 359

During moderate exercise, approximately __% of energy is provided by glucose

Answer 359

60%

Question 360

What should be done if a pregnant patient with gestational diabetes loses weight?

Answer 360

If patient’s response to diagnosis of gestational diabetes is to self-starvation to avoid hyperglycemia, test urine for ketones and increase carb intake

Question 361

Describe direct calorimetry and how it is performed

Answer 361

Measures heat and chemical energy released from the body. Heat is considered a direct measurement of metabolic rate because the fuel energy used by the body is ultimately transformed to heat. Urine also is collected to account for the small amount of chemical energy lost in urea excretion in urine. These machines consist of a living space or chamber thermally isolated from the outside, with equipment to extract and measure the heat released into the air of the chamber from the subject residing within. Most appropriate in the study of healthy subjects in research/academic environments due to the individual needing to remain alone in the chamber without caregivers or medical equipment. Can last for days.

Question 362

Describe indirect calorimetry and how it is performed

Answer 362

Gas exchange and heat measurements are obtained simultaneously and are used to deduce the ratios of gas exchange to head production and prove the equivalence pf the 2 processes. The measurement of gas exchange is shown to be an indirect but accurate reflection of energy expenditure. Subjects do not need to be isolated as long as respiratory gases can be completely captured for approximately 30 minutes. Most IC devices consist of sensors for measuring oxygen and CO2 concentrations in inspired and expired air, a device for measuring exhaled minute volume, and a computer system to calculate parameters and manage data.

Question 363

What is the Reverse Fick Equation?

Answer 363

An estimation of oxygen consumption, derived from oxygen content differences in arterial and mixed venous blood multiplied by cardiac output measurements from pulmonary artery catheters. Not useful for clinical assessment of energy expenditure

Question 364

What is the Doubly Labeled Water technique?

Answer 364

A method for assessing energy expenditure that involves administering a stable isotope of water (2H2O) to the patient and measuring its disappearance rate over time (days). The disappearance of 2H is proportional to water turnover, whereas the disappearance of 18O is proportional to water turnover plus VCO2 production. The difference between the 2 disappearance rates is the VCO2. VO2 is computed from the food quotient (FQ - the sum of the CO2 produced from all food eaten divided by the sum of the oxygen consumed during oxidation of all food eaten). Useful for research, not used in clinical care.

Question 365

Name the relative indications for Indirect Calorimetry

Answer 365

BMI <20.5
BMI >80
Concern about overfeeding in a patient with unexplained high ventilator requirement or who for an unknown reason cannot be liberated from the ventilator
Unwanted weight loss over time not explained by volume status in a patient who regularly receives nearly 100% of target feeding
Massive tissue loss from amputation
Preadmission fluid overload (ascites, volume resuscitation, “third spacing”) without a reliable report of body weight at proper hydration

Question 366

What are the contraindications for Indirect Calorimetry?

Answer 366

Air leak (chest tubes, cuff leak, any other leak in ventilator circuit, leaks around face masks, canopies, etc.)
ECMO
HD (during and for several hours afterwards)
For mechanically vented patients, a fraction of inspired oxygen >60%
For spontaneously breathing patients:
- Reliance on any supplemental oxygen (cannula, face mask, etc.)
- Inability to cooperate with the measurement
- Claustrophobia or any anxiety about the measurement

Question 367

What is the amount of time that IC measurements are useful for in critically ill, mechanically ventilated patients?

Answer 367

3-4 days

Question 368

What is the maximum BMI that was used when the Mifflin - St. Jeor equation was being studied?

Answer 368

Maximum BMI of 42

Question 369

How is the accuracy rate of the Mifflin-St. Jeor equation affected when applied to obese people?

Answer 369

It falls somewhat. Accuracy of 75% in people with BMI 30 or higher, compared to 87% in people with BMI less than 30

Question 370

What are the 2 earliest and most common ways to predict RMR in critically ill patients?

Answer 370

Using a ratio of kcal to kg of body weight OR calculate healthy RMR (with Harris-Benedict or Mifflin-St. Jeor) and multiply by a stress factor.

Question 371

In which populations has the Penn State Equation been demonstrated to be accurate?

Answer 371

Morbidly obese (80% accuracy up to a BMI of at least 80)
Brain injuries (72% accuracy)
Barbiturate coma (73% accuracy)

Question 372

In which populations does the Penn State Equation lose accuracy?

Answer 372

Low BMI (63% accuracy when BMI is <20.5)
Cystic fibrosis (58% accuracy; many of these patients had very low BMI which might be the underlying reason for the low accuracy rate)

Question 373

VCO2 stands for:

Answer 373

Volume of CO2 production

Question 374

VCO2 is calculated as:

Answer 374

The breath-by-breath exhaled volume multiplied by the fraction of expired CO2, averaged over a minute, and then aggregated to a 24-hour period

Question 375

VO2 stands for:

Answer 375

Oxygen consumption

Question 376

VO2 calculation:

Answer 376

VO2 = VCO2/RQ
VO2 is calculated from the algebraic manipulation of the RQ (respiratory quotient) equation and combined with the Weir equation to calculate RMR

Question 377

What is the equation for RMR measurement (kcal/day) using ventilator-derived measurement of CO2 production?

Answer 377

VO2 = VCO2/RQ
where RQ is calculated from the actual fuel intake, or assumed to be approximately 0.85
RMR = (VO2 x 3.91) + (VCO2 x 1.1) + 144
where RMR is measured in kcal/day, and VO2 and VCO2 are measured in mL/min

Question 378

Show the modified Weir equation (used with VO2 and VCO2 to interpret IC data)

Answer 378

RMR = [(VO2 x 3.94) + (VCO2 x 1.1)] x 1.44

Question 379

What is the metabolic range of RQ?

Answer 379

0.67 to 1.3

Question 380

Show the Mifflin-St. Jeor equation

Answer 380

Men: RMR = 5 + (10 x W) + (6.25 x H) - (5 x A)
Women: RMR = -161 + (10 x W) + (6.25 x H) - (5 x A)
where RMR is measured in kcal/day, W is weight in kg, H is height in cm, and A is age in years

Question 381

Show the Penn State equation

Answer 381

RMR = (Mifflin-St. Jeor x 0.96) + (Ve x 32) + (Tmax x 167) - 6212
where RMR and MSJ are measured in kcal/day, Tmax is the maximum body temp in the previous 24 hours (celsius) and Ve is minute ventilation in L/min

Question 382

What are the 3 major components of total energy expenditure (TEE)?

Answer 382

1. Basal metabolic rate (BMR) or resting metabolic rate (RMR)
2. Energy required for thermogenic effect of digestion
3. Energy expenditure associated with physical activity

Question 383

What is the difference between BMR and RMR?

Answer 383

BMR is metabolic rate measured in a fasting state, immediately upon awakening and before any physical activity is undertaken. RMR is also measured in a fasted state, but some movement is allowed before testing (dressing, walking)

Question 384

What are the influences on RMR?

Answer 384

Determined by body size and composition, sex, and age. Some sex and age effects are indirect, being the result of the amount or composition of the fat-free mass rather than related to biological sex differences or age.

Question 385

Name the numerous factors that seem to influence the thermogenic effect of digestion

Answer 385

Diet factors (size and composition of the meal, time of day the meal is eaten), age, smoking, stress, caffeine use.

Question 386

True or false: The thermogenic effect of digestion is induced in healthy people who are being fed with a continuous infusion of liquid formula via gastric feeding tube.

Answer 386

False. It is NOT induced.

Question 387

How does tissue synthesis in nutrition repletion, pregnancy, and childhood increase energy requirements?

Answer 387

Tissue synthesis is a high-energy activity. The newly synthesized tissue is composed of fuel (protein and fat), and the synthesis of new tissue from individual amino acids, fatty acids, and glucose is an energy-requiring reaction.

Question 388

A study found that differences in RMR of trauma, surgical, and medical critical care patients were eliminated when which factor was controlled?

Answer 388

Temperature.

Question 389

The length of time before bodily function compromise occurs after energy needs are not being met depends on:

Answer 389

The patient’s nutrition status, the size of the energy deficit, the body compartment being catabolized

Question 390

In what conditions will a critical deficit in energy be reached sooner?

Answer 390

Malnourished patients (they start with a reduced tissue reserve), hypermetabolic patients (they create larger daily deficits), and in cases where inflammatory response favors catabolism of protein over fat

Question 391

Which particular fatty acids are critically important to proper development as well as inflammatory and other physiological processes?

Answer 391

Arachidonic acid, eicosapentaenoic acid (EPA), and docohexaenoic acid (DHA)

Question 392

What are the basic contents of triglyceride structure?

