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Malabsorption
Gastroenterology
Question | Answer |
---|---|
In pts≥ 40 years with chronic diarrhea, always consider: | colon cancer |
Causes of chronic diarrhea | abnormal ion transport: dec absorption, inc secretion (meds, bowel resection); non-absorbable molecules (osmotic laxatives, lactose intolerance, Mg, sorbitol); inflammation (UC); abnormal intestinal motility |
chronic diarrhea & weight loss +/- nutritional deficiencies = | malabsorption |
chronic bloody diarrhea = | UC (wt loss, other systemic sx) |
chronic diarrhea without nutritional deficiencies = | lactose intolerance, IBS, laxative overuse |
TOC for malabsorption | Sudan stain for fecal fat (25% false neg) |
D-xylose: | identifies mucosal malabsorption in small bowel |
Hydrogen breath test: most useful for: | diagnosing lactase deficiency |
Celiac dz: classic presentation: | sx can be protean; classic = diarrhea with steatorrhea, weight loss, nutritional deficiencies (in children, add FTF); may mimic IBS/travelers; other GI sx: distention, flatulence, borborygmi |
Celiac EIMs | Short; fatigue, amenorrhea, dec fertility; osteopenia, osteoporosis; arthropathy; Fe def anemia; folate, vitamin K deficiency |
Celiac dx S/S depend on: | length of sm bowel involved & age at which disease presents |
Pts w/ mild proximal Celiac dz may have: | only anemia and osteoporosis without any GI symptoms |
Pts w/ sig distal Celiac dz & mucosal involvement: | usually have persistent diarrhea |
Intensely pruritic papulovesicular rash of trunk, scalp and extremities = | Dermatitis herpetiformis |
PE for celiac dz: | check teeth for loss of enamel; mx atrophy; kyphosis; bruises; inc abd sx (bloating, abd pain, chronic diarrhea, IBS-like sx); EIM (wt loss, fatigue, arthralgias, skin lesions) |
Celiac dz labs | CBC, PT; iron, B12 and folate; Ca alk phos, alb; beta-carotene; ESR; Stool exam: Giardia, C. diff; quantitative or qualitative fecal fat (in patients with chronic diarrhea) |
Most specific serologic test for celiac: | anti-endomysial Ab |
TOC (cheaper, less tech difficult) for celiac: | anti-tGA (total IgA & genetic tests may also be indicated) |
Gold std for celiac testing | mucosal bx (even if pos serologies) |
Mucosal bx: pathognomonic findings: | villous atrophy; lymphocytic infiltration of lamina propria; crypt hyperplasia; inc intraepithelial lymphocytes |
Celiac dz Tx | gluten free diet is curative |
Celiac dz: complications | Malig (lymphoma); also esoph (SC) ca; colon & hepatocell ca; other autoimmune; nutrition def; Musculoskel injuries |
Most common malig assoc w/celiac: | lymphoma |
Inflam dz sm bowel 2/2 overgrowth of coliforms = | Tropical sprue |
Tropical sprue: dx & tx: | diarrhea, megaloblastic anemia; tx = extended Abx tx; folate, B12 supplementation (B12/megalo anemia usu not part of celiac dz) |
Whipple dz: 2 stages: | prodromal & steady-state |
Whipple: Dx | arthralgias; GI sx; wt loss, chronic cough, low-grade fever, neuro sx (steady-state: wt loss & diarrhea); bx is confirmatory (villous atrophy, macrophage infiltration of lamina propria); tx = prolonged antibiotic therapy |
Whipple: in DDx of: | inflammatory arthropathies; any conn tissue dz; malabsorption with small bowel involvement; neurologic disease |
Overgrowth of bacteria in small bowel can cause: | malabsorption |
Overgrowth of bacteria: poss causes | gastric achlorhydria (PPIs); impaired motility of small bowel; anatomic abnormalities |
Weight loss, recurrent greasy stools (steatorrhea) mixed with diarrhea after certain foods | Celiac Sprue |
Anti-endomysial antibodies | Celiac Sprue |
Beriberi | Thiamine (B1) deficiency; Alcoholics, Neuro Sx +/- cardiomyopathy, CHF |
Pellagra (raw skin) | Niacin (B3) (4D’s dermatitis, diarrhea, dementia, death), bright red tongue |
Scurvy | Vit C (easy bleeding, bruising, hair & tooth loss, joint pain and swelling) |
Rickets; hsm, lg skull, genu varus/ valgus | Vit D (Osteomalacia) |
Night blindness; Xerosis, Hyperkeratinization, Loss of taste, Bitot spots (white spots on conjunctiva) | Vit A deficiency; secondary causes antiseizure meds, low Ca |
Magenta tongue | Riboflavin deficiency (B2) |
decreased proprioception and vibratory sense, gait disturbance, possibly 2/2 deficiency of: | Vit E; secondary causes CF, biliary atresia, Cholestatic liver dz |
Dermatitis, Neuropathy, Stomatitis, Cheilosis | vit B complex def (most often 2/2 EtOH) |
uncommon causes of B3 def | INH use, Hartnup dz, carcinoid |
B1 (thiamine)def sxs | impaired jejunal/ileal absorption; beri beri; Wernicke-Korsakoff |
HLA-DQ2, HLA-DQ8 association | celiac dz |
assoc w/celiac dz | dermatitis herpetiformis; Type 1 DM; autoimmune thyroid dz; RA; Sjögren; Down syndrome; poss CHD, sarcoid, CF, IBD, autoimmune hep, MG |
celiac dz physical exam | check for loss of enamel; mx atrophy; kyphosis; bruises; +abdominal signs |
villous atrophy, lymphocytic infiltration of lamina propria, crypt hyperplasia, inc intraepithelial lymphocytes = | celiac dz |
Intensely pruritic papulovesicular rash of trunk, scalp and extremities = | Dermatitis herpetiformis (think celiac dz) |
B12 and colesterol are absorbed only at the: | terminal ileum |
If no sx improvement for celiac dz with gluten free diet, consider: | alternate dx (lymphoma, Giardia, pancreatic insufficiency, lactose intolerance). Most common reason for GFD tx failure is incomplete dietary gluten removal |
malabsorption: impaired digestion = ___ phase | intraluminal phase |
malabsorption: impaired absorption = ___ phase | mucosal phase |
malabsorption: impaired transit = ___ phase | absorptive (transport) phase |
If quantitative fecal fat is abnormal, and D-xylose test is normal: disease is: | pancreatic disease (or bile salt deficiency) |
If quantitative fecal fat is abnormal, and D-xylose test is abnormal: disease is: | mucosal disease |
When urinary D-xylose is abnormal, test for bacterial overgrowth with this test | breath hydrogen test (after a glucose challenge) |
If breath hydrogen test does not reveal bacterial overgrowth, next step is: | mucosal bx |
Bacterial overgrowth (SBBO) is associated with impairment of (3): | gastric acidity, peristalsis, or intestinal immunoglobulins (IgA) |
Secretory diarrhea MOA | Elevated cAMP, cGMP, and/or Ca inhibit NaCl absorption and induce Cl secretion; H2O follows and accumulates in gut lumen => dehydration |
3 characteristics of secretory diarrhea | 1) high volume, 2) persist during fasting, 3) low stool osmotic gap (diff btw stool osmolality and lytes osmo) |