{"type":"rich","version":"1.0","provider_name":"Transistor","provider_url":"https://transistor.fm","author_name":"Board Pearls","title":"Chapter 12, Ep 1 of 2: Framework and Mechanism Workup","html":"","width":"100%","height":180,"duration":1115,"description":"Chronic diarrhea is too much stool water, and because normal absorptive efficiency runs near ninety-nine percent, small physiologic insults produce large clinical phenotypes. Episode one builds the four-mechanism framework, osmotic, secretory, fatty, and inflammatory, and lets that mechanism drive a staged workup. History, basic labs, stool studies, and endoscopy sort most patients within a few tests toward a targeted second-stage evaluation.\n \nTopics covered\n\nFour mechanism categories of chronic diarrhea\nStool osmotic gap calculation and cutoffs\nHistory, medication, and surgical review\nBasic labs and celiac serology with total IgA\nStool studies: calprotectin, elastase, fecal fat\nIBS-D overlap traps\nSecretory workup and neuroendocrine tumors\nFatty diarrhea: maldigestion versus malabsorption\n \n \nKey decisions\n\nOsmotic gap is 290 minus twice the sum of stool sodium and potassium; under 50 is secretory, over 100 is osmotic, in between is mixed.\nOrder total IgA with celiac serology because IgA deficiency invalidates the IgA-based test, the single most common workup error.\nCollect a formed stool for fecal elastase because a watery sample falsely lowers it; a low value supports pancreatic insufficiency.\nHold acid blockers for a week before gastrin and chromogranin A because PPIs raise both and cause false positives.\nRandom biopsies of normal-looking colon are mandatory in older patients with chronic watery diarrhea to catch microscopic colitis.\nAfter cholecystectomy or ileal resection, an empiric cholestyramine trial for bile acid malabsorption is diagnostic and therapeutic in one step.\n \n \nThis is an AI-generated podcast, and some pronunciations may be imperfect. Thank you for your understanding, and we hope you enjoyed this content.\n \n \nStudy the full chapter on Board Pearls, with practice questions, tables and primary-guideline references: Chronic Diarrhea and Malabsorption\nRead this episode: boardpearls.com/gi/episodes/chronic-diarrhea-and-malabsorption-ep1...","thumbnail_url":"https://img.transistorcdn.com/-FuAdDBcPDLhEoUmroZKtOBRvuBn_FHPpYlh41hOnU4/rs:fill:0:0:1/w:400/h:400/q:60/mb:500000/aHR0cHM6Ly9pbWct/dXBsb2FkLXByb2R1/Y3Rpb24udHJhbnNp/c3Rvci5mbS9iNzlh/ZTU4Y2MzNWExMjQ5/MjA5OWMwMmI3ZTk5/NGFiZS5wbmc.webp","thumbnail_width":300,"thumbnail_height":300}