Answer 392

A glycerol backbone and various fatty acids attached in ester linkage at the carbon-1 (sn-1), carbon-2 (sn-2), and carbon-3 (sn-3) positions

Question 393

Why does a gram of fat stored in tissue have more recoverable energy than a gram of carbohydrate?

Answer 393

TGs have a lower intrinsic level of oxidation than carb, and the weight contribution of water common to carbs and proteins is missing from lipids

Question 394

Which fatty acids necessary for life can humans not synthesize and why?

Answer 394

Linoleic acid and alpha-linolenic acid. The specific desaturase enzymes that can introduce a doube bond past position 9-10 within a given fatty acid are absent, which prevents the de novo synthesis of linoleic and alpha-linoleic acids.

Question 395

Linoleic acid and alpha-linolenic acid serve as precursors for the synthesis of which other necessary long-chain unsaturated fatty acids?

Answer 395

Arachidonic acid (AA) and docohexaenoic acid (DHA)

Question 396

What is the intestinal activity that is critical for metabolism of long-chain TGs?

Answer 396

The emulsification process and micelle formation that makes TGs and fatty acid esters available for hydrolysis by intestinal lipases and esterases

Question 397

What types of fats can be directly absorbed in the villi of the intestinal mucosa?

Answer 397

Ingested glycerol and individual fatty acids. MCT (medium-chain triglycerides) lipid emulsions can be directly absorbed without requiring either bile salts for emulsification or energy for uptake

Question 398

What are ILEs (lipid injectable emulsion), and what concentrations are available in commercial ILEs?

Answer 398

Oil-in-water emulsions consisting of 1 or more TG-containing oils, glycerin, and a phospholipid emulsifier, available in concentration of 10%, 20%, and 30% (w/v).

Question 399

How can hypertriglyceridemia occur with the provision of lipids in PN?

Answer 399

It occurs when the body cannot clear TGs from plasma lipids via oxidation and/or storage in adipose tissue, and it may be caused when the supply of lipids into the bloodstream exceeds lipoprotein lipase activity or when lipoprotein activity is reduced

Question 400

What is the most common pathway of oxidative degradation of fatty acids?

Answer 400

Beta-oxidation

Question 401

What is the suggested % of total energy as linoleic acid and alpha-linolenic acid that should be provided to prevent essential fatty acid deficiency (EFAD)?

Answer 401

1-4% for linoleic acid
0.25-0.5% for alpha-linolenic acid

Question 402

The two 100% soybean oil-based emulsions available for IV use in the US provide what percent of total energy from linoleic and alpha-linolenic acid?

Answer 402

55-60% of energy from linoleic acid and 3-4% total energy from alpha-linolenic acid

Question 403

What is the most common lipid regimen in adult PN patients with 100% soybean oil-based ILEs that is prescribed to meet EFA requirements?

Answer 403

500 ml of a 20% ILE may be given weekly

Question 404

ASPEN guideline when using soybean oil emulsion as the sole IV fat sourse?

Answer 404

The ILE should be held for the first week or given at a maximum of 100 g/week if there is concern or risk for EFAD

Question 405

In adult patients requiring PN, ILEs should not exceed ___ g lipid per kg per day

Answer 405

2.5 g

Question 406

It is recommended that the infusion rate for ILEs does not exceed ___ gm/kg/hour, for what reason?

Answer 406

Recommended to limit the infusion rate so it does not exceed 0.11 gm/kg/hour to prevent potential adverse reactions or toxicities associated with rapid infusion

Question 407

What strategies can prevent adverse metabolic outcomes when propofol is used concomitantly with nutrition support?

Answer 407

Clinicians should monitor serum TG concentration frequently (twice per week).
To lower the total fat dose and possibly improve TF clearance, lipids should be removed from PN solutions.
Recommendations for acceptable TG levels are <250 mg/dL 4 hours after ILE infusion for “piggy backed” lipids and <400 mg/dL for continuous ILE infusion.
Patient could be started on a hypocaloric, fat-free PN (=/< 20 kcal/kg/day) (if failed trophic EN).

Question 408

What are the biochemical and clinical manifestations of EFAD (that were observed in patients requiring PN for extended periods of time [2-4 weeks])?

Answer 408

Clinical symptoms: increased susceptibility to infection, impaired wound healing, and immune dysfunction
Biochemical changes in response to linoleic acid deficiency are manifested by a decrease in linoleic acid and AA levels and an increase in the mead acid level (mead acid primarily produced in humans in the absence of EFAs)
Triene:tetraene ratio > 0.2

Question 409

Why might EFAD occur rapidly in patients receiving fat-free PN administration?

Answer 409

Due to elevated insulin levels that prevent adipose tissue lipolysis.

Question 410

Why might the period of time be extended before a patient exhibits EFAD when receiving hypocaloric fat-free PN or a cyclic feeding schedule of fat-free PN?

Answer 410

It is thought that when PN is cycled or hypocaloric PN Is provided, essential fatty acids are mobilized and enter the circulation as a result of increased lipolysis of endogenous fat stores in response to a reduction in serum insulin concentration. In addition, hypocaloric feeding prevents the risk of hepatic dysfunction that may occur if the energy deficit (caused by the removal of lipids) is corrected by increasing the energy from dextrose or protein to maintain energy requirements

Question 411

How can essential fatty acid deficiency (EFAD) be prevented when a lipid-free PN regimen is initiated in the ICU?

Answer 411

Patients should be monitored for EFAD if all sources of lipids are removed from the diet for more than 2-4 weeks. The dosing of ILEs depends on energy expenditure, the patient’s clinical status, body weight, tolerance, and ability to metabolize lipids. Providing 2-4% of energy requirement as linoleic acid may correct EFA insufficiency. Should calculate the linoleic acid dose from 100% soybean ILE or an alternative ILE to ensure adequate dosing of EFAs. Initiation of low dose or trophic EN may also be used to offset risk of EFAD. A polymeric enteral formula containing soybean oil and a mixture of other high-linoleic oils may be used. Generally, a polymeric enteral formula that provides 10-15% of patient’s total energy requirements will supply adequate EFAs. However, when the patient is at high risk for fat malabsorption, or when enteral feeding is interrupted or stopped for a significant period (14 days) with no other lipid source provided, the linoleic acid dose and EFAD risk should be evaluated

Question 412

What is the ASPEN recommendation regarding the use of immune modulating formulations in critical illness?

Answer 412

Immune-modulating enteral formulations of arginine with other agents - including EPA, DHA, glutamine, and nucleic acid - should not be used routinely in medical ICU. These formulas and similar ones (eg, fish oil with or without arginine) should not be administered to severely septic patients

Question 413

Under which conditions does ASPEN recommend formulations that contain fish oil and arginine be considered?

Answer 413

Severe trauma and TBI

Question 414

What is the primary source of SCFAs?

Answer 414

The large intestine via bacterial anaerobic fermentation of nondigestible dietary carbohydrates and fiber polysaccharides.

Question 415

Fermentation of nondigestible carbohydrates and fiber polysaccharides produces which SCFAs?

Answer 415

Acetate, propionate, butyrate

Question 416

Name some of the functions of SCFAs

Answer 416

A primary energy source for colonocytes, stimulation of water and sodium absorption in the colon, and trophic effects to the intestinal mucosa.

Question 417

Which SCFA has been shown to be the most important in regulation and maintenance of colonic tissue and why?

Answer 417

Butyrate. An important role may be to modify inflammatory activity by inhibiting the release of the transcription factor, nuclear factor lambda-light-chain-enhancer, of activated B cells. Exhibits antitumorigenic effects on cancer cell lines and has been identified with gene regulation involving processes of cellular apoptosis, proliferation, and differentiation

Question 418

Describe some differences between long-chain triglycerides and medium-chain triglycerides

Answer 418

MCTs are smaller and more water soluble, liberation of fatty acids through hydrolysis of MCTs in the intestinal lumen is significantly faster relative to LCTs, absorption of MCFAs is more rapid. MCTs do not require the presence of bile or pancreatic lipases for absorption and are transported directly to the liver via the portal vein. MCTs not stored to any significant degree in adipose tissue, nor do they affect reticuloendothelial system. MCTs are ketogenic, and may provide a useful energy source for enterocytes, lymphocytes, and cells of other tissues in hypermetabolically stressed patients. Oxygenation of MCTs is less affected by glucose and insulin than LCTs. Oxidation of LCTs can be impaired by slow elimination rates from the plasma or by the requirement of carnitine for intracellular transport; metabolism of MCTs is a carnitine-independent system for transport into the mitochondria.

Question 419

What is the energy density of MCTs?

Answer 419

8.3 kcal/g

Question 420

What are structured lipids?

Answer 420

“Designer” TG molecules that are specifically synthesized in the lab via chemical and/or enzymatic methodology or via genetic engineering. These TG mixtures contain a randomly esterified pattern of MCTs and LCTs that can contain within the same TG molecule both MCFAs and LCFAs

Question 421

What are some benefits of a structured lipid?

