Fundamentals of Nutrition and Metabolism

Question 1

Which of the following is NOT true regarding the small bowel in adult populations?

1: Measures 400-800 cm in length
2: < 100cm without colon requires TPN
3: < 50cm with colon requires TPN
4: Length correlates with weight

Answer 1

4: Length correlates with weight

The small bowel (SB) is 400-800cm or 12-20 feet in length. Less than 100cm with ileostomy requires long term TPN. 100-200cm with ileostomy requires Oral Rehydration (ORS). Less than 50cm with colon requires long term TPN. Over 50cm with colon rarely requires TPN. The small bowel correlates with height, shorter length seen in women.

Question 2

A 72 year old patient with an end ileostomy is at risk for which deficiency?

1: Vitamin A
2: Vitamin K
3: Vitamin B1
4: Vitamin B12

Answer 2

4: Vitamin B12

Vitamin B12 is dependent on normal GI function. It is released from ingested proteins via the action of HCL and pepsin in the gastric secretions. The majority of Vitamin B12 is reabsorbed via enterohepatic circulation. Pancreatic insufficiency, impaired HCl production such as older patients or patients with Helicobacter pylori infections or those taking histamine-2 antagonists or protein pump inhibitors have reduced absorption. Patients with resection of all or part of the ileum or stomach and patients with chronic malabsorption also have reduced absorption. Vitamin K absorption occurs primarily in the jejunum. Vitamin B1 (thiamin) absorption occurs primarily in the proximal small intestine, especially in the jejunum. Vitamin A is primarily absorbed in the upper small intestine.

Question 3

All of the following are true regarding soluble fiber EXCEPT that soluble fiber

1: results in delayed gastric emptying.
2: promotes feeling of fullness.
3: may improve glucose control.
4: increases absorption in the small intestine.

Answer 3

4: increases absorption in the small intestine.

Soluble, viscous fiber results in gastric distention and thus promotes feeling of fullness. This delays gastric emptying and also prevents absorption of nutrients in the small intestine. Some researchers have studied the effects of soluble fiber on blood glucose control and found improvement in blood sugars with fiber-induced delayed gastric emptying.

Question 4

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

1: Copper
2: Manganese
3: Selenium
4: Iron

Answer 4

1: Copper

Copper accumulation in the liver and other organs can occur in Wilson’s disease, which 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 5

The acute phase response has what effect on serum iron and ferritin levels?

1: Increases serum iron levels and increases serum ferritin levels
2: Increases serum iron levels and decreases serum ferritin levels
3: Decreases serum iron levels and decreases serum ferritin levels
4: Decreases serum iron levels and increases serum ferritin levels

Answer 5

4: Decreases serum iron levels and increases serum ferritin levels

The acute phase response to injury and infection suppresses iron transport. Clinically, serum iron levels are depressed, while serum ferritin levels are increased. 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 potential for free radical production and oxidative damage to cell membranes and DNA.

Question 6

The majority of dietary folate is reabsorbed via which of the following mechanisms?

1: Oncotic pressure
2: Enterohepatic circulation
3: Plasma hydrostatic pressure
4: Passive diffusion

Answer 6

2: 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. Zinc deficiency, chronic alcohol consumption, changes in jejunal luminal pH and impaired bile secretion may limit folate absorption. Oncotic pressure, passive diffusion, and plasma hydrostatic pressure govern the movement of fluid between the plasma and interstitial spaces.

Question 7

Choline supplementation has been investigated as a treatment for which of the following disease states?

1: Myocardial infarction
2: Pancreatic insufficiency
3: Hepatic steatosis
4: Alcoholic encephalopathy

Answer 7

3: Hepatic steatosis

Choline is required for lipid transport and metabolism. 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. Further studies to evaluate choline supplementation to prevent and treat PN associated liver disease are needed.

Question 8

Which can decrease the accuracy of an indirect calorimetry (IC) study?

1: Mechanical ventilation with FiO2 is ≥ 60%
2: Holding routine nursing care or activities during the study
3: Measurement made in a quiet, thermoneutral environment
4: Stable nutrient intake for the previous 12 hours

Answer 8

1: Mechanical ventilation with FiO2 is ≥ 60%

IC is the calculation of energy expenditure by analysis of the gas exchanged via measurement of oxygen consumption and carbon dioxide production. The Haldane transformation implies that the inert gas nitrogen (N2) is constant in both inspired and expired gases. If FiO2 is ≥ 60%, the risk of error on the denominator increases. Accuracy of IC measurement is dependent of patient, environmental and equipment related factors. The fraction of inspired oxygen (FiO2) needs to remain constant during the measurement. Measurements should be made in a quiet, thermoneutral environment and routine care during the study should be avoided. The rate and composition of nutrients being infused on a continuous basis should be stable for at least 12 hours for an accurate study.

Question 9

Indirect calorimetry (IC) calculates

1: total energy expenditure.
2: nitrogen balance.
3: heat released from the subject.
4: resting energy expenditure.

Answer 9

4: resting energy expenditure.

IC calculates resting energy expenditure (REE) and respiratory quotient (RQ) by measuring whole body oxygen (V02) and carbon dioxide (VC02) gas exchange using the abbreviated Weir equation. IC does not measure total energy expenditure, nitrogen balance, or heat released from the subject. Total energy expenditure includes resting metabolic rate (RMR), energy required for the thermogenic effect of digestion, and energy expenditure associated with physical activity. Nitrogen balance is determined using urine urea. Heat released from the subject is measured by direct calorimetry, which requires the subject to remain inside of an enclosed chamber during the measurement.

