Digestion/Absorption Flashcards
how long is the duodenum
350-600 centimeters
how much fluid does the duodenum secrete
9 liters (2 liters from PO, 7 liters of gastric fluid)
role of the ileocecal valve
Prevents backsplash of colon contents into the jejunum. Closes when there is an increase in colonic pressure
complications of ileocecal valve removal
decreased B12 absorption, decreased bile salt reabsorption, rapid GI movement of the small bowel contents into the colon which can cause malabsorption
______ 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
soluble fiber
short chain fatty acids are derived from which type of fiber
soluble fiber
which type of fiber adds bulk to stool to soften it
insoluble fiber
conditions that cause gut dysbiosis
obesity, diabetes, IBD/IBS, cancer
where are sodium and water absorbed most efficiently
colon and ileum
where is fat primarily absorbed
duodenum / proximal jejunum
Primary absorption site of iron
duodenum
primary absorption site of manganese and folic acid
jejunum
Medium Chain Triglycerides are used during fat malabsorption because
they don’t have to be formed into micelles, they are water soluble and go right into circulation and don’t require bile salts.
Benefits of short chain fatty acids
inhibit cholesterol formation improve splanchnic circulation enhances immunity helper T cells inhibits pathogen growth decreases luminal pH lowers bile solubility
Primary absorption site of vitamin B 12
ileum
where are the majority of water, electrolytes and minerals absorbed
colon and small bowel
potassium and bicarobonate are secreted into the
colon
water follows sodium via this mechanism
osmosis
ileal or colonic losses from diarrhea or high output fistulas can lead to
hypokalemia, acidemia from loss of bicarbonate
most dietary iron is in the ______ form which is poorly absorbed in the gut
Ferric Fe2+
In order for iron to be absorbed, it has to change into the ______ form
Ferrous Fe3+
Which vitamin aids in the reduction of the Ferric Form (Fe2) of Iron to the Ferrous form (Fe3) of iron for easier absorption
Vitamin C (ascorbic acid)
What can be added to foods to enhance the absorption of iron in non-heme foods
Vitamin C
what amino acid provides the main fuel for enterocytes
glutamine
the absence of this amino acid can lead to mucosal atrophy
glutamine
site of primary protein digestion
duodenum
which enzymes digest protein
pepsin/pepsinogen when mixed with chyme
what amino acids are most rapidly absorbed
branched chain amino acids and essential amino acids
the primary energy source for the GI tract is ________ which has trophic effects and helps with immune function
glutamine
there is an increased need for what amino acid in critical illness
glutamine
what is the most abundant amino acid
glutamine
detriments of inadequate glutamine
GI mucosal atrophy, impaired immune function, increased risk for sepsis/bacterial translocation
which amino acids are important for the small intestine
glutamine and aspartate
what function do amino acids provide the liver
synthesis of plasma proteins: albumin, pre albumin, transferrin, clotting factors (fibrinogen/prothrombin)
The amino acid alanine is used for what in the liver
gluconeogenesis
Bile drains into the
duodenum
a disturbance of the lymphatic system in which fluid is incorrectly distributed and does NOT respond to diuretics
lymphedema
The correct dosage of IV sodium proves ___ to ___ mEq/kg of sodium
1-2 mEq/kg
normal serum sodium range
135-145
when serum sodium is low, cells are known as ______tonic
hypotonic
primary sodium losses occur from
NGT suction, fistula drainage, adrenal insufficiency
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
hypertonic hyponatremia
Primary IV treatment of hypovolemic hyponatremia
normal saline
Causes of hypovolemic hyponatremia
Third Spacing (SBO, low albumin)
Diarrhea, Vomiting, NGT suction (GI losses)
Diuretics
primary treatment of hypervolemic hyponatremia
Water restriction
causes of hypervolemic hyponatremia
CHF, Cirrhosis, TURP
primary treatment of isovolemic hyponatremia
water restriction
causes of isovolemic hyponatremia
too much IVF, water intoxication, diuretics, SIADH, drugs
the hormone released by the pituitary gland that tells your kidney how much water to conserve to maintain blood pressure by concentrating the urine
Anti Diuretic Hormone
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