Answer 421

Offer a defined mechanism to rapidly deliver MCFAs and to provide a more rapid availability of EPA and DHA with the entire attendant array of nutritionally positive aspects of these substances. Benefits also include better fatty acid absorption, lower infection rates, improved hepatic, renal, and immune function.

Question 422

How do fatty acids in the omega-6 family influence the immune system?

Answer 422

Alteration of membrane structure and function, by modulation of immune function through AA metabolites, and by stimulation of inflammatory cytokines

Question 423

What is Smoflipid?

Answer 423

A newer generation alternative ILE that is composed of a blend of soybean oil, olive oil, fish oil, and MCTs. Available in US. Contains approximately 67% less linoleic acid than soybean oil.

Question 424

What is ClinOleic/Clinolipid?

Answer 424

A blended, alternative ILE composed of soybean and olive oil. Not commercially available in US. Contains approximately 66.2% less linoleic acid than soybean oil.

Question 425

Why have commercial ILEs with high olive oil content been developed?

Answer 425

To reduce omega-6 fatty acid and thus the risk associated with in vivo oxidative stress and the potential for a proinflammatory environment

Question 426

Describe various differences in olive-oil ILE compared to soybean oil ILE

Answer 426

Olive oil-based ILEs are less inhibitory of various neutrophil responses, including human neutrophil viability, phagocytic activity, inflammatory cytokine production, and oxidative burst induction. Greater immune-neutral effect

Question 427

What are the benefits of MCT-LCT emulsions (50:50 w/w mixture) in PN solutions?

Answer 427

Providing a better oxidized energy source, improving nitrogen balance (attenuating protein catabolism in stress), and providing rapid clearance of lipid from the blood. Patients getting these emulsions have been shown to have a fatty acid profile that is closer to normal when compared with individuals who receive soybean-based ILEs

Question 428

Which of the following showed improved nitrogen balance, more protection of the liver, more efficiently eliminated TGs, and a strong trend toward a shorter hospital LOS? Structured lipid, MCT-LCT PN emulsion (structured lipid group), or a physically mixed MCT-LCT PN emulsion (MCT/LCT group)?

Answer 428

Structured lipid group

Question 429

What are the most common phytosterols and what are they?

Answer 429

Campesterol, sitosterol, and stigmasterol. They are plant analogues of cholesterol and are found in all currently available plant-based ILE formulations. May interfere with bile acid homeostasis

Question 430

What is the hypothesis that data is consistent with regarding phytosterols in plant-based ILE formulations?

Answer 430

High phytosterol exposure is associated with PNALD and, reduction of soybean-based ILE and/or use of fish oil that does not contain any phytosterols can reduced the incidence of PNALD

Question 431

What are the nutritionally essential amino acids?

Answer 431

Phenylalanine, isoleucine, leucine, lysine, methionine, threonine, tyrptophan, valine, and histidine

Question 432

Describe the main functions of proteins and amino acids

Answer 432

1. Growth, maintenance, and movement: proteins form integral parts of most body structures (skin, tendons, membranes, muscles, organs, bones). Support growth and repair of body tissues
2. Enzymes: facilitate chemical reactions
3. Hormones: some are made of proteins, functioning as messengers and signals and regular body processes
4. Immunity: antibodies, cytokines, and chemokines are proteins; regulate gene transcription and translation through mTOR signaling pathway
5. Fluid and electrolyte balance: help maintain fluid volume and the composition of body fluids
6. Acid-base balance: act as buffers
7. Transportation and storage: transport substances (lipids, vitamins, minerals, and oxygen); some store a specific micronutrient

Question 433

What are the 4 levels of protein structure?

Answer 433

Primary structure, secondary structure, tertiary structure, quaternary structure

Question 434

Name some examples of transport proteins

Answer 434

Hemoglobin (carries oxygen from lungs to the cells)
Lipoprotein (transports lipids around the body)
Retinol-binding protein (transports retinol from liver to target tissues)
Albumin
Prealbumin

Question 435

What are the secretory sites, main target sites, and functions of Gastrin?

Answer 435

Secreted in pyloric antrum, duodenum, and pancreas
Target site is parietal cell
Acid secretion, gastric contraction

Question 436

What are the secretory sites, main target sites, and functions of Secretin?

Answer 436

Secreted in duodenum
Main target site is pancreas
Water and bicarbonate secretion

Question 437

What are the secretory sites, main target sites, and functions of Cholecystokinin?

Answer 437

Secreted in duodenum and jejunum
Main target sites are pancreas and gallbladder
Pancreatic enzyme secretion, gall bladder contraction

Question 438

What are the secretory sites, main target sites, and functions of Gastric inhibitory peptide?

Answer 438

Secreted in duodenum and jejunum
Main target site is pancreas
Insulin secretion

Question 439

What are the secretory sites, main target sites, and functions of Glucagon-like peptide-1?

Answer 439

Secreted in small intestine (L cell)
Main target site is pancreas
Insulin secretion

Question 440

What are the secretory sites, main target sites, and functions of Glucagon-like peptide-2?

Answer 440

Secreted in small intestine (L cell)
Main target site is small intestine
Intestinal growth (crypt cell)

Question 441

What are the secretory sites, main target sites, and functions of Peptide YY?

Answer 441

Secreted in small intestine (L cell)
Main target site is brain stem
Slowing the gastric emptying, reducing appetite

Question 442

What are the secretory sites, main target sites, and functions of Somatostatin?

Answer 442

Secreted in pyloric antrum, hypothalamus
Main target sites are GI tract, pituitary gland
Suppressing the release of GI hormones

Question 443

What are endogenous sources from which protein enters the GI tract?

Answer 443

Desquamated mucosal cells, digestive enzymes, other glycoproteins such as mucus

Question 444

Which amino acids are the most rapidly absorbed?

Answer 444

Methionine, leucine, isoleucine, and valine

Question 445

What percent of dietary protein is absorbed as dipeptides and tripeptides? What percent is absorbed as free amino acids?

Answer 445

67% and 33%

Question 446

What are the limitations of of free amino acid formulas in the clinical setting?

Answer 446

Higher osmolality, less palatable, cost more. Elemental formulas vs polymeric did not show and advantage with the former for patients with Crohn’s disease

Question 447

What factors affect the accuracy of nitrogen balance measurement?

Answer 447

Renal dysfunction, errors in estimating intake, or incomplete collection of urine, stool, fistula, or ostomy losses may affect balance results

Question 448

What is the formula for calculating nitrogen balance (NB)?

Answer 448

NB = Nitrogen Intake - Nitrogen Output

Question 449

What is the formula for calculating Nitrogen Output (g/day)?

Answer 449

Nitrogen Output (g/day) = [Urinary Urea Nitrogen (mg/100 ml) x Urinary Volume (L/d)/100] + 20% of Urinary Urea Losses + 2 gm

Question 450

What are the best ways to evaluate protein adequacy after traumatic injury?

Answer 450

Nitrogen Balance; made easier when the sole nutrition source is PN or EN. Clinical guidelines help define protein requirements in critical illness, but it is often necessary to adjust protein goals depending on the clinical condition of the patient (eg, worsening renal function where protein may need to be decreased).

Question 451

Describe the characteristics of arteriovenous amino acid differences across organs as a measure of protein metabolism

Answer 451

Invasive method
A tracer amino acid should be infused
Samples of blood are obtained from both the arterial and venous catheter
The measurements are made across muscle beds

Question 452

Describe the characteristics of tracer methodology as a measurement of protein metabolism

Answer 452

Constant infusion method used in human studies
No requirement for a steady state
Ideal for measuring acute changes in patients
Important research tool

Question 453

Describe the characteristics of urinary creatinine excreted over 24 hours as a measurement of protein metabolism

Answer 453

Indirect measurement of muscle mass
Has high variation

Question 454

Describe the characteristics of urinary 3-methyl histidine excretion as a measurement of protein metabolism

Answer 454

Can be used as a measure of muscle degradation
Compromised accuracy with organ dysfunction

Question 455

What functions are amino acids used for within the intestinal cell?

Answer 455

Synthesis of nucleic acids, glutathione, apoproteins as components of lipoproteins, or other nitrogen-containing compounds
Secretory protein synthesis
Act as an important energy source to the GI tract

Question 456

Name the gluconeogenic amino acids

Answer 456

Alanine, glycine, cysteine, serine, threonine, asparagine, arginine, aspartic acid, histidine, glutamic acid, glutamine, isoleucine, methionine, proline, valine, and phenylalanine

Question 457

In critically ill patients, hepatic glucose production ___ which can contribute to what condition?

Answer 457

Increases; hyperglycemia

Question 458

What is the key role of alanine and glutamine in muscle BCAA metabolism?