Question 10

Potential metabolic causes for a respiratory quotient (RQ) greater than 1 include all of the following EXCEPT

1: overfeeding.
2: hypoventilation.
3: excess CO2 production.
4: provision of excess sodium bicarbonate.

Answer 10

2: hypoventilation.

Computation of the RQ (ratio of CO2 production to O2 consumption) gives information about the validity of the measurement and the metabolism of the different macronutrients. An RQ of 0.85 indicates mixed substrate utilization, or appropriate nutrient delivery. In general, an RQ < 0.82 suggests underfeeding, or lipid catabolism, indicating the need to increase caloric delivery. An RQ greater than 1.0, with excessive CO2 production may be due to overfeeding, lipogenesis, and increased respiratory demand. A decrease in the total caloric and carbohydrate delivery is an appropriate action when the RQ is greater than 1.0. Administration of excess buffering agents such as sodium bicarbonate can also elevate the RQ. Hypoventilation would tend to reduce RQ measurements.

Question 11

Which of the following are examples of monosaccharides?

1: Galactose, sucrose, and glucose
2: Maltose, fructose, and lactose
3: Glucose, fructose, and galactose
4: Lactose, maltose, and sucrose

Answer 11

3: Glucose, fructose, and galactose

Carbohydrates can be classified as either simple or complex. Simple carbohydrates include monosaccharides (one sugar unit) and disaccharides (two sugar units). Glucose, fructose, and galactose are examples of monosaccharides. The monosaccharides are water soluble and have low molecular weight.

Question 12

Phosphofructokinase, a rate-limiting enzyme of glycolysis, is inhibited when ATP is abundant. Why is this inhibition important?

1: Facilitates gluconeogenesis to maintain euglycemia
2: Allows the cell to divert glucose to be stored as glycogen
3: Promotes catabolism
4: Enhances the Tricarboxylic Acid (TCA) Cycle

Answer 12

2: Allows the cell to divert glucose to be stored as glycogen

Phosphofructokinase, a rate-limiting enzyme of glycolysis, is inhibited when ATP is plentiful. This step is necessary to prevent further breakdown of glucose and allows the cell to divert glucose to be stored as glycogen for later use. When ATP is limited, phosphofructokinase is activated.

Question 13

In the body, glycogen is predominantly found in the

1: brain and liver.
2: skeletal muscle and kidneys.
3: small intestine and brain.
4: liver and skeletal muscle.

Answer 13

4: liver and skeletal muscle.

Glycogen is the storage form of carbohydrate in the body. In general, only approximately 5% of ingested glucose is polymerized into glycogen, with the majority being oxidized. Glycogen is present in small amounts in most body tissues but is mainly found in the liver and skeletal muscle.

Question 14

In response to illness and trauma, there is an increase in which of the following hormones?

1: Cortisol, epinephrine, growth hormone, and glucagon
2: Insulin, epinephrine, estrogen, and somatostatin
3: Glucagon, gastrin, insulin-like growth factor, and renin
4: Leptin, cortisol, growth hormone, and cholecystokinin

Answer 14

1: Cortisol, epinephrine, growth hormone, and glucagon

During periods of illness and trauma, there is increased production of the stress hormones, such as epinephrine and cortisol, accompanied by an elevation in growth hormone and glucagon. These counterregulatory hormones all work to oppose insulin action, resulting in increased glucose production by the liver (may exceed 500 g of glucose/day) and decreased utilization of glucose in peripheral tissues. These changes are also responsible for increased protein breakdown from muscle and enhanced fatty acid oxidation, viewed as a metabolic adaptation to provide fuels for heightened demands.

Question 15

Which of the following tests does not reflect selenium status?

1: Plasma selenium level
2: Erythrocyte selenium concentration
3: Plasma glutathione peroxidase
4: Serum ceruloplasmin level

Answer 15

4: Serum ceruloplasmin level

Measurement of plasma glutathione peroxidase is reflective of the functional or long-term status of selenium. Values <10.5 U/mL erythrocytes are indicative of a deficiency. Selenium status can also be assessed by determining the selenium level in whole blood, plasma, serum, or erythrocytes. Plasma or serum level is reflective of recent selenium intake and levels greater than 100mcg/L represent adequate selenium status in adult patients. Serum ceruloplasmin levels are useful in assessment in copper status.

Question 16

Which of the following is observed in PN patients with inadequate chromium intake?

1: Weight gain
2: Hypoglycemia
3: Hyperglycemia
4: Rhabdomyolysis

Answer 16

3: Hyperglycemia

Chromium potentiates the action of insulin and is important in glucose, protein and lipid metabolism. Chromium deficiency impairs glucose and amino acid use which may result in hyperglycemia.

Question 17

Which of the following is a common clinical sign or symptom seen in a patient with vitamin D toxicity?

1: Hypocalcemia
2: Metabolic bone disease
3: Soft tissue calcification
4: Tetany

Answer 17

3: Soft tissue calcification

Signs of vitamin D toxicity include confusion, psychosis, tremor, hypercalcemia, and hypercalciuria. Soft tissue calcification may occur with long term toxicity in lungs and cardiovasculature. Hypocalcemia, osteomalacia, tetany, and osteoporosis are seen with vitamin D deficiency.

Question 18

Presence of dietary fat in the distal ileum contributes to

1: increased gastric emptying.
2: slowed intestinal transit.
3: bacterial fermentation.
4: production of short chain fatty acids.

Answer 18

2: slowed intestinal transit.

Presence of fat in the distal ileum produces an inhibitor feedback effect called the “ileal brake”, which slows gastric emptying and intestinal transit. Some types of fiber are fermented by bacteria in the colon into short-chain fatty acids.

