B5-072 CBCL: Malabsorption Flashcards
associated with enterotoxin traveler’s diarrhea
secretory diarrhea
not affected by prolonged fasting
secretory diarrhea
ceases during prolonged fast
osmotic diarrhea
what kind of diarrhea does lactase deficiency cause?
osmotic
primary functions of bile acids
- promote bile flow
- breakdown cholesterol/phospholipids in gallbladder via mixed micelles
- enhance dietary lipid digestion and absorption in proximal intestine via mixed micelles
decreased bile acid synthesis due to decreased hepatic functions
cirrhosis
decreased biliary secretion due to defective canalicular excretion of organic anions
primary billiary cirrhosis
failure of maintenance of conjugated bile acids due to bacterial overgrowth
jejunal diverticulosis
decrease in the reabsorption of bile acids due to decreased delivery to the large intestine
Crohn’s or surgical resection
results in fatty acid diarrhea
bile acid diarrhea is due to […] ileal disease
limited
fatty acid diarhhea is due to […] ileal disease
extensive
in fatty acid diarrhea, the fecal-bile acid loss is not compensated by hepatic synthesis causing in impaired micelle formation and resulting in
steatorrhea
does bile acid diarrhea respond to cholestyramine?
yes
does fatty acid diarrhea respond to cholestyramine?
no
can make it worse
does bile acid diarrhea respond to a low fat diet?
no
does fatty acid diarrhea respond to a low fat diet?
yes
dietary fat is composed exclusively of
long chain triglycerides
assimilation of dietary lipids requires 3 phases:
- intraluminal (digestive)
- mucosal (absorptive)
- delivery (post absorptive)
abnormality of any of these may cause steatorrhea
an issue in the digestive phase with lipolysis due to decreased pancreatic lipase
2
can be due to gastrinoma or increased bicarb
chronic pancreatitis
cystic fibrosis
an issue in the absorptive phase with mucosal uptake and re-esterfication due to impaired movement of mixed micelles
can be due to bacterial overgrowth
celiac
issue in the post-absorptive phase with chylomicron formation due to impaired synthesis of B-lipoproteins
Abetalipoproteinemia
issue in the post absorptive phase with lipid delivery from the intestine due to abnormal intestinal lymphatics
intestinal lymphangiectasia
- present in coconut oil
- often used as nutritional supplement
medium chain fatty acids
is micelle formation necessary for the digestion of MCTs?
no
absorbed directly into cell
- synthesized by colon bacterial enzyme from non-absorbed carbohydrates
- rapidly absorbed and stimulat colon NaCl and fluid absorption
short chain fatty acids
most antibiotic diarrhea (except C. diff) is caused by a suppression of colonic bacteria resulting in a decrease of
SCFAs
lactose requires digestion by
brush border lactase
only clinical important disorder of carbohydrate absorption
lactose malabsorption
genetically determined decrease or absence of lactase while all other aspects of intestinal absorption and brush border enzymes are normal
primary lactase deficiency
caused by diseases that destroy the lining fo the small intestine along with the enzymes
secondary lactase deficiency
secondary lactase deficiency is often see in what conditions?
4
- celiac
- crohn’s
- UC
- chemo/long antibiotics
persistence of symptoms in an individual who exhibits lactose intolerance after adhering to a strict lactose free diet indicates
IBS
most individuals with primary lactase deficiency do not have
symptoms
due to a congenital absence of brush border SGLT1
glucose and galactose malabsorption
due to absence of the enzyme that converts trypsin to trypsinogen
enterokinase deficiency
associated with diarrhea, growth retardation, and hypoproteinemia
enterokinase deficiency
- due to a defect in nonpolar amino acids
- pellagra-like rash, neuropsych symptoms
hartnup’s syndrome
- due to a defect in dibasic amino acid transport
- renal calculi and chronic pancreatitis
cystinuria
symptoms of malabsorption in a patient who has recently undergone bowel resection
short gut syndrome
steatorrhea in a patient with longstanding alcohol abuse and chronic pancreatitis
assess pancreatic exocrine function
gold standard in establishing a diagnosis for steatorrhea
timed quantitative stool-fat determination
qualitative test for steatorrhea
Sudan III staining
rapid and inexpensive but not as precise
what laboratory studies should be ordered in a patient with suspected malabsorption disorder?