Answer 458

They participate in the process to remove nitrogen wastes that are produced during BCAA oxidation

Question 459

Which amino acid is the only one that undergoes a complete oxidation pathway in muscle (via the formation of acetyl coA)?

Answer 459

Leucine

Question 460

Describe the role of the liver in regards to protein

Answer 460

Regulates the flow of dietary amino acids and other nitrogenous compounds derived from tissue degradation
Synthesizes plasma proteins
Metabolism of toxic nitrogenous wastes that have accumulated from exogenous protein intake or from protein breakdown during catabolic states (sepsis, trauma)
Carbon skeletons from gluconeogenic acids can be metabolized to glucose
Site of gluconeogenesis

Question 461

Describe the role of the kidneys in regards to protein

Answer 461

Involved in interorgan exchange and synthesis of a variety of amino acids
Major site for arginine, histidine, and serine production
Conversion of phenylalanine to tyrosine and glycine to serine
Site of gluconeogenesis
Remove nitrogenous waste from the body (urea)

Question 462

What is the hepatic metabolite of ammonia?

Answer 462

Urea

Question 463

Describe the role of the brain and central nervous system in regards to protein

Answer 463

Amino acids are required for neurotransmitter synthesis (tyrosine used to synthesize catecholamines)
Inhibitory neurotransmitters (glycine and taurine)
Glutamine helps rid the brain of ammonia
Neuropeptides act as potent neurotransmitters (mediate sensory and emotional responses

Question 464

Protein is the primary substrate for which metabolic process during starvation metabolism?

Answer 464

Gluconeogenesis

Question 465

How soon does glycogenolysis (breakdown of hepatic glycogen stores) occur after fasting? How long until stores are depleted?

Answer 465

2-3 hours; 24 hours

Question 466

Which organs are the site of gluconeogenesis and begins how soon after a meal?

Answer 466

Occurs in liver and kidneys, starts within 4-6 hours after last meal

Question 467

After 2 days of starvation, what does the brain switch its fuel source to?

Answer 467

Switches from glucose to ketone bodies

Question 468

What is the PDCAAS?

Answer 468

Protein digestibility-corrected amino acid score
represents the relative adequacy of a protein’s most limiting amino acid

Question 469

What is the PDCAAS equation?

Answer 469

PDCAAS (%) = [mg of limiting amino acid in 1 g of test protein)/(mg of same amino acid in 1 g of reference protein)] x fecal true digestibility percentage

Question 470

What would a PDCAAS of 100% mean?

Answer 470

That 100% of the amino acids of a protein after digestion can be used for protein synthesis, or that the protein contains all essential amino acids in adequate proportions

Question 471

The nitrogen content of proteins varies from __% to __%, and nitrogen conversion factors range from __ to __

Answer 471

13-19%
5.26-7.69

Question 472

How is the protein content for enteral and parenteral formulations determined?

Answer 472

Amino acid analysis; the protein content can be calculated from its amino acid concentrations

Question 473

The total amount of protein provided from an IV amino acid mixture is about __% less than what would be assumed. Why?

Answer 473

17%
When a peptide bond is made, a molecule of water is released; thus, the weight of a peptide bond is 18 mass units less than its molecular weight

Question 474

Example: to provide 1.0-1.5 gm of protein per kg of body weight via PN, how many gm of a mixed amino acid solution needs to be administered?

Answer 474

1.2-1.8 gm

Question 475

Formula for converting nitrogen to protein

Answer 475

Protein = Nitrogen x 6.25

Question 476

Why is there negative nitrogen balance after minor elective surgery?

Answer 476

Due to a decrease in protein synthesis

Question 477

Why would there be a negative nitrogen balance with severe sepsis and injury?

Answer 477

Both protein synthesis and catabolism are elevated and feeding further increases turnover

Question 478

What are the risks of feeding too much protein in critical illness?

Answer 478

Prerenal azotemia (with excess protein increasing the burden to the kidneys to work to excrete excess urea nitrogen). Excess protein feeding over long term can result in kidney stones and increased risk for osteoporosis

Question 479

Why might metabolic rate and protein requirements for an underweight individual be higher per kg of body weight?

Answer 479

The more metabolically active central protein compartments (liver, heart, lungs, brain) make up a greater proportion of the total body weight; and there is a loss of both fat and muscle

Question 480

What is the most abundant amino acid in the body?

Answer 480

Glutamine - accounts for more than 50% of the intracellular free amino acid pool in the muscle

Question 481

Which amino acids serve as the body’s primary nitrogen shuttle between muscle and visceral organs?

Answer 481

Glutamine and alanine

Question 482

Choline can be manufactured in the liver from ___

Answer 482

Methionine

Question 483

Examples of conditionally essential amino acids under certain clinical conditions

Answer 483

Tyrosine, cysteine, glutamine, histidine, taurine

Question 484

Amino acids with pharmacological potential

Answer 484

Arginine, carnitine, choline, creatine, beta-hydroxy methylbutyrate (HMB - a metabolite of leucine)

Question 485

populations at risk for vitamin D deficiency

Answer 485

fat malabsorption, pancreatic insufficiency, decreased bile acid secretion, decreased intestinal surface area

Question 486

the first part of the body to show micronutrient deficiencies

Answer 486

oral cavity

Question 487

the first sign/symptom to detect a micronutrient deficiency

Answer 487

serum labs

Question 488

B12 and Copper deficiency are identical, the distinguishing factor is

Answer 488

B12 is macrocytic and Copper is hypochromic

Question 489

Non-B complex vitamins (water soluble)

Answer 489

B vitamins, ascorbic acid, choline

Question 490

micronutrients absorbed primarily in the stomach

Answer 490

Intrinsic factor, alcohol, copper, molybednum

Question 491

micronutrients primarily absorbed in the duodenum

Answer 491

iron, selenium, calcium, phosphorous, magnesium, copper, thiamine, riboflavin, niacin, folate, A,D,E,K

Question 492

micronutrients primarily absorbed in the jejunum

Answer 492

pantothenate, vitamin B6, zinc, chromium, manganese, , thiamine, riboflavin, vitamin C, iron, magnesium, ADEK, calcium, phosphorous

Question 493

micronutrients are primarily absorbed in the ileum

Answer 493

B12, bile salts/acids, magnesium, vitamin C, D and K

Question 494

micronutrients absorbed in the large intestine

Answer 494

vitamin K and biotin

Question 495

major micronutrients deficient in roux-en-y gastric bypass

Answer 495

iron, calcium, intrinsic factor, b12, copper, fluoride, vitamin D, bile salts and thiamine

Question 496

most likely micronutrient deficiency with an ileal resection <100cm of terminal ileum left over

Answer 496

B12, sodium, bile salts/acids limiting fat absorption, limited fat soluble vitamins

Question 497

micronutrient losses associated with loss of terminal ileum

Answer 497

B12, Bile salts, fat malabsorption, fat soluble vitamin malabsorption, decreased essential fatty acid absorption, gastric hypersecretion and SIBO B12 deficiency

Question 498

if the colon is intact, bacteria can produce _____ ,____,____, and ___in the setting of a lost ileum

Answer 498

thiamine, riboflavin, pantothenic acid, vitamin K

Question 499

is there any evidence to support vitamin A supplementation in wounds

Answer 499

No

Question 500

deficiency of vitamin ___ can delay wound healing as scar tissue wouldn’t be able to form from collagen

Answer 500

vitamin C

Question 501

role of vitamin E for wound healing

Answer 501

an antioxidant used in collagen synthesis

Question 502

is vitamin E beneficial in wound healing

Answer 502

YES

Question 503

Name the fat-soluble and water-soluble vitamins

Answer 503

Fat-soluble: vitamins A, D, E, and K
Water-soluble: all B vitamins, C, and choline

Question 504

3 forms of Vitamin A?

Answer 504

Retinol, retinaldehyde (retinal), and retinoic acid

Question 505

Typical form that vitamin A is ingested as?

Answer 505

Retinyl ester

Question 506

Primary storage sites of vitamin A

Answer 506

Liver is primary site. Also stored in adipose tissue, kidneys, bone marrow, lungs, eyes

Question 507

Role of vitamin A in wound healing?

Answer 507

As retinoic acid, it is needed for epithelial cell growth. Vitamin A increases the number of macrophages and monocytes in the wound during the inflammatory phase, stimulates epithelialization, increases collagen deposition by fibroblasts. Can also reverse the inhibitory effects of corticosteroids on wound healing

Question 508

1 mcg of retinol is equivalent to the activity of __ mcg beta-carotene from food?