Question 19

Treatment for gastric phytobezoars includes all of the following EXCEPT

1: flushing with cola.
2: enzymatic therapy with cellulase.
3: meat tenderizer that contains papain.
4: surgical removal of the bezoar.

Answer 19

3: meat tenderizer that contains papain.

Phytobezoars may consist of indigestible plant material such as fiber, skins and seeds. Cellulase and cola have been effectively used to help break down the bezoar. Treatment with papain should be avoided because it breaks down normal tissue and is associated with peptic ulcer disease, esophagitis and gastritis. In cases that do not respond to treatment, surgery can be performed to remove the bezoar.

Question 20

The best method to administer psyllium soluble fiber via feeding tube is to

1: mix with formula and infuse via a gravity feeding bag.
2: mix with formula and infuse with feeding pump.
3: mix with water and other medications and give by syringe followed by 15 mL water flush.
4: mix with water and give by syringe followed by 15 mL water flush.

Answer 20

4: mix with water and give by syringe followed by 15 mL water flush.

Psyllium has been successfully administered via feeding tubes by diluting 1 tsp with 80 mL water, inject by syringe and follow with 15 mL water flush. There may be an association between the intake of dietary fiber and decreased effectiveness of some medications; therefore, timing of fiber and medication administration should be spaced apart. Manipulation of the feeding bag system is a risk for microbial growth through touch contamination.

Question 21

Which of the following methods to determine energy expenditure incorporates body surface area?

1: Harris-Benedict Equation
2: Ireton-Jones Equation
3: Mifflin-St. Jeor Equation
4: Swinamer Equation

Answer 21

4: Swinamer Equation

The Swinamer Equation uses body surface area in addition to physiological variables to predict resting metabolic rate (RMR). This equation has been found to predict RMR in about 55% of patients. Mifflin-St. Jeor Equation and Harris-Benedict Equation use weight, height, and age; Ireton-Jones Equation uses weight, height, age, sex, as well as trauma, and burn.

Question 22

Underfeeding in critically ill patients is associated with

1: increased infections.
2: respiratory compromise.
3: increased CO2 production.
4: decreased days on this ventilator.

Answer 22

1: increased infections.

Underfeeding in critically ill patients increases length of stay, complications, infections, days on antibiotics and days on the ventilator. Overfeeding has the following negative effects: Hyperglycemia, liver dysfunction, fluid overload, respiratory compromise, increased CO2 production and lipogenesis.

Question 23

Soluble fiber benefits which GI condition/symptom?

1: Gastroparesis in tube fed patients
2: Bezoar formation
3: Opioid induced constipation
4: Diarrhea in tube fed patients

Answer 23

4: Diarrhea in tube fed patients

When soluble fiber is added to a liquid meal, it slows the rate of gastric emptying due to increased viscosity. Avoid insoluble and soluble fiber foods/medicatons with a bezoar formation. Insoluble fiber has stool softening effect results in faster transit time and more frequent bowel movements which provides relief from constipation. Soluble fiber is fermented in the distal intestines & increases intestinal mucosal growth and promotes water and sodium absorption. Some studies have shown that TF formula containing soluble fiber reduces the incidence of diarrhea.

Question 24

The FDA-approved lipid injectable emulsion (ILE), that contains four oils differs from soybean oil-based fat emulsion in that it

1: contains egg yolk phospholipid as an emulsifying agent.
2: may be infused via peripheral or central intravenous line.
3: also contains MCT oil, olive oil and fish oil.
4: provides essential fatty acids (EFAs).

Answer 24

3: also contains MCT oil, olive oil and fish oil.

All clinically available ILEs contain egg yolk phospholipid as an emulsifying agent. In addition, all currently manufactured ILEs may be safely infused via a central or peripheral intravenous line. In addition to being an energy source, four-oil and soybean oil-based fat emulsion provide EFAs to prevent the development of EFAD. The four-oil ILE is a blend of 30% soybean oil, 30% MCT oil, 25% olive oil, and 15% fish oil. Its composition serves to be less pro-inflammatory than traditional ILEs given its higher content of omega-3 fatty acids. The four-oil ILE contains an omega-6:omega-3 fatty acid ratio of 2.5:1.

Question 25

Albumin has a half-life of approximately

1: 3 days.
2: 8 days.
3: 12 days.
4: 20 days.

Answer 25

4: 20 days.

Serum albumin is a visceral (hepatic) protein and has a half-life of 14-20 days. The half-lives of retinol-binding protein, prealbumin, and transferrin are approximately 12 hours, 2-3 days, and 8-10 days, respectively.

Question 26

Which of the following vitamins requires bile salts for emulsification and integration into the micelle for intestinal absorption?

1: A
2: B1
3: Choline
4: C

Answer 26

1: A

Absorption of fat-soluble vitamins (A, D, E, and K) requires bile salts for emulsification and integration into the micelle for absorption into the enterocyte. Water-soluble vitamins do not require incorporation into the micelles for intestinal absorption.

Question 27

A patient awaiting lung transplant has been taking a diuretic to control ascites and peripheral edema. Which of the following acid-base disorders is expected?

1: Metabolic acidosis
2: Metabolic alkalosis
3: Respiratory acidosis
4: Respiratory alkalosis

Answer 27

2: Metabolic alkalosis

In this patient, metabolic alkalosis (saline-responsive) is a consequence of chronic diuretic therapy used to control pulmonary edema. These agents cause a loss of bicarbonate-poor, chloride-rich extracellular fluid leading to contraction of extracellular fluid volume. Since the original bicarbonate mass is now dissolved in a smaller fluid volume, an increase in bicarbonate concentration occurs.