CBC
PTT
serum protein
alkaline phosphatase
fat soluble vitamins
ADEK
evidence of metabolic bone disease with elevated alkaline phosphatase and/or reduced calcium
vitamin D malabsorption
elevated PTT in an individual without liver disease that is not taking anti-coags might indicate
vitamin K deficiency
macrocytic anemia might indicate
cobalmin or folic acid malabsoprtion
iron deficiency anemia in the absence of occult bleeding might indicate
2
iron malabsorption
celiac
- test performed to determine the cause of cobalamin malabsorption
- establishes pernicious anemia
Schilling
- test to assess proximal small-intestinal mucosal function
- reflects duodenal/jejunal mucosal disease
urinary d-Xylose test
- autoimmune disorder
- reaction to gluten
- causes malabsorption
celiac
- anemia
- osteopenia
- infertility
- neurologic symptoms
may indicate…
atypical celiac disease
- abnormal small-intestinal biopsy with proximal-to-distal severity
- responds to elimination of gluten from diet
celiac
absence of HLA-DQ2/8 excludes the diagnosis of
celiac
association with gliadin
celiac
a 4 week course of […] can induce remission in celiacs
prednisolone
failure to responds to all treatments of celiac may indicate
intestinal T cell lymphoma
autoimmune enteropathy
associated diseases with celiac
- dermatitis herpetiformis
- DM1
- IgA deficiency
- Down syndrome
- Turner’s syndrome
3 situations that may mandate intestinal resection
- mesenteric vascular disease
- Crohn’s
- trauma
most bile acids are reabosorbed in the
ileum
- abdominal pain
- fever
- weight loss
- increased bile acids in large intestine
crohns
bacterial overgrowth in the small intestine will results in a fast conversion of […] bile acids to […] bile acids
conjugated to
unconjugated
- leads to increases in the thickness of the unstirred water layer in the small intestine
- results in impaired movement of mixed micelles aross
bacterial overgrowth syndromes
- steatorrhea due to abnormal intestinal lymphatics
- deficiency in delivery of digested fatty acids from the intestine to the lymphatics
intestinal lymphangiectasia
- failure to thrive
- photosensitivity
- intermittent ataxia
- nystagmus
- tremor
Hartnup syndrome
defect in transport of neutral amino acids
hartnup syndrome
- characterized by deficienct transport of tryptophan
- pellagra-like rash
- neuropsych symptoms
hartnup syndrome
deficiency in chylomicron formation due to impaired synthesis of B-lipoproteins
abetapoproteinemia
defect in transport of dibasic amino acids
cystinuria
due to absence of brush border enzyme that converts trypsinogen to trypsin
enterokinase deficiency
test performed for pernicious anemia
Schilling
B12 deficiency
- depression
- irritability
- abnormal sensations
- poor muscle function
- glossitis
- decreased taste
symptoms of B12 deficiency
performed to diagnose conditions that prevent the small intestine from absorbing nutrients in food
urinary D xylose
flat small intestinal mucosal biopsy
celiac
will celiac have a positive D-xylose test?
yes
things necessary to establish celiac diagnosis
- improvement of symptoms on gluten free diet
- antibody test
- biopsy of small intestine
secondary to diminished absorption of one or more dietary nutrients
osmotic diarrhea
condition when stool fat excretion increases >6% of dietary fat intake
steatorrhea
diarrhea due to small or large intestinal fluid and electrolyte secretion
secretory diarrhea
what kind of diarrhea would cease during a prolonged fast?
osmotic
cobalamin and bile acids are absorbed in the
ileum
calcium, iron, and folic acid are absorbed in the
proximal small intestine
especially duodenum
why does steatorrhea not generally occur in short bowel syndrome?
hepatic synthesis of bile acid increases to compensate for the rate for fecal bile acid losses
[…] develops if the degree of ileum resected is extensive
fatty acid diarrhea
hepatic synthesis can no longer maintain bile acid pool
steatorrhea with decreased pancreatic lipase secretion
chronic pancreatitis
deficiency in delivery of digested fatty acids from the intestine to the lymphatic vesicles
intestinal lymphangiectasia
steatorrhea results from impaired synthesis of B-lipoproteins and impaired chylomicron function
abetalipoproteinemia
steattorhea occurs due to increased thickness of unstirred water layer in small intestine and impaired movement of micelles
bacterial overgrowth syndromes
catalyzes the hydrolysis of starch into sugars
pancreatic amylase
SGLT1 transports..
glucose
galactose
fructose comes into the cell via facillitated diffusion with what transporter?