Answer 508

1 mcg retinol = 12 mcg beta-carotene

Question 509

RAE (retinoic acid equivalent) is equal to what amount of each of the following: retinol, IU retinol, mcg food-based beta-carotene, mcg alpha-carotene, mcg beta-cryptoxanthin

Answer 509

1 mcg retinol
3.33 IU retinol
12 mcg food-based beta-carotene
24 mcg alpha-carotene
24 mcg beta-cryptoxanthin

Question 510

How does vitamin D absorption occur?

Answer 510

In tandem with fat and bile salts via passive diffusion into the intestinal cell where it is packaged as chylomicrons for entrance into the lymphatic system and then into the blood

Question 511

What is the first B vitamin deficiency that usually manifests in alcoholism?

Answer 511

Thiamine

Question 512

What considerations should be made when a patient on warfarin therapy is receiving PN?
Scenario: 52 y/o M w/ stage IV colon cancer s/p chemo presents w/ severe nausea, vomiting, abd pain, and distention, last BM 5 days ago with no intake other than sips of fluids. Pt is found on CT to have an ileus and also DVT of LLE. NG placed to suction. Unable to tolerate oral feedings after 48 hours of admission so PN is started. Advanced to liquid diet and transitioned to warfarin therapy with a target INR of 2-3. During warfarin therapy INR remains subtherapeutic despite frequent increases in warfarin dose until it reaches abnormally high levels

Answer 512

Nutrition support clinician should assess the vitamin K intake from PN sources and its impact on warfarin dosage. PN is adjusted to decrease vitamin K to achieve therapeutic INR at a stable warfarin dose. If possible, switch patient to a multivitamin product that does not contain vitamin K, such as MVI-12 (Hospira). If lipid emulsion also provides a high dose of vitamin K, it may also be adjusted

Question 513

Vitamin K content of parenteral multivitamin Infuvite? Range of vitamin K content in lipid emulsions depending on the fat source?

Answer 513

150 mcg vitamin K per unit dose (10 mL)
0-1000 mcg vitamin K per liter in lipid emulsions

Question 514

What is an extra challenge with the provision of nutrition support to patients receiving warfarin therapy?

Answer 514

The variable vitamin K content in lipid emulsions along with the periodic nature of their administration (lipids given 3 times/week rather than daily)

Question 515

Describe the vitamin K content of Propofol?

Answer 515

Propofol is 10% soybean oil. Soybean oil has approximately 1.7 mcg vitamin K per mL

Question 516

How does thiamin deficiency affect nutrient metabolism?

Answer 516

Thiamin is necessary for the conversion of pyruvate to acetyl-CoA, a major step in the transformation of glucose to adenosine triphosphate. In the absence of thiamin, energy metabolism is impaired. As pyruvate builds up, it is driven toward lactic acid fermentation, which causes the spike in lactate and contributes to metabolic acidosis. Thiamin is necessary for the Krebs cycle enzyme alpha-ketoglutarate dehydrogenase. Together, these conditions decrease the acetyl-CoA entering the Krebs cycle from carb metabolism and limit the energy substrates produced in the Krebs cycle from fatty acid-derived acetyl-CoA

Question 517

Patient scenario: Patient presents with SOB, restlessness, mild confusion. Also with severe edema in lower extremities and abdominal ascites 2/2 alcoholic liver cirrhosis. Oral intake has been inadequate for the past month due to binge drinking. Started on furosemide 40 mg. Day 2 restlessness progresses to combative behavior, increased confusion, nystagmus, leg tremor. ABG indicative of metabolic acidosis which is unresponsive to treatment. Serum Mg is 1.5, slightly below normal. What is the appropriate intervention?

Answer 517

Wernicke encephalopathy 2/2 thiamin deficiency is suspected. Furosemide is discontinued and replaced with oral spironolactone. Furosemide promotes urinary thiamin wasting. A multivitamin is administered along with thiamin (200mg 3x daily) for 5 days. Initial dose is given with- 1gm Mg sulfate. Confusion and agitation, as well as metabolic lactic acidosis, resolve within 6 hours of treatment. Patient sent home on oral thiamin supplement of 100mg 3x/day. Dose decreased to 100mg/day in 2 weeks

Question 518

Describe the mechanisms through which severe alcoholism causes thiamin deficiency

Answer 518

1. People with alcoholism often replace nutrient-dense energy sources with energy from alcohol intake, which can lead to malnutrition
2. Ethanol inhibits intestinal thiamin absorption
3. The active for of thiamin, thiamin pyrophosphate, is synthesized in the liver, making liver cirrhosis a possible contributing factor in thiamin deficiency

Question 519

Thiamin deficit occurs within how many days of inadequate intake?

Answer 519

14-20 days

Question 520

What nutrient is necessary for the conversion of thiamin to its active form, thiamin diphosphate?

Answer 520

Magnesium. A Mg deficiency effectively renders thiamin unusable

Question 521

What is the suggested thiamin replacement for suspected Wernicke encephalopathy or Wernicke-Korsakoff syndrome (from a recent compilation of evidence, however recommendations vary widely)?

Answer 521

For 3-5 days: 100-200 mg IV or intramuscular thiamin 3x/day before high carb meals
For the next 1-2 weeks: 100 mg oral thiamin 3x/day
Then 100 mg oral thiamin once daily thereafter

Question 522

What is the recommended treatment for confirmed Wernicke encephalopathy or Wernicke-Korsakoff syndrome?

Answer 522

200-500 mg IV or intramuscular thiamin 3x/day for 5-7 days
100 mg oral thiamin 3x/day for the next 1-2 weeks
Then 100 mg oral thiamin once daily thereafter

Question 523

Which essential amino acid can synthesize the coenzyme nicotinamide adenine dinucleotide (NAD)?

Answer 523

Tryptophan. 60 mg tryptophan produces 1 mg niacin

Question 524

Nutrients of concern when a tuberculosis patient is being treated with Isoniazid?

Answer 524

Niacin (B3), Vitamin B6 (pyridoxine)

Question 525

Besides inadequate iron intake, what other mineral deficiencies or excesses may create hematological indices consistent with iron deficiency anemia and why?

Answer 525

Copper deficiency interferes with iron absorption and thus effectively creates copper deficiency anemia (iron deficiency anemia in patients with iron replete status). Zinc toxicity creates a copper deficiency, initiating the same mechanisms. Chromium toxicity can contribute to iron deficiency anemia due to its receptor site competition with iron

Question 526

Which cells in the GI tract secrete more than 30 GI hormone peptides?

Answer 526

Neuroendocrine cells

Question 527

What are the major inputs influencing appetite regulation?

Answer 527

Short term signals related to meal ingestion that are transmitted by the “gut-brain” axis
Signals associated with energy stores that are mediated by leptin
Signals deriving from lean body mass
Circadian rhythm

Question 528

What is the major orexigenic (appetite stimulating) gut hormone?

Answer 528

Ghrelin

Question 529

Name anorexigenic (appetite suppressing) gut hormones

Answer 529

Glucagon-like peptide-1 and -2 (GLP-1, GLP-2)
Oxyntomodulin (OXM)
Peptide tyrosine-tyrosine (PYY)
Pancreatic polypeptide (PP)
Cholecystokinin (CCK)

Question 530

How are gut- and fat-derived hormones (ghrelin, leptin, insulin, and PYY) involved in feedback regulation of feeding?

Answer 530

Through signals affecting hunger, satiety, and energy needs

Question 531

How does ghrelin increase food intake?

Answer 531

By stimulating the ARC of the hypothalamus

Question 532

Where in the brain are neural and hormonal signals that influence food intake located?

Answer 532

The arcuate nucleus (ARC) of the hypothalamus and the brainstem

Question 533

Name the site of secretion, stimulating factors, mechanism of action, and effect of GLP-1 (glucagon-like peptide-1)

Answer 533

Distal gut
Stimulated by food intake proportional to energy intake
Works by binding GLP-1 receptors in pancreatic islet cells, heart, lungs, and brain (ARC and PVC)
Reduces appetite and energy intake; delays gastric emptying; enhances postprandial insulin release

Question 534

Name the site of secretion, stimulating factors, mechanism of action, and effect of OXM (oxyntomodulin)

Answer 534

L cells of the distal gut
Stimulated by food intake
Works as agonist at glucagon receptor; has undefined neural effects
Reduces food intake; increases energy expenditure

Question 535

Name the site of secretion, stimulating factors, mechanism of action, and effect of PYY (peptide-tyrosine-tyrosine)

Answer 535

L cells of the distal gut
Stimulated by food intake (released in proportion to energy, fat, and protein intake)
Mechanism of action: Y receptors found throughout the CNS and on vagal afferents, NPY (neuropeptide Y) inhibition, POMC (proopiomelanocortin) activation, associated with increased activity of OFC (orbitofrontal cortex)
Reduces food intake

Question 536

Name the site of secretion, stimulating factors, mechanism of action, and effect of PP (pancreatic polypeptide)