Question 28

Which of the following is an example of a short chain fatty acid?

1: Lauric acid
2: Stearic acid
3: Oleic acid
4: Butyric acid

Answer 28

4: Butyric acid

Fatty acids are molecules with an acidic carboxyl group at one end followed by a long chain of hydrogenated hydrophobic carbon atoms. Each fatty acid is chemically characterized by the number of carbon atoms and double bonds present. The four general classifications of fatty acids with respect to the number of carbon atoms are short chain (2-4 carbons), medium chain (6-12 carbons), long chain (14-18 carbons), and very long chain (20 carbons or more). Butyric acid contains 4 carbon atoms and is classified as a short chain fatty acid. Lauric acid (12 carbon atoms) is a medium chain fatty acid. Stearic acid and oleic acid are long chain fatty acids containing 18 carbon atoms each.

Question 29

The basic structure of a triglyceride consists of

1: a phospholipid backbone with 3 fatty acid molecules attached via ester linkage.
2: a fatty acid backbone with 3 glycerol molecules attached via ester linkage.
3: a cholesterol backbone with 3 fatty acid molecules attached via ester linkage.
4: a glycerol backbone with 3 fatty acid molecules attached via ester linkage.

Answer 29

4: a glycerol backbone with 3 fatty acid molecules attached via ester linkage.

The basic structure of a triglyceride consists of a hydroxylated 3-carbon backbone (glycerol). Attached in an ester linkage at the carbon-1, carbon-2, and carbon-3 positions of the glycerol structure are various fatty acids.

Question 30

Triglycerides that require bile acids to facilitate enzymatic digestion and absorption contain fatty acids that are typically

1: 3 carbons in length.
2: 6 carbons in length.
3: 9 carbons in length.
4: 14 carbons in length.

Answer 30

4: 14 carbons in length.

The overwhelming majority of enteral dietary lipids (approximately 90%) are ingested in the form of triglycerides. Bile acids are detergent-like derivatives of cholesterol produced by the liver, which aid in triglyceride emulsification and the formation of micelles in the small intestine. This emulsification process and micelle formation makes triglycerides and fatty esters available for hydrolysis by intestinal lipases and esterases. Fatty acids of up to 10 carbons in length and glycerol can be absorbed directly via the villi of the intestinal mucosa. However, long-chain triglycerides require bile salts for both enzymatic digestion and formation of micelles.

Question 31

Oxidation of fatty acids for adenosine triphosphate (ATP) production occurs in

1: cells that contain mitochondria.
2: the mitochondria of the adipocyte only.
3: the red blood cells only.
4: the blood stream.

Answer 31

1: cells that contain mitochondria.

Mitochondria are organelles found in most eukaryotes whose primary function is to generate ATP via oxidative phosphorylation, the major source of cellular energy. Fatty acids are broken down by various tissues to produce energy. Fatty acids are transported into the mitochondria membrane and through the beta-oxidation pathway the fatty acid is degraded and released as ATP. Fatty acid (and/or lipid) oxidation releases substantially more energy than does oxidation of carbohydrate. Adipocytes store energy as fat. Red blood cells do not contain mitochondria in their cytoplasm and rely on the metabolic pathway of glycolysis for ATP for energy.

Question 32

Linoleic acid and α-linolenic acid are referred to as essential fatty acids for humans because

1: they are the only fatty acids that can be used for adenosine triphosphate (ATP) production.
2: they cannot be synthesized by humans and must be obtained through diet.
3: they are the only fatty acids absolutely required to sustain life.
4: they require L-carnitine to enter the mitochondria.

Answer 32

2: they cannot be synthesized by humans and must be obtained through diet.

Linoleic and α-linolenic acid are called essential fatty acids because they cannot be synthesized naturally by humans and must be supplied, exogenously via the diet. If they are not supplied, a deficiency known as essential fatty acid deficiency (EFAD) can ensue resulting in metabolic complications. All fatty acids (essential, non-essential, saturated or unsaturated, long or short chain) can be oxidized to produce ATP. Because of their length (>10 carbons), linoleic acid and α-linolenic acid both require L-carnitine to enter the mitochondria.

Question 33

A 50-year-old male weighs 80 kg. Calculate the estimated volume of his intravascular space.

1: 4 L
2: 8 L
3: 12 L
4: 16 L

Answer 33

1: 4 L

Water, the most abundant substance in the body, constitutes approximately 50% to 60% of body weight. Total body water (TBW) is a function not only of weight, age, and gender but also of the relative amount of body fat. Of all body tissues, adipose tissue is the least hydrated. Thus, individuals with more body fat have proportionally less TBW content. TBW is distributed among three main compartments: intracellular (ICF), extracellular (ECF), and transcellular fluid compartments. Approximately two-thirds is contained in the ICF, and the remaining one-third is in the ECF. One-fourth of the ECF is the intravascular space and three-fourths is in the interstitial space. Calculations for this patient are: TBW: (80 x 0.6) = 48 L; Extracellular fluid: (1/3 x 48) = 16 L; Intravascular space: (1/4 x 16) = 4 L.

Question 34

Sorbitol-induced hypokalemia is caused by

1: inadequate dietary intake.
2: increased renal potassium loss.
3: excess potassium loss in the stool.
4: transcellular shift of potassium from the extracellular fluid into cells.

Answer 34

3: excess potassium loss in the stool.

Hypokalemia can be the result of abnormal potassium losses via the urine or stool. Hypokalemia can also develop from a transcellular shift of potassium from the extracellular fluid into cells or inadequate dietary intake. Sorbitol induces hypokalemia by promoting excess potassium loss in the stool.