GLUT5
- bowed legs
- bone pain
- trouble sleeping
- elevated alk phos
suggests what deficiency
vitamin D
macrocytic anemia suggests what deficiency
cobalamin or folic acid
elevated PTT suggests what deficiency
vitamin K
- weight loss
- diarrhea
- joint pain
- arthritis
- foamy macrophages in lamina propria
whipple’s
foamy macrophages in lamina propria that are seen on acid-Schiff staining
whipple’s
- short/absent villi
- mononuclear infiltrate
- epithelial cell damage
- hypertrophy of crypts
celiac
responds to pancreatic enzyme treatment
chronic pancreatitis
which HLA types are associated with celiac?
HLA-DQ2
HLA-DQ8
changes in intestinal anatomy leading to anatomic stasis can cause
bacterial overgrowth syndrome
direct communication between the small bowel and large intestine can cause
due to ileocolonic resection
bacterial overgrowth syndrome
impaired peristalsis leading to functional stasis can cause
bacterial overgrowth syndrome
most common bacteria in SIBO
bacteroides or E. coli
bile acid diarrhea in the absence of ileal inflammation/resection will have an abnormal […] study
755eHCAT retention
bile acid diarrhea in the absence of ileal inflammation/resection will have an reduced ileal release of […]
FGF19
(negative regulator of bile acid synthesis )
causes excessive bile acid synthesis
diarrhea in patient with abnormal 755eHCAT retention and reduced FGF19 will responsd to
cholestyramine
persistent of lacose intolerance symptoms even after elminating lactose from diet may indicate
IBS
defect in transport of dibasic amino acids
cystinuria
associated with renal calculi and chronic pancreatitis
cystinuria
what vitamin deficiencies does celiac often present with?
iron
folate
vitamin D
Ca+
what condition is a celiac particularly at risk for?
osteoporosis
what is the underlying cause of malabsorption in SIBO?
deconjugation of bile acid, preventing reabsorption in ileum and depleting normal bile acid pool
what deficiency can cause neuropathies and sensory ataxia
B12
what deficiency can cause night blindness?
vitamin A
what deficiency can cause hypocalcemia?
vitamin D
what deficiency can cause nerve and muscle damage resulting loss of body movement control, weakness, vision problems, and weakened immune system?
vitamin E
what deficiency can cause anemia?
iron, B12
what deficiency can cause beriberi?
B1
what deficiency can cause pellagra?
B3
patients with celiac may be deficient in […] because they are often found in wheat products
B vitamins
dietary fat is usually composed of
long chain triglycerides
synthesized by colonic enzymes from unabsorbed carbohydrates
short chain triglycerides
digestion of long chain triglycerides requires
pancreatic lipolysis and micelle formation
medium/short chain triglycerides do not require
lipolysis
steatorrhea is defined as a condition when stool fat excretion increases to what percentage?
> 7%
what kind of diarrhea will not respond to a prolonged fast?
secretory
gram positive actinobacteria
T. whipplei
both anatomical and functional stasis can contribute to
bacterial overgrowth syndromes
initial treatment of short-bowel syndrome includes
- establishing effective diet
- judicious use of opiates to reduce stool output
removal of the ileocecal valve causes severed diarrhea due to
3
- increased bile acids
- decreased transit time
- bacterial overgrowth from colon
test used to determine intestinal lesions, as well as cellular and histological abnormalities
biopsy of small intestine mucosa
test for pernicious anemia
detects cobalamin malabsorption
schilling test
test for carbohydrate absorption
D-xylose test
what deficiency can cause night blindness, dry kin, dry eyes, frequenct infections?
vitamin A
what deficiency can cause macrocytic anemia?
cobalamin
what deficiency can cause elevated alk phos and reduced calcium levels?
vitamin D
absence of SGLT1 causes malabsorption of
glucose
galactose
fructose is absorbed by
GLUT5
most individuals with lacotse deficiency do not have
symptoms
chronic pancreatitis patients often develop steatorrhea due to impairment of
lipolysis
removes bile acids by forming insoluble complexes with bile acids to be excreted in feces
cholestyramine
steatorrhea in bacterial overgrowth syndrome is a result of
failure to maintain duodenal conjugated bile acid concentrations
conjugate bile acids have a lower crictical micellar concentration than unconjugates and area more effective in
micelle formation
bile acids are absorbed in the
ileum