Answer 536

Pancreatic polypeptide cells of the islets of Langerhans in the pancreas
Stimulated by food intake and vagal stimulation
Enters CNS via diffusion in the brain stem and ARC
Reduces food intake

Question 537

Name the site of secretion, stimulating factors, mechanism of action, and effect of CCK (cholecystokinin)

Answer 537

L cells of the gut, nerves in distal ileum and colon, neurons in the brain
Stimulated by dietary protein and fat, gastric acid
Reduces hypothalamic NPY (neuropeptide Y)
Inhibits gastric emptying and reduces food intake

Question 538

Name the site of secretion, stimulating factors, mechanism of action, and effect of Leptin

Answer 538

Large amounts from the gastric mucosa; white adipose tissue
Food deprivation is associated with low levels
Low levels influence ARC; possibly decreases gene expression of NPY and increases activity of POMC-secreting neurons
Low levels increase energy intake and decrease energy expenditure

Question 539

Name the site of secretion, stimulating factors, mechanism of action, and effect of Ghrelin

Answer 539

Stomach
Food intake decreases levels; fasting increases levels
Stimulates ARC via receptors; stimulated GH secretion
Increases food intake

Question 540

Describe the role of fiber (especially resistant starch R2) on the feeding response

Answer 540

It has satiety value with associated decreases in food intake

Question 541

True or false: stomach size can influence the amount of food eaten

Answer 541

True. Its size is related to the amount of food habitually eaten.

Question 542

How is aging associated with decreased appetite and food intake

Answer 542

Likely because of decreased basal hunger rather than increased meal satiety

Question 543

Name some adverse effects that have been associated with megestrol

Answer 543

Nausea, vomiting, gas, diarrhea

Question 544

GI muscle fibers are depolarized (contraction of the muscle) in response to?

Answer 544

Stretching of the muscle fiber
Acetylcholine released by parasympathetic neurons
Gut hormones

Question 545

Inhibition of GI muscle contraction is associated with a hyperpolarized state which is caused by?

Answer 545

Norepinephrine or epinephrine
Sympathetic nerves that secrete norepinephrine

Question 546

How is the enteric nervous system connected to the central nervous system?

Answer 546

By parasympathetic fibers (stimulates motility) and sympathetic fibers (modulates activity of ENS with inhibitory signals)

Question 547

Factors that regulate gastric emptying

Answer 547

Volume of food
Gastrin
Enteric gastric nervous reflexes from the duodenum
Ghrelin
Hormonal feedback from the duodenum

Question 548

What are the neurotransmitters of the ENS?

Answer 548

Acetylcholine
Norepinephrine and serotonin
y-aminobutyrate
Adenosine triphosphate (ATP)
Nitric oxide (NO) and carbon monoxide (CO)
Dopamine
CCK
Substance P
Vasoactive intestinal peptide (VIP)
Somatostatin
Leu-enkephalin
Met-enkaphalin

Question 549

What are some sensory stimuli in the ENS that are involved in the neural control of the gut?

Answer 549

Irritation of the mucosa, excessive distention, or chemical stimuli

Question 550

Describe the stimuli for secretion, site of secretion and action of gastrin for GI motility

Answer 550

Stimuli are protein, GI distention, gastric-releasing peptide
Secreted by G cells of the antrum, duodenum, and jejunum
Stimulates gastric acid secretion and mucosal growth; promotes gastric emptying

Question 551

Describe the stimuli for secretion, site of secretion, and action of cholecystokinin for GI motility

Answer 551

Stimuli are protein, fat, and acid
Secreted by I cells of the duodenum, jejunum, and ileum
Stimulates pancreatic enzyme secretion, gallbladder contraction, and growth of exocrine pancreas; inhibits gastric emptying

Question 552

Describe the stimuli for secretion, site of secretion, and action of secretin for GI motility

Answer 552

Stimulus is acid
Secreted by S cells of the duodenum, jejunum, and ileum
Stimulates pepsin, pancreatic and biliary bicarbonate secretion, and growth of exocrine pancreas; inhibits gastric emptying and gastric acid secretion

Question 553

Describe the stimuli for secretion, site of secretion, and action of gastric inhibitory peptide (GIP) for GI motility

Answer 553

Stimuli are protein, fat, carbohydrate
Secreted by K cells of the duodenum and jejunum
Stimulates insulin release and secretion; inhibits gastric acid secretion and emptying

Question 554

Describe the stimuli for secretion, site of secretion, and action of motilin for GI motility

Answer 554

Stimuli are fat, acid, gastric distention, bile acids, serotonin, and low pH in duodenum
Secreted by M cells of the duodenum and jejunum, stomach, colon
Stimulates gastric motility and intestinal motility

Question 555

Describe the stimuli for secretion, site of secretion, and action of vasoactive intestinal peptide (VIP) for GI motility

Answer 555

Stimulus is GI distention
Secreted by nerves of the GI tract
Stimulates secretion of electrolytes and water secretion; inhibits gastric acid

Question 556

Describe the stimuli for secretion, site of secretion, and action of somatostatin for GI motility

Answer 556

Stimulus is acid
Secreted by pancreas, GI mucosa, hypothalamus
Inhibits secretion of gastrin, VIP, GIP, secretin, motilin, exocrine pancreatic secretion, gallbladder contraction, gastric acid secretion, and gastric motility

Question 557

Describe the stimuli for secretion, site of secretion, and action of serotonin (5-HT) for GI motility

Answer 557

Stimuli are luminal contents including glucose and SCFAs, GI distention
Secreted by nerve fibers of the enteric nervous system
Increases intestinal motility

Question 558

Describe the stimuli for secretion, site of secretion, and action of peptide-tyrosine-tyrosine (PYY) for GI motility

Answer 558

Stimulus is fat
Secreted by jejunum
Inhibits gastric acid secretion and gastric motility

Question 559

What motor functions of the stomach contribute to digestion?

Answer 559

Storing food, mixing food with gastric secretions, and emptying the semifluid mixture (chyme) into the duodenum

Question 560

What factors decrease gastric tone?

Answer 560

Duodenal distention, colonic distention, ileal perfusion with glucose

Question 561

The inhibitory reflexes of the duodenum are stimulated by what 5 factors?

Answer 561

1. duodenal distention
2. irritation of the duodenal mucosa
3. pH less than 3.5 or 4.0
4. high osmolality
5. the presence of breakdown products of protein and fat digestion

Question 562

Which macronutrient is the strongest stimulus for hormones of the duodenum and jejunum?

Answer 562

Dietary fat

Question 563

The tone of which portions of the stomach influence liquid and solid emptying?

Answer 563

Proximal stomach influences liquid emptying
Distal stomach is involved in solid emptying

Question 564

What is the average half-emptying time of water or isotonic saline?

Answer 564

12 minutes
Example: if one drinks 300 ml of water, 150 ml will enter the duodenum in about 12 minutes

Question 565

What factors regulate liquid emptying?

Answer 565

Duodenal osmoreceptors, secretin, and VIP

Question 566

What is the half-emptying time of solids?

Answer 566

45-110 minutes

Question 567

Intragastric pressure ____ in response to the swallowing reflex and in response to gastric distention by the presence of food

Answer 567

Falls

Question 568

What is the volume that a relaxed stomach can hold?

Answer 568

0.8 to 1.5 L

Question 569

What factors influence the rate of gastric emptying time of solids?

Answer 569

Meal particle size, energy content, and fat content

Question 570

When the swallowing mechanism is bypassed, such as in NG feeding, the rate of gastric emptying is ______.

Answer 570

Faster

Question 571

Why would gastric emptying time decrease if feeding tubes are placed in the jejunum, bypassing the duodenum?

Answer 571

The duodenal mucosa possesses sensory receptors that are associated with neurohormonal reflexes that influence gastric emptying time

Question 572

What factors determine the amount of chyme that enters the intestine from the stomach?

Answer 572

Duodenal distention, acidity, osmolar changes, and the presence of products of carbohydrate, protein, and fat digestion

Question 573

When are segmentation contractions (mixing contractions) of the small intestine elicited?

Answer 573

When the small intestine is distended by chyme

Question 574

What is the average time it takes for chyme to travel from the pylorus to the ileocecal valve?

Answer 574

3-5 hours. The rate of mixing contractions is 2-3 per minute or maximally 12 per minute. Propulsive movements of the small intestine (peristalsis) move in the direction of the anus at a rate of 0.5-2.0 cm/second.

Question 575

When is neural control partly initiated during intestinal peristalsis?

Answer 575

When chyme stretches the intestinal wall

Question 576

What are the stimulatory hormones of intestinal peristalsis?

Answer 576

Gastrin, CCK, insulin, motilin, and serotonin

Question 577

What is the volume of chyme that empties into the cecum?

Answer 577

1500-2000 ml/day

Question 578

What is the purpose of the ileocecal valve?