SIADH (symptom on inappropriate diuretic hormone)
Etiologies of SIADH
malignant tumors, head trauma, meningitis, schizophrenia meds, post surgical
Treatment for SIADH
water restriction , sodium restriction
Acute hypotonic hyponatremia (acute water intoxication)
Sodium <125mEq/L causing headache, nausea, confusion. Na <110 mEq/L can cause seizure, coma or death
Sodium Deficit Calculation
Normal Na - Current Na x body weight in kg x % body water
Give no more than ___ free water deficit a day or > mEq/day when restricting sodium
1/2 of the free water deficit or 6-12 mEq/Day
a condition of cerebral edema (which can be deadly) in which too much sodium is given too much at one time is known as
osmotic myelinolysis
Hypertonic saline (3%) is used to treat
severe hyponatremia when a patient is confused or obtunded
when giving hypertonic saline, serum Na should be checked how often
every 1-2 hours
Don’t correct Na more than ____ to ____ a day
6-12 mEq/day
How much sodium would you replete for a 70kg male with a serum sodium of 120mEq/L with headache and confusion
126-120 x .6 x 70 kg = 252 mEq sodium
symptoms of hypernatremia
lethargy, confusion, twitching , stupor, coma
failure of the central brain to release ADH or failure of the kidneys to respond to ADH is known as
Diabetes Insipidus
Symptoms of diabetes insipidus
polyuria, polydypsia,hypernatremia , retained sodium
is sodium high or low in diabetes insipidus
high
treatment of diabetes insipidus
hypotonic fluids 0.2 or 0.45% NaCl, volume restriction, sodium restriction
the major intracellular electrolyte
potassium
normal serum range of potassium
3.5-5
typical IV dose of potassium ins mEq/kg/day
1-2 mEq/kg/day
causes of hyperkalemia
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
symptoms of hyperkalemia
EKG changes, decreased heart rate, arrthymias, high T waves, wide QRS, heart block, atrial systole, cardiac arrest, muscle cramping/twitching, weakness
What is the first step of potassium correction to stabilize the heart
calcium gluconate
What is the second step of potassium correction to shift potassium back into the cell
sodium bicarb, 100mL 50% dextrose, 10 units of insulin
Other methods to reduce potassium in hyperkalemia after calcium gluconate and correction of acidosis
dc or decrease supplemental potassium, use K sparing diuretics like Lasix, dialysis
symptoms of hypokalemia
weakness, lethargy, constipation, arrhythmia, psychosis, post op ileus, flat T waves
causes of hypokalemia
diarrhea, high urine output, metabolic alkalosis, increased amounts of insulin, catecholamines, furosemide, thiazide diuretics, sorbitol, refeeding syndrome
IV forms of potassium
potassium chloride, potassium acetate, potassium phosphorous
what type of potassium is preferred in acidosis
potassium acetate
potassium takes ___ hours to normalize
2 hours
Avoid providing IV potassium with ______ as glucose/insulin will increase forcing potassium into the cell and worsen hypokalemia
dextrose
you must correct ______ to correct potassium
magnesium
normal serum mangesium
1.8-2.8
magnesium is primarily absorbed in the
jejunum/ileum
magnesium is primarily excreted by the
kidneys
symptoms of hypomagnesemia
low potassium, tetany, decreased insulin sensitivity, arrhythmias
causes of hypomagnesemia
refeeding syndrome, decreased intake/absorption, prolonged magnesium free PN, alcoholism, ileostomy, short bowel syndrome, loop diuretics, DKA
what route of magnesium replacement is preferred
IV, oral can cause GI upset
max infusion rate of magnesium
1 gram per hour (less in renal failure)
replace magnesium with ____ in order to decrease risk of cardiac arrhythmias
potassium
causes of hypermagnesemia
chronic kidney disease and high magnesium intake/provision in EN/PN
symptoms of hypermagnesemia
nausea, diaphoresis, flushing/heat flash, bradycardia, hypotension
IV treatment for hypermagnesemia
calcium chloride or calcium gluconate
medication treatment for hypermagnesemia
loop diuretics
normal calcium range
8.6-10.2
what hormones control calcium
parathyroid hormone, vitamin D and calcitonin
the release of PTH is signaled by low _____ to increase _________, __________ and _________
calcium ; bone resorption, renal conservation, absorption in the gut
Vitamin D increases calcium by
increasing gut absorption of calcium
Calcitonin is signaled by ________ calcium to ______ osteoclast function
high calcium to decrease osteoclast formation to stop releasing calcium