Question 35

Mild hypercalcemia, defined as a total serum calcium of 10.3-11.9 mg/dL, should initially be treated with

1: furosemide diuresis.
2: hydration.
3: hemodialysis.
4: bisphosphonates.

Answer 35

2: hydration.

Mild hypercalcemia usually responds to hydration and ambulation and requires no further intervention. Severe hypercalcemia (total serum calcium of equal to or greater than 14 mg/dL) is treated initially with saline hydration to correct volume depletion and furosemide after hydration to enhance renal calcium excretion. Hemodialysis may be necessary in life threatening situations or in patients with renal insufficiency. Bisphosphonates can assist with treatment of hypercalcemia of malignancy, but their delayed onset of action decreases the utility of these agents in the acute care setting.

Question 36

Absorption of large polypeptides, oligopeptides and free amino acids takes place in the

1: mouth.
2: small intestine.
3: stomach.
4: large intestine.

Answer 36

2: small intestine.

Minimal protein digestion takes place in the mouth or esophagus. Hydrochloric acid secreted by the parietal cells of the stomach denatures the protein and makes it more susceptible for enzymatic action. It converts the inactive pepsinogen to active pepsin. Pepsin in turn activates other pepsinogen molecules or hydrolyzes specific peptide bonds into end products of large polypeptides, oligopeptides and free amino acids. This mixture known as acid chyme passes into the duodenum where majority of protein digestion takes place.

Question 37

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

1: 50%
2: 60%
3: 70%
4: 80%

Answer 37

4: 80%

Determining nitrogen balance using urinary urea is an approximation based on certain assumptions such as urea accounting for about 80% of total urinary nitrogen losses. Urinary urea nitrogen concentration is affected by stress and increased urinary excretion of non-urea nitrogen. Nitrogen balance determined with total urinary nitrogen is consistently more reliable but is typically not available for routine clinical measurements.

Question 38

Supplemental arginine is considered therapeutic for

1: fuel for rapidly dividing cells.
2: increasing lean body mass.
3: immune function and wound healing.
4: improving hepatic steatosis.

Answer 38

3: immune function and wound healing.

Some amino acids administered in higher amounts may have therapeutic effects. Arginine is a semi-essential amino acid that has demonstrated importance in immune function and wound healing. Few studies have focused on chronic wounds and arginine’s effectiveness to enhance wound healing. Supplementation with arginine in the critically ill septic patient population remains controversial.

Question 39

Transformation of free long-chain fatty acids into acylcarnitines requires

1: choline.
2: arginine.
3: glutamine.
4: carnitine.

Answer 39

4: carnitine.

Carnitine is a trimethyl amino acid similar in structure to choline, which is required as a cofactor for transformation of free long-chain fatty acids into acylcarnitines and transport into the mitochondria. Although a primary deficiency of carnitine is rare, it has been documented in preterm infants and chronic renal failure.

Question 40

In which part of the body are essential amino acids oxidized?

1: Muscle
2: Liver
3: Kidney
4: Small intestine

Answer 40

2: Liver

The liver is a key organ for protein metabolism because of its high capacity for uptake and metabolism of amino acids. About 57% of the amino acids extracted by the liver are either oxidized or used to synthesize plasma proteins.

Question 41

Which of the following is a common effect of enteral fiber on the intestinal tract?

1: Faster transit throughout
2: Increased fecal bacteria concentrations
3: Improvement in constipation
4: Improvement in diarrhea

Answer 41

4: Improvement in diarrhea

The influence of dietary fiber on total or oral–anal transit time seems to depend on the type and source of dietary fiber. Both non-fiber and fructooligosaccharide (FOS) containing enteral formulas can decrease overall concentration of fecal bacteria as compared with a normal diet. Soluble fiber may help control diarrhea due to its ability to increase sodium and water absorption via its fermentation byproducts, the SCFAs. At present there is no clear indication that existing constipation can be effectively resolved by increasing the intake of dietary fiber. Using soluble fiber suggests possible benefits in reducing diarrhea during enteral nutrition support.

Question 42

Which of the following is a possible complication of dietary fiber-containing enteral formulas?

1: Impaired glucose metabolism
2: Bloating and flatulence
3: Increased effectiveness of some medications
4: Fluid retention

Answer 42

2: Bloating and flatulence

introduction of a new or large amount of dietary fiber. There have been a few reports of associations between the intake of dietary fiber and decreased effectiveness of antidepressants and lipid-lowering agents. Complications such as formation of an esophageal or intestinal bezoar can be reduced by adequate fluid provision.

Question 43

Insoluble dietary fiber may help to regulate normal defecation by

1: increasing stool weight and bulk.
2: inhibiting the growth of colonic bacteria.
3: reducing incidence of constipation.
4: removing water from the colon.

Answer 43

1: increasing stool weight and bulk.

Insoluble dietary fiber that is not degraded or fermented in the colon increases stool bulk and weight. Unfermented fiber in the colon creates a gel which holds water. Fermented fiber encourages colonic bacterial growth adding to fecal mass. This results in increased stool water content and softened stool consistency to ease evacuation.

Question 44

Consumption of soluble fiber contributes to

1: lower levels of high density lipoprotein cholesterol.
2: lower levels of total and low density lipoprotein cholesterol.
3: lower risk of developing colon cancer.
4: increase in blood glucose concentrations.

Answer 44

2: lower levels of total and low density lipoprotein cholesterol.