Answer 578

To prevent backflow of fecal content into the small intestine

Question 579

How long does it take for chyme to move from the ileocecal valve through the colon?

Answer 579

8-15 hours

Question 580

On average, after abdominal surgery, the small intestine regains peristalsis within ____ hours (or sooner), and motility of the stomach and colon returns between ____ and ____ hours

Answer 580

24, 48, 72

Question 581

In a previously well-nourished patient, parenteral nutrition should only be considered after how many days of NPO?

Answer 581

7 days. PN has been associated with higher infection morbidity in previously well-nourished patients compared with standard care

Question 582

Aside from abdominal surgery, what other conditions/situations can cause ileus?

Answer 582

Infection, inflammation, electrolyte imbalance, the use of certain drugs such as sedatives, opioid analgesics, a2-adrenergic receptor agonists, catecholamine vasopressors

Question 583

Name potential etiologies or contributing factors of ileus?

Answer 583

Opiate use, sympathetic hyperactivity, altered spinal-intestinal neural reflexes, changes in hormone expression and secretion, hypomagnesemia, hypokalemia, and local and systemic inflammation

Question 584

What is chronic intestinal pseudo-obstruction (CIP)?

Answer 584

A motility disorder of peristalsis that most often affects the small bowel but can occur at any point in the GI tract

Question 585

Name the secondary causes of CIP

Answer 585

Collagen vascular and endocrine diseases, neurological diseases, medication-related effects

Question 586

Describe the treatment plan for CIP

Answer 586

Palliation of symptoms including nausea and vomiting with antiemetics and/or prokinetics, provision of IV hydration or PN, nocturnal cyclic EN when possible, and, when necessary, withholding of oral intake of food

Question 587

What is the preferred mode of nutrition for CIP?

Answer 587

Oral

Question 588

Describe the MNT for CIP patients who can consume an oral diet

Answer 588

Recommend small, frequent meals low in fat and fiber, with an emphasis on liquid forms of energy and protein. Daily multivitamin and mineral supplement is recommended, and if the patient has small intestinal bacterial overgrowth (SIBO), emphasis should be placed on fat-soluble and B12 vitamins.

Question 589

List serious consequences of diarrhea

Answer 589

Severe fluid and electrolyte abnormalities; fluid loss, dehydration, hypovolemia; hypovolemic shock and cardiovascular collapse; increased risk of pressure ulcers, compromised nutrition status, increase hospital LOS

Question 590

What percent of cases of antibiotic-associated diarrhea (AAD) is from C. difficile infection?

Answer 590

20%

Question 591

What is the standard recipe for oral rehydration solution published by the World Health Organization?

Answer 591

2.6 gm NaCl, 13.5 gm anhydrous glucose, 1.5 gm potassium chloride, 2.9 gm trisodium citrate, and 1 L water

Question 592

What MNT should be offered to a patient who has reobstruction of the small intestine after surgery (lysis of adhesions) for small bowel obstruction?

Answer 592

If the patient has a normal nutrition status on admission, the best nutrition intervention is no initial intervention. Would keep patient NPO on bowel rest and evaluate for PN on hospital day 7

Question 593

What enteral MNT would you offer to a patient with severe diarrhea related to C.diff pseudomembranous colitis (PMC)?

Answer 593

Evidence-based diet recommendations for PMC diarrhea have not been established, however the goal is to initiate nutrition through the GI tract as early as possible to limit gut mucosa atrophy. Would keep patient NPO until diarrhea improves of antibiotic therapy, then initiate on caffeine-free clear liquids, and then advance to low-lactose, low-fat, low-fiber diet. Supplemental fiber use in C.diff diarrhea is not supported by ASPEN. IV fluids if oral intake does not keep up with losses. PN should not be offered unless patient presents severely malnourished.

Question 594

How do SCFAs help control diarrhea?

Answer 594

By stimulating the uptake of water and electrolytes by colonocytes

Question 595

Name some causes of gastroparesis

Answer 595

Diabetes mellitus (at least 25% of cases), complications of surgery, renal disease, collagen disease, drugs, malignancy, hypothyroidism, and possible idiopathic reasons

Question 596

What surgical intervention can be offered for a patient who fails medical treatment for gastroparesis?

Answer 596

A near-total gastrectomy and Roux-en-Y gastrojejunostomy.

Question 597

What are the dietary treatments for gastroparesis?

Answer 597

Small, frequent meals, drinking fluids with meals, limiting dietary fat and fiber, maintaining good glucose control, and, when necessary, feeding past the pylorus

Question 598

What nutrition intervention is recommended for a patient with gastroparesis who has failed to respond to dietary intervention?

Answer 598

Jejunostomy-tube placement for long-term intestinal feedings and oral diet of small amounts of low-fat, low-fiber foods with liquids as tolerated (to address the psychosocial need to eat). If patient is receiving nighttime cyclic feedings, may also need to change to a longer-acting insulin to control glucose levels during nighttime feeding. Jejunal feedings bypass the stomach and obviate the potential of formula intolerance associated with delayed gastric emptying.

Question 599

Name conditions associated with constipation

Answer 599

Diabetes mellitus, hypothyroidism, hypercalcemia, dehydration, neurologic disorders, anorectal disease, and collagen vascular/muscular diseases

Question 600

What are the first-line medication treatments for constipation when nonpharmacological approaches fail? Second-line?

Answer 600

First-line: Hydrophilic colloids (psyllium, bran methylcellulose, polycarbophil), stool softeners, osmotic laxatives (polyethylene glycol, lactulose, sorbitol, and magnesium salts).
Second-line: Stimulants (senna/docusate, bisacodyl/docusate, or casanthranol/docusate) and lubricants (mineral oil).

Question 601

What is the disadvantage of using mineral oil for constipation?

Answer 601

It binds fat-soluble vitamins and, if aspiration occurs, could cause a lipoid pneumonia.

Question 602

What is dumping syndrome?

Answer 602

A group of symptoms that develop after gastric surgery and are related to increased gastric emptying following vagotomy and bypass or destruction of the pylorus. Can also occur with too rapid infusion of EN through a small-bore feeding tube. It is accompanied by both GI symptoms and vasomotor symptoms.

Question 603

What are the GI and vasomotor symptoms of dumping syndrome?

Answer 603

GI symptoms: feeling of fullness after eating, crampy abdominal pain, nausea, vomiting, and explosive diarrhea
Vasomotor symptoms: diaphoresis, weakness, dizziness, flushing, and palpitations

Question 604

What are the time frames for early vs late dumping?

Answer 604

Early: within 30-60 minutes of eating
Late: occurs 2-3 hours after eating and is limited to vasomotor symptoms

Question 605

What is the cause of the GI and vasomotor symptoms of dumping syndrome?

Answer 605

GI: related to the rapid emptying of hyperosmolar chyme into the small intestine from the stomach, eliciting an osmotic diuresis into the intestinal lumen and subsequent distention
Vasomotor: rapid delivery of glucose to the upper small intestine, which results in peripheral and splanchnic vasodilation. This rapid delivery precipitates and increased serum insulin release followed by hypoglycemia and vasomotor symptoms

Question 606

What is the dietary treatment for dumping syndrome?

Answer 606

Involves slow introduction of solid food, elimination of simple sugars, frequent small meals, and no liquids with meals. Patients are advised to lie down after eating and consider adding functional fibers to delay gastric emptying. The initial post-op period should not include simple sugars. Dairy products should be restricted initially because temporary lactose intolerance may occur. Liquid multivitamin/mineral supplements and vitamin B12 injections may be warranted in patients who have undergone a gastric resection.

Question 607

What are the 2 primary functions of secretions in the GI tract?

Answer 607

To supply digestive enzymes and to supply lubricating mucus

Question 608

What populations are at risk for xerostomia?

Answer 608

Obese patients, older adults, patient’s with Sjogren’s syndrome, those undergoing radiotherapy or chemotherapy for cancer, those with hormone disorders and infections

Question 609

What are some consequences of hyposalivation?

Answer 609

Alterations in taste perception, chewing and swallowing problems, intolerance of spicy foods, can encourage dietary choices that compromise nutrition status and increase the risk for dental plaque and periodontal disease

Question 610

How does hyposalivation occur with obesity?

Answer 610

Via increased leptin and decreased ghrelin

Question 611

What are the contents of saliva?

Answer 611

Mucin (for lubrication), ptyalin (alpha-amylase; enzyme for starch digestion), immunoglobulin A (IgA), lysozyme (for protection against oral bacteria), components that play a role in innate immunity

Question 612

How much saliva do humans secrete each day?

Answer 612

Approximately 1000-1500 ml/day

Question 613

Where do gastric secretions derive from?

Answer 613

Mucus-secreting cells, oxyntic glands (gastric glands), and pyloric glands

Question 614

What 3 cells make up oxyntic glands?