Ionized Calcium normal range
1.2-1.3 mmol/L
what is the most accurate way to measure serum calcium
ionized calcium
ionized calcium is not affected by _____-
albumin
Calcium correction for hypoalbuminemia
4- serum albumin x .8 + serum calcium
etiologies of hypocalcemia
low albumin, decreased vitamin D activity, hyperphosphatemia, decreased PTH, hypomagnesemia, citrate anticoagulation in CRRT, thyroidectomy, sepsis, rhabdomyolysis, blood transfusion, bisphosphonates, furosemide, calcitonin, phenytoin
symptoms of hypocalcemia
decreased blood pressure, decreased myocardial contraction, decreased QT prolongation, extremity parenthesis, cramps, tetany
preferred IV fluid to correct hypocalcemia
calcium gluconate or calcium chloride
provide ____ to aid in calcium correction
magnesium
oral forms of calcium repletion
calcium acetate, vitamin D supplements, calcium citrate, calcium carbonate (tums)
causes of hypercalcemia
cancer, hyperparathyroidism, high vitamin D or A intake, chronic intake of milk, antacids or calcium supplements, lithium, TB, thiazide diuretics
symptoms of hypercalcemia
fatigue, nausea, vomiting, constipation, anorexia, cardiac arrhythmia, bradycardia
treatment of mild hypercalcemia
hydration and ambulation
treatment of hypercalcemia in setting of malignancy
bisphosphonates
treatment of severe hypocalcemia
lasix, hemodialysis, 1,000-1,500 mg elemental calcium, IV calcium chloride or calcium gluconate
normal range of phosphorous
2.7-4.5
functions of phosphorous
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
regulation of phosphorous
intestinal absorption, renal excretion, hormone regulation, bone resorption (deposition)
causes of phosphorous shifts
carbohydrate/insulin, catecholamines and alkalosis
symptoms of hypophosphorous
ataxia, confusion, paresthesia, hemolysis, refeeding syndrome
etiologies of low phosphorous
alcoholism, critical illness, respiratory or metabolic acidosis, DKA treatment 2/2 insulin, high CHO in TPN especially if malnourished
treatment of mild hypophosphorous
K Phos, Phos NaK
treatment of symptomatic hypo phosphorous
IV K phos or IV Na Phos
____mmol of phos = 4.4 mEq potassium
3
causes of hyperphosphatemia
CKD, ESRD, trauma, hemolysis, rhabdomyolysis, respiratory metabolic acidosis, high dose phos containing enemas
If a patient has excessive vomiting with bile they will have low
sodium and chloride
gastric juice contains ____ to ___ mEq/L of chloride
120-160 mEq chloride
bile contains ______ to ______ of sodium
120-170 mEq/L
diarrhea contains _____ to _____ mEq/L of potassium
10-60
if a patient has excessive diarrhea, they will be low in
potassium and sodium (and zinc!)
if a patient has large volumes of NGT suction what could you expect in regards to electrolyte/acid base balance
decreased chloride, decreased sodium and metabolic alkalosis
composition of lactated ringers
130 mEq sodium, 4 mEq potassium, 3 mEq calcium, 109 meQ chloride, 28 meQ bicarb will transform into acetate, lactate , 280 osmoles
which IV fluid is compositionally comparable to the jejunum
lactated ringers
composition of normal saline
154 mEq sodium 154 mEq chloride , 308 milliosmoles
composition of D5W
Dextrose 5% per liter, water, 250 mOsm
which IV fluid has the lowest osmolarity
D5W
D5W + 0.45 NaCl
Dextrose, Water, 77 mEq sodium 77 mEq chloride, 405 milliosmoles
which IVF has the highest osmolarity
D5W with 1/2 normal saline (0.45NaCl) with Potassium
where are 90-95% of bile salts re absorbed
terminal ileum
water and sodium are most efficiently absorbed here
ileum and colon
catabolism of this macronutrient is most common in stress starvation
Fat (lypolysis)
the gallbladder is stimulated by
cholecystekinin
high insulin levels suppresses this form of metabolism
lipolysis (insulin increase indicates fed state)
which enzyme starts the digestive process of carbs in the mouth
salivary amylase
homeostasis of copper is driven by
excretion
the majority of copper is absorbed by the
duodenum
phytates, zinc, iron and large vitamin C doses interfere with ___ absorption
copper
copper is excreted via
bile
oxidation/reduction reactions, electron transfer, manganese oxidation glucose metabolism, and oxidation of ferrous to ferric form of iron are roles of
copper
Copper deficiency inhibits ______ absorption
iron
deficiency of copper causes _____ deficiency
iron deficiency anemia
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
copper
