GI L18 Malabsorption Maldigestion
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24 terms
Terms | Definitions |
|---|---|
 Maldigestion vs Malabsorption | Maldigestion: luminal phase defect in breaking down substances Malabsorption: mucosal or transport defects that prevents uptake of digested substances |
| Common causes of maldigestion | #1 = Chronic Pancreatitis (commonly caused by EtOH) -Bacterial Overgrowth -Postgastrectomy - post surgical -Bile salt deficiency |
| What causes bacterial overgrowth? | 1) Hypochlorhydria postgastrectomy or from pernicious anemia 2) altered motility due to diabetes or scleroderma 3) stasis due to structural problems (strictures, small I diverticula, blind loops) |
| Why does bac overgrowth cause maldigestion? | They deconjugate bile salts to affect fat digestion, ferment carbs, deplete B12, and can cause mucosal damage leading to flattened villi |
| Dx and Rx of bac overgrowth | Dx is difficult, gold standard is culture from intestinal aspirate, C14 D xylose breath test Rx: antibiotics, surgery |
| Common post surgical maldigestion characteristics | Common deficiencies: Iron, Vita B12, folate Issues with ineffective mixing of digestive juices, skipping duodenum skips the site of absorption of many calories, Fe, and Ca |
| Causes of bile salt deficiency | Cholestatic liver disease, bile duct obstruction, terminal ileal resection or disease |
| Fat malabsorption--clinical/lab features, test? | Fatty stools, water diarrhea, weight loss; Steatorrhea, low serum carotene Test: 72 hour collection from pt eating 100 g fat/day; normal fecal fat output < 7g/day; Sudan stain of fecal sample (only sensitive in moderate to severe steatorrhea) |
| Protein malabsorption--clinical/lab features, test? | Weight loss, muscle wasting, edema (low oncotic pressure); low albumin Test: difficult to measure and rarely done |
| Carb malabsorption--clinical/lab features, test? | Distension, flatus, borborygmi, water diarrhea; osmotic diarrhea, acid stools, positive breath tests (Bacteria in the colon are working on the carbs) Test: stool pH (acidic due to bac fermentation of malabsorbed carbs, <5.5), D-xylose test (crosses the mucous by passive diffusion, malabsorption vs maldigestion; admined at night and urine collected to see how much there is), lactose breath test |
| Bile salt malabsorption--clinical/lab features | Watery diarrhea, secretory diarrhea |
| Clinical presentation of iron, folate, vita B12, vita A, vita D, vita K, Ca, Mg, Zn deficiency | Iron, folate, B12--Glossitis, anemia, aphthous ulcers B12--Neurologic sequelae Vita A--Hyperkeratosis, night blindness Vita D--Rickets, Osteomalacia Vita K--brusing, bleeding Ca, Mg--Parestheshia, Tetany Zn--poor taste, acrodermatitis |
| Test for Vita B12 absorption | Schilling Test--also tests gastric function, ileal absorption, pancreatic function 1) PO radioactive B12 and IM nonradioactive B12 and check urine--test for malabsorption but not specific cause 2) plus intrinsic factor, check urine--test for pernicious anemia 3) plus pancreatic enzymes, check urine--test for maldigestion 4) #1/2 plus one week of antibiotics, check urine--test for bacterial overgrowth |
| What diseases cause malabsorption? | These-Tropical sprue Will-Whipple's disease Cause-Celiac sprue Devastating-Disaccharidase deficiency (commonly lactase) Absorption-Abeta lipoproteinemia Problems-Pancreatic insufficiency (technically maldigestion) |
| Celiac Sprue pathogenesis | Immune reaction in the small intestinal mucosa to gluten/gliadin --> villous flattening/atrophy of the intestinal mucosa/crypt hyperplasia. Mediated by lamina propria T-cells; starts in the duodenum and descends with increasing severity Pts also have a certain HLA type (HLA DQ2/8) May be affected by env factors: breast feeding, timing of gluten introduction, cesarean section birth, GI infections |
| Epidemiology of Celiacs | Commonly pediatric disease but can occur in 30s-40s Present in all ethnicities but common in Northern European |
| Celiac disease clinical manifestation | Classic Form: Child presenting with impaired growth, failure to thrive, diarrhea (osmotic overload), abdominal distension, flatulence, steatorrhea (less so than in chronic pancreatitis) Silent Form: wide range of clinical presentations including osteoporosis, iron/B12/folate deficient anemia, neuropathies, infertility, irritable bowel syndrome, fatigue, weight loss, dermatitis herpetiformis (blistering skin disease); Only 40% of these patients have diarrhea; this form usually has only proximal small intestinal involvement |
| Dx/Rx of celiac disease | Serological/Ab tests first (Ab to gliadin, tissue transglutaminase,false negative in IgA deficient people), hen small bowel biopsy and a clinical and histological response to removing gluten from the diet Rx: gluten free diet |
| What is Tropical sprue? Cause? | Small intestinal mucosal atrophy occurring in the "tropics": West Indies, Puerto Rico (endemic), Haiti, Dominican Republic, India, Southeast Asia Unknown etiology, but not from dietary factors, may have infectious etiology |
| Difference between Tropical Sprue and Celiac Sprue | 1) it involves the entire small intestine 2) atrophy is less severe |
| Dx and Rx of Tropical sprue | Patients from endemic area; folate or B12 deficient; Small intestine villous atrophy Rx: abx (tetracycline, sulfonamide); nutritional supplementation |
| Whipple's disease clinical presentation | non specific sx of malabsorption (diarrhea, steatorrhea, weight loss, weakness) Also: cough, fever, arthritis/arthralgia, dementia/neurologic sx, CHF common in white men 40-60 yo |
| Whipple's disease pathogenesis | Mucosal invasion with Tropheryma whippleii (Gram + bacteria) Mesenteric lymphadenopathy leads to lymphatic obstruction PAS-positive "foamy" macrophages in lamina propria, mesenteric LN |
| Dx Rx of Whipple's disease | Dx: Needs high clinical suspicion, Small bowel biopsy Tx: Bactrim (T/S) for 6 months to 1 year, Nutrient supplementation/repletion Most patients respond within 1 to 3 months but relapses common. |
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