Soluble dietary fiber lowers total cholesterol and LDL cholesterol without changing or lowering HDL cholesterol levels. There is currently no clear evidence to support that soluble fiber lowers the risk of developing colon cancer or reducing recurrence of adenomas. Consumption of soluble fiber may result in small decrease of plasma glucose and hemoglobin A1c.

Question 45

During extended periods of fasting (starvation), the main source of energy is from

1: protein catabolism.
2: gluconeogenesis.
3: glycolysis.
4: fatty acid oxidation.

Answer 45

4: fatty acid oxidation.

During starvation, glucose utilization is substantially reduced in most tissues and organs because of a reduced supply of glucose and decline in circulating insulin concentration. Higher glucagon concentrations promote fatty 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.

Question 46

Glycogen stores can sustain normal activities in a healthy 70 kg man for approximately

1: 1 day.
2: 3 days.
3: 7 days.
4: 14 days.

Answer 46

1: 1 day.

In a healthy 70 kg male, the liver contains approximately 100 grams of glycogen, potentially providing 390 kcal. Skeletal muscle contains about 300-400 grams of glycogen, yielding less than 1560 kcal, suggesting that an adult stores only enough glycogen for about a day of normal activity. Because glycogen is stored with water, this is a somewhat inefficient storage method.

Question 47

Glucose and galactose gain access to enterocytes via

1: glucose-dependent insulinotropic polypeptide (GIP).
2: glucokinase.
3: enterokinase.
4: sodium-glucose transporter 1 (SGLT-1).

Answer 47

4: sodium-glucose transporter 1 (SGLT-1).

Glucose and galactose are transported from the intestinal lumen into the enterocyte via the SGLT-1. The transport process requires energy provided by hydrolysis of ATP and is, therefore, called an active transport system. Two molecules of sodium are cotransported with one molecule of glucose or galactose.

Question 48

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

1: Vitamin C and Vitamin B6
2: Vitamin E and Vitamin D
3: Vitamin B12 and Folic acid
4: B1 and Choline

Answer 48

3: Vitamin B12 and Folic acid

Vitamin B12 requires intrinsic factor for absorption. Intrinsic factor binds to B12 and is taken up by receptors in the distal ileum. Folic acid is absorbed by a carrier-mediated process, primarily in the proximal part of the small intestine.

Question 49

Loss of parietal cells after a gastrectomy may lead to a deficiency of

1: vitamin C.
2: vitamin B12.
3: vitamin E.
4: choline.

Answer 49

2: vitamin B12.

Vitamin B12 requires intrinsic factor for absorption. Intrinsic factor, a glycoprotein is secreted by the parietal cells of the stomach, which binds to cyanocobalamin (Vitamin B12) and is taken up by receptors in the distal ileum. Loss of parietal cells for any reason (gastrectomy, pernicious anemia, and chronic gastritis) or loss of distal ileum may lead to Vitamin B12 deficiency.

Question 50

The presence of which of the following facilitates the absorption of sodium in the lumen of the small intestine?

1: Glucose
2: Potassium
3: Vitamin D
4: Protein

Answer 50

1: Glucose

The presence of glucose facilitates sodium absorption. Glucose is co-transported with sodium in the small intestine enhancing both sodium and water uptake. Oral rehydration fluids used to treat diarrhea should contain both NaCl and glucose.

Question 51

Medium-chain triglycerides (MCTs) do not require the formation of micelles or bile salts for absorption because they are

1: fat-soluble.
2: 2-5 carbons in length.
3: water-soluble.
4: anti-inflammatory.

Answer 51

3: water-soluble.

MCTs are hydrolyzed and pass through the enterocytes directly into the portal circulation.

Question 52

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

1: short chain fatty acids.
2: glutamine.
3: glucose.
4: L-cysteine.

Answer 52

2: glutamine.

Mucosal atrophy occurs during periods of bowel rest, minimal PO intake, and stress. Glutamine is a principal metabolic fuel for intestinal cells. An absence of glutamine may directly contribute to mucosal atrophy. Atrophic changes during bowel rest have been decreased with glutamine-enriched parenteral nutrition.

Question 53

An enzyme deficiency commonly seen in African Americans and Native Americans is

1: lactase.
2: maltase.
3: amylase.
4: sucrase.

Answer 53

1: lactase.

70%-100% of African Americans, Native Americans, Asian, and Mediterranean descendents are deficient of lactase enzyme. Low lactose diets or supplemental oral lactase improves dietary tolerance.

Question 54

Symptoms of diarrhea, bloating, and flatulence after ingestion of sugar are caused by

1: hydrolysis of lactose into monosaccharides.
2: deficiency of brush border oligosaccharidases.
3: decreased osmotic pressure in the colon.
4: digestion of starches in the small intestine.

Answer 54

2: deficiency of brush border oligosaccharidases.

A deficiency in brush border oligosaccharidases allows osmotically active undigested oligosaccharides to cause a shift of water into the intestinal lumen. The resulting increased pressure exerted by luminal contents increases further when colonic bacteria act on remaining oligosaccharides, thus increasing the number of osmotically active particles. Formation of CO2 and H2 from disaccharides futher increases flatulence and bloating.

Question 55

The majority of fat digestion occurs in the

1: ileum.
2: mouth.
3: colon.
4: duodenum.

Answer 55

4: duodenum.

Fat digestion begins in the mouth and stomach by lingual lipase and gastric lipase respectively, however the majority of fat digestion occurs in the duodenum by pancreatic lipase. The contribution of gastric lipase is small, but lingual lipase hydrolyzes up to 10% of dietary fat.

Question 56

All of the following hydrolyze fat in the small intestine EXCEPT

1: pancreatic lipase.
2: cholesterol ester hydrolase.
3: phospholipase.
4: bile acids.