copper deficiency causes _____ ____ anemia (type of RBC)
microcytic , hypochromic
populations at risk for copper deficiency
bariatric surgery, intestinal surgery, diarrhea, malabsorptive disorders
excessive copper can be secondary to _____ excretion leading to oxidative damage
impaired gallbladder (biliary)
Wilson’s disease is caused by excess ______ in the liver, typically causing liver cirrhosis
copper
hypopigmentation of the hair, Kayser Fleisher rings in the eyes, hypochromic microcytic anemia are symptoms of ____ deficiency
copper
an overdose in zinc causes ______ deficiency
copper
_____ medications decrease copper absorption
acid reducers as copper digestion relies on HCL From the stomach
Copper deficiency is common in ______ disease and requires supplementation when anemic
Celiac disease
Copper overload occurs with
parenteral nutrition 2/2 limited gall bladder stimulation for excretion
manganese is excreted by the
bile
this mineral is involved in the make up of metalloenzymes, arginase and pyruvate carboxylase
manganese
populations at risk for manganese toxicity
long term TPN
irritability, hallucinations, ataxia, and hepatic damage, Parkinson’s like symptoms, altered gait are all sings/symptoms of _____ toxicity
manganese
the content of this mineral in food depends on soil levels
selenium
thyroid alterations can occur in long term PN with out _____ supplementation
selenium
hair/nail loss, peripheral neuropathy, tooth decay and fatigue can be symptoms of ___ toxicity
selenium
selenium deficiency also concurs with ____ deficiency limiting thyroid function
iodine
this micronutrient is taken up by the thyroid to synthesize thyroid hormones
iodinne
what is the metabolically active form of thyroid hormone
T3
goiters are symptoms of ___ deficiency
iodine
increased TSH and depressed thyroid activity are results of ____ deficiency
iodine
iodine isn’t available in PN formulations. The alternative method to provide iodine in long term PN patients is
antiseptic preparations on the skin
this micronutrient is essential for glucose and lipid metabolism by mobilizing insulin
chromium
hyperglycemia is a symptom of ____ deficiency (trace mineral)
chormium
fluoride is primarily absorbed in the
stomach
functions of fluoride include
bone mineralization, hardening of tooth enamel, protects calcified tissues from demineralization, inhibits dental carries
teeth mottling, nausea/vomiting/diarrhea are all symptoms of ____ toxicity
fluoride
absorption of molybdenum occurs in
the stomach
molybedenum are excreted via the
kidneys
ultra trace elements (lead, lithium, nickel, tin etc) are elements needed in less than _____ mg /day and have no ____ or _____ determined
RDA or AI’s
now that vitamin K is added to the PN MVI, take caution with patients on this medication
Coumadin/Warfarin (monitor INR)
Parenteral trace elements
selenium, copper, manganese
in the setting of parenteral MVI/Trace element shortages, what is recommended
prioritize the most vulnerable
a patient with mental status changes (dementia) , dermatitis and diarrhea may have this deficiency
niacin deficiency (Pellagra)
manganese toxicity is common in long term PN because its route of excretion is
the gallbladder/bile
_____ toxicity occurs with cholestasis (a long term complication of PN)
manganese
extrapyramidal symptoms such as Parkinson’s like symptoms, muscle ridgitiy and tremors, and altered gait are symptoms of ____ toxicity
manganese
the most common micronutrient toxicity in long term PN regardless of liver function is
hypermanganese
if a patient exhibits cholestasis, limit these elements by providing ___ and ___ free trace elements in long term PN patients
manganese, copper
supplementation of this element may help reduce hyperglycemia
chromium
patients with significant GI losses including diarrhea are at risk for deficiency of this element
zinc
in wounds, high ostomy output and excessive diarrhea supplement with this element
zinc
serum zinc is not a reliable marker of zinc status because
it is bound to albumin which is widely available in the body
zinc and copper will not compete for absorption in
IV doses in PN
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
water, sodium,zinc
dehydration
GI losses
Zinc
headaches and Parkinson’s like activity (extrapyramidal symptoms) are a result of ____ toxicity
manganese (sometimes zinc)
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
zinc