Answer 614

Mucus-producing cells, peptic (chief) cells, and parietal cells

Question 615

Peptic cells secrete ___ and ___; parietal cells secrete ___ and ___.

Answer 615

Pepsinogen and gastric lipase
Hydrogen chloride (HCl) and intrinsic factor

Question 616

What is the pH of the gastric acid?

Answer 616

Approximately 0.8

Question 617

What is a possible consequence of the destruction of parietal cells, such as with chronic gastritis?

Answer 617

Achlorhydria (the absence of acid) develops in addition to pernicious anemia and vitamin B12 deficiency caused by loss of intrinsic factor. Intrinsic factor is required for the absorption of vitamin B12 and is secreted by the same cells that secrete HCl

Question 618

What are the biochemical stimulants for acid secretion?

Answer 618

Gastrin, histamine via H2 receptors, and acetylcholine released by parasympathetic stimulation

Question 619

Gastrin is secreted in response to the presence of ___

Answer 619

Luminal oligopeptides (peptide products of protein digestion), gastric distention, and GRP (bombesin)

Question 620

The presence of carbohydrate, protein, or fat in the duodenum ____ gastric acid and pepsin secretion as well as gastric motility

Answer 620

Inhibits

Question 621

Caffeine and alcohol ____ gastrin and acid production

Answer 621

Stimulate

Question 622

Peptic ulcers develop when ____ is compromised

Answer 622

The gastric lining’s protective barrier against irritation and autodigestion

Question 623

What is the treatment for peptic ulcers?

Answer 623

Suppression of gastric acid production, ie. Proton-pump inhibitors (exert their effects on acid suppression by interfering with hydrogen potassium ATP activity), H2-receptor antagonist drugs (block histamine stimulation of acid production)

Question 624

What are the 3 phases in which gastric juice is secreted?

Answer 624

1. Cephalic phase
2. Gastric phase
3. Intestinal phase

Question 625

Describe the cephalic phase of gastric juice secretion

Answer 625

Acid is secreted via vagal stimulation in response to the sight, smell, and/or taste of food. Vagus nerve releases acetylcholine (stimulates ECL cells and parietal cells). Accounts for 30% of the volume of acid secretion.

Question 626

Describe the gastric phase of gastric juice secretion

Answer 626

Begins when food arrives in the stomach. Amino acids and peptides stimulate the G cells in the antrum to produce gastrin (enters the general circulation and stimulates parietal cells as an endocrine hormone). Gastric distention also leads to acid secretion via a reflex involving the vagus nerve. Accounts for 60% of the volume of acid secretion.

Question 627

Describe the intestinal phase of gastric juice secretion

Answer 627

Food in the duodenum continues to stimulate small amounts of gastric secretions (likely related to the small amount of gastrin that is secreted by the duodenal mucosa). Accounts for approximately 10% of gastric acid secretion.

Question 628

Describe the multiple ways in which gastric secretions are inhibited by signals from the intestines

Answer 628

Food in the small intestine stimulate gastrin release and initiates a reverse enterogastric reflex that inhibits gastric secretions. The presence of acid, fat, products of protein digestion, hyper- or hypotonic fluids, or irritants in the proximal small bowel stimulate the secretions of gastric secretion-inhibiting hormones (secretin, GIP, VIP, somatostatin). The presence of carb, protein, or fat in the duodenum inhibits gastric acid and pepsin secretion and gastric motility.

Question 629

What are the components of bile?

Answer 629

Water, bile salts, bile pigments, cholesterol, lecithin, fatty acids, and electrolytes

Question 630

What are the two principal bile acids?

Answer 630

Cholic acid and chenodeoxycholic acid

Question 631

What are the secondary bile acids that are converted by colonic bacteria?

Answer 631

Cholic acid converts to deoxycholic acid
Chenodeoxycholic acid converts to lithocholic acid

Question 632

What are the bile pigments?

Answer 632

Bilirubin and biliverdin

Question 633

Describe jaundice and how it can be detected

Answer 633

Jaundice occurs in pathological conditions when bilirubin accumulates in the blood, skin, sclera, and mucous membranes. It imparts a yellow color and can be detected when total plasma bilirubin exceeds 2 mg/dL

Question 634

Bile production is stimulated by ___ and ___

Answer 634

The vagus nerve and secretin

Question 635

What is the sphincter of Oddi?

Answer 635

The exit of the common bile duct into the duodenum. It remains closed between meals, directing bile to the gallbladder. It relaxes (opens) after a meal (especially if it is high in fat) when the gallbladder contracts. Relaxation of the sphincter is mediated by the action of CCK

Question 636

How much bile is secreted per day?

Answer 636

Approximately 500 mL

Question 637

What is enterohepatic circulation?

Answer 637

Reabsorbed bile salts (90-95% of which are reabsorbed in the terminal ileum) and bile pigments are transported to the liver via the portal vein and then are reexcreted in the bile

Question 638

What is the role of bile salts in the digestion of fat?

Answer 638

To act as emulsifiers along with phospholipids and monoglycerides

Question 639

In the fasting state without any EN, gastric secretions can amount to ___ to ___ mL/day, and biliary and pancreatic secretions can be up to ____ to ____ mL/day.

Answer 639

500-1000 mL/day
1000-2000 mL/day

Question 640

When colonic pressure increases, the ileocecal valve ____. When ileal pressure increases or when food exits the stomach, the ileocecal valve ___.

Answer 640

Shuts
Opens

Question 641

Brunner glands secrete ___

Answer 641

Mucus, to protect the duodenum from gastric acid

Question 642

Pancreatic secretions, intestinal secretions, and bile neutralize gastric acid to raise the pH of duodenal contents to ___

Answer 642

6-7

Question 643

Name the pancreatic enzymes found in pancreatic juice

Answer 643

Carbohydrate - pancreatic amylase
Protein - pancreatic proteases (trypsin, chymotripsin, carboxypolypeptidase, proelastase, collagenase)
Fat - pancreatic lipase, cholesterol esterase, phospholipase

Question 644

Why do oral rehydration solutions used to treat Na+ and water losses from diarrhea contain NaCl and glucose?

Answer 644

Na+ facilitates the absorption of glucose, some amino acids, and bile acids

Question 645

What percent of dietary iron is absorbed under conditions of iron deficiency?

Answer 645

3-6%

Question 646

Iron absorption is inhibited by:

Answer 646

Phytates in cereal, phosphates, and oxalates. These compounds for insoluble compounds with iron

Question 647

Does the passage of feces continue during prolonged bowel rest when patients are restricted from consuming food?

Answer 647

Yes, fecal contents include material other than food residue. Feces contains bacteria (comprises 30% of the dry weight of fecal matter), inorganic material, fiber, water, sloughed off undifferentiated stem cells

Question 648

How are medium-chain triglycerides absorbed?

Answer 648

MCTs are water soluble, they do not require the formation of micelles or the action of bile salts. MCTs are hydrolyzed and pass through enterocytes directly into the portal circulation. MCTs may be used as an energy supplement in patients who maldigest or malabsorb fat

Question 649

What percent of cardiac output is delivered to the splanchnic circulation at rest?

Answer 649

25%

Question 650

What percent of total body oxygen is consumed at rest by the splanchnic organs?

Answer 650

30%

Question 651

During feeding, splanchnic blood flow increases __% to __% and oxygen demand in the splanchnic-supplied organs increases up to __%

Answer 651

40% to 60%
30%

Question 652

Where does all blood in the GI tract, including the spleen and pancreas, flow to?

Answer 652

To the liver via the portal vein

Question 653

What is the reticuloendothelial system?

Answer 653

A system of macrophages that clears the blood of bacteria and other particulate matter to prevent systemic infection before blood leaves the liver. In the liver, blood encounters RED cells in the lining of sinusoids (liver blood cells).

Question 654

Name the arteries that supply blood to the small intestine. The stomach?

Answer 654

Superior and inferior mesenteric arteries (branch off the aorta) for the small intestine. Celiac artery for the stomach.

Question 655

When does mucosal atrophy occur?

Answer 655

During starvation, stress, PN, and bowel rest

Question 656

True or false: the bowel mucosa requires luminal nutrients to supply its nutrient needs

Answer 656

True. After 1 week of a protein-deficient diet, the microvilli shorten

Question 657

What is the principal metabolic fuel for intestinal cells?

Answer 657

Glutamine. Its absence may directly contribute to mucosal atrophy that accompanies bowel rest.

Question 658

When should EN be withheld in patients with hypoperfused gut?

Answer 658

When patients are being initiated on catecholamines, when catecholamine doses are increasing, or when patients require a high level of hemodynamic support including high-dose catecholamines (norepinephrine, epinephrine, dopamine) to maintain cellular perfusion.