Answer 56

4: bile acids.

Pancreatic lipase, cholesterol ester hydrolase, and phospholipase are all pancreatic enzymes involved in fat digestion. These enzymes hydrolyze triglycerides, phospholipids, cholesterol esters, and fat-soluble vitamins in the duodenum. The role of bile acids in fat digestion is to act as emulsifiers.

Question 57

A 35 year old patient with recent history of binge alcohol drinking over the holidays comes in complaining about abdominal pain which radiates to the back (has history of pancreatitis). The patient reports nausea and decrease in food intake for over one week, reports abdominal bloating, oily stools. The patient may benefit from

1: parenteral nutrition.
2: evaluation for pancreatic exocrine insufficiency.
3: maintaining NPO status until symptoms improve.
4: vitamin supplementation.

Answer 57

2: evaluation for pancreatic exocrine insufficiency.

Pancreatic exocrine deficiency may develop in patients with pancreatic diseases and may be exhibited as diarrhea, abdominal pain/distention/bloating/cramps/flatulence/weight loss. Pancreatic enzyme replacement therapy may help with improvement of digestion/nutrition/quality of life.

Question 58

Which of the following is a conditionally essential amino acid that is also a primary fuel source of enterocytes?

1: Tryptophan
2: Proline
3: Glutamine
4: Arginine

Answer 58

3: Glutamine

Glutamine is the most abundant amino acid in the body and a vital fuel for rapidly dividing cells, such as enterocytes, fibroblasts, reticuloendothelial cells and malignant cells. In some conditions, such as trauma, sepsis, and exercise, the body’s glutamine requirement exceeds the rate of synthesis leading to a decrease in plasma and intracellular glutamine. Decreased glutamine levels are associated with intestinal mucosal atrophy, impaired immune function, and decreased protein synthesis.

Question 59

A parenteral nutrition (PN) formulation contains 95 grams of protein. How many grams of nitrogen are in the PN formulation?

1: 15 grams
2: 75 grams
3: 95 grams
4: 105 grams

Answer 59

1: 15 grams

The average nitrogen content of protein was determined to be 16%. The total grams of protein multiplied by 0.16 or divided by 6.25 will determine the nitrogen content of protein in a PN solution.

Question 60

The initial daily protein requirements for a critically ill trauma patient weighing 70 kg and having a BMI of 23.4 kg/m2 are

1: 55-70 grams.
2: 70-105 grams.
3: 105-140 grams.
4: 140-175 grams.

Answer 60

3: 105-140 grams.

Because of the profound lean body mass loss that is associated with critical illness, protein needs are elevated. The current recommendation for stressed trauma patients is that 20-25% of total nutrient intake be provided as protein. This equates to roughly 1.5-2g/kg/day. Exceptions include intensive care unit patients receiving continuous renal replacement therapy and those with a BMI >30 kg/m2 should receive 2-2.5 g/kg/day.

Question 61

The primary fuel source for the brain after a 48 hour fast is

1: essential fatty acids.
2: ketone bodies.
3: carbohydrates.
4: amino acids.

Answer 61

2: ketone bodies.

The brain and red blood cells require a constant supply of glucose. The breakdown of hepatic glycogen stores (glycogenolysis) for glucose production begins within 2-3 hours of fasting, but its stores are depleted within 24 hours. Gluconeogenesis from amino acid substrate begins within 4-6 hours after the last meal. After approximately 2 days of starvation, the brain switches its fuel source from glucose to ketone bodies. The liver converts free fatty acids to ketone bodies. The adaptation to starvation with a ketone-based fuel system minimizes gluconeogenesis and further protein breakdown.

Question 62

Which protein transports oxygen from the lungs to other parts of the body?

1: Albumin
2: Hemoglobin
3: Lipoprotein
4: Retinol-binding protein

Answer 62

2: Hemoglobin

Proteins are involved in the transportation of lipids, vitamins, minerals, albumin, and oxygen throughout the body. Hemoglobin, the iron-containing protein of blood, transports oxygen from the lungs to the cells.

Question 63

The three organs in the body that have the necessary enzymes for gluconeogenesis are the liver, small intestine, and the

1: stomach.
2: gallbladder.
3: kidney.
4: pancreas.

Answer 63

3: kidney.

The liver, small intestine, and kidney all have the necessary enzymes to perform gluconeogenesis. However, the liver is the main site for this metabolic process, with the small intestine and kidney able to perform this function under certain conditions.

Question 64

The acceptable macronutrient distribution range (AMDR)

1: is defined as the Tolerable Upper Intake level for a particular energy source.
2: has been set for Omega-3 fatty acids, Omega-6 fatty acids and total fat.
3: provides a guide to assist in the treatment of chronic diseases related to fat intake.
4: is also known as the Estimated Average Requirement (EAR).

Answer 64

2: has been set for Omega-3 fatty acids, Omega-6 fatty acids and total fat.

The AMDR is defined as a range of intake for a particular energy source that is associated with a reduced risk, rather than assisting in the treatment, of chronic disease. The AMDR provides adequate intakes of essential nutrients and has been established for Omega-3 fatty acids, Omega-6 fatty acids and total fat. The Tolerable Upper Intake Level is 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. The Estimated Average Requirement (EAR) is defined as the average daily nutrient intake level estimated to meet half the needs of healthy individuals in a particular life stage and gender group.

Question 65

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

1: Corn, olive, safflower and canola oils
2: Corn, soybean, safflower and canola oils
3: Coconut, olive, palm and canola oils
4: Coconut, soybean, safflower and canola oils

Answer 65

2: Corn, soybean, safflower and canola oils

Corn, soybean, and safflower oils are rich in linoleic acid. Soybean and canola oil are good sources of α-linolenic acids. Olive, coconut, and palm oils are not good sources of linolenic or α-linolenic acids.

Question 66

The most predominant clinical change seen with essential fatty acid deficiency (EFAD) is

1: a dry, scaly rash.
2: increased susceptibility to infection.
3: impaired wound healing.
4: weight loss.

Answer 66

1: a dry, scaly rash.

While patients with EFAD can have increased susceptibility to infection, impaired wound healing, weight loss, and immune dysfunction, the most prominent clinical change is a dry, scaly rash.

Question 67

The energy for glucose transport is provided by active transport of

1: potassium into the cell.
2: potassium out of the cell.
3: sodium into the cell.
4: sodium out of the cell.

Answer 67

4: sodium out of the cell.

Glucose and sodium share common co-transporters. High concentrations of sodium in the chyme increase glucose transport. Low concentrations of sodium decrease glucose absorption. Sodium moves into mucosal cells along its concentration gradient and brings glucose along. The active transport of sodium out of the cell provides the energy for glucose transport. The transport of sodium out of the cell maintains the concentration gradient needed for sodium to shuttle more glucose into the mucosal cells.

Question 68

A 32-year-old female presents to the clinic seeking treatment for a sunburn-like rash. She has been following a low carbohydrate vegetarian diet and notes recent weight loss, diarrhea, and low energy. She reports drinking alcohol daily. Which of the following deficiencies should be considered?

1: Vitamin A
2: Vitamin K
3: Lipid
4: Niacin

Answer 68

4: Niacin

Pellagra, or niacin deficiency disease, is rare in developed nations. It presents as the “three D’s”: dermatitis, diarrhea, and dementia. Food sources of niacin include meat, fish, poultry, enriched and fortified breads, and fortified cereals. Patients with malabsorptive disorders, individuals with alcoholism, older adults, and patients on antitubercular medication isoniazid or mercaptopurine are at risk for niacin deficiency.

Question 69

Ursodiol facilitates absorption of

1: carbohydrate.
2: protein.
3: fat.
4: vitamin K.

Answer 69

3: fat.

Bile is central to the digestion of fat and is comprised of bile salts, bile pigments, cholesterol, lecithin, alkaline phosphatase, and electrolytes. Bile salts are sodium and potassium salts of bile acids, which are metabolites of cholesterol. Bile salts form micelles in which their hydrophilic portions face out and their hydrophobic portions face toward the center where lipids collect. Lipids are transported to the brush border of the intestine where they are absorbed by yet-to-be confirmed mechanisms. Ursodiol (ursodeoxycholic acid) is a form of bile acid that may potentially improve fat absorption.

Question 70

A 72-year-old female with impaired renal function was prescribed sulfamethoxazole/trimethoprim for a urinary tract infection. What electrolyte disorder is MOST likely to occur?

1: Hypermagnesemia
2: Hyperkalemia
3: Hypercalcemia
4: Hyperphosphatemia

Answer 70

2: Hyperkalemia

Although hyperkalemia can be caused by extracellular shifts of potassium and increased potassium ingestion, it most often occurs in the setting of renal insufficiency. Additionally, drugs can cause hyperkalemia. Trimethoprim induces hyperkalemia by impairing renal potassium excretion.

Question 71

First-line therapy for hyperkalemic emergencies is

1: hemodialysis.
2: regular insulin with dextrose.
3: calcium gluconate.
4: furosemide.

Answer 71

3: calcium gluconate.

First-line therapy in hyperkalemic emergencies consists of calcium gluconate 1-2 grams IV over 10 minutes, which has an effective onset time of 1-2 minutes. IV calcium gluconate should be given to symptomatic patients or those with ECG changes to restore membrane excitability to normal. Calcium acts as an antagonist to cardiac conduction abnormalities. Hemodialysis has an immediate onset, but feasibility is limited to equipment availability and individuals with existing access. Infusion of regular insulin with dextrose has a 15-45 minute onset, whereas furosemide a 5-15 minute onset.

Question 72

A patient has had a nasogastric tube to suction for 48 hours secondary to a post-operative ileus. Which of the following electrolytes will be lost?

1: Bicarbonate
2: Potassium
3: Calcium
4: Phosphorus

Answer 72

2: Potassium

Prolonged nasogastric output results in a loss of gastrointestinal secretions primarily from the stomach. Hypokalemia is a common issue with continued nasogastric output as the normal potassium concentration of gastric fluid is 10 mEq/L. Other possible electrolyte abnormalities include hyponatremia and hypochloremia. Bicarbonate, calcium and phosphorus are not directly lost from gastric suction.

Question 73

A patient in your intensive care unit has acute severe diarrhea. Which of the following acid-base disorders is likely to occur?

1: Metabolic acidosis
2: Metabolic alkalosis
3: Respiratory acidosis
4: Respiratory alkalosis

Answer 73

1: Metabolic acidosis

Diarrhea induces gastrointestinal losses of bicarbonate and can cause a metabolic acidosis (normal anion gap).

Question 74

Metastatic calcification is a complication of

1: hyperkalemia.
2: hypokalemia.
3: hyperphosphatemia.
4: hypophosphatemia.

Answer 74

3: hyperphosphatemia.

The most serious complication of hyperphosphatemia is metastatic and vascular calcification of non-skeletal tissues. This occurs when the calcium-phosphorus product exceeds 55 mg^2/dL^2. Additional consequences of hyperphosphatemia include secondary hyperparathyroidism and renal osteodystrophy.