Chronic Diarrhea and Malabsorption Year 4 Internal Medicine

Chronic Diarrhea and Malabsorption Year 4 · Internal Medicine Collection: 4TH YEAR ALL NOTES / IMED / I MED BEAUTIFUL NOTES / GIT -- ● Objectives: To have an overview regarding chronic diarrhea:\n● Definition - Pathophysiology - Classification - Approach To discuss common causes of chronic diarrhea:\n● Celiac Disease - Whipple Disease - Tropical Sprue - Small Bowel Bacterial Overgrowth\n● Exocrine Pancreatic Insufficiency - Bile Salt-Induced Diarrhea\n\n [ Color index: ​Important​ ​Notes ​ ​Extra​ ]\n[​ ​Editing file​ ​ ​ ​Feedback​ ​ ​Share your notes​ ​ ​Shared notes​ ​ ​Twitter​ ] \n● Resources:\n● 435 slides and notes. For ​Further reading: ​here\n\n ● Done by:​ ​Luluh Alzeghayer & Hassan Albeladi\n● Team sub-leader:​ ​Jwaher Alharbi\n● Team leaders:​ ​Khawla AlAmmari & Fahad AlAbdullatif\n● Revised by:​ Ahmad Alyahya \n\n Objective 1- To have an overview regarding chronic diarrhea:\n★ If you don't have time to study this lecture, ​click here Definitions:\n● Diarrhea: ​Stool output that exceeds ​200-300 ml/day​ is considered\ndiarrhea \norganic causes​ of diarrhea have to be distinguished from ​functional\ncauses​ (Frequent passage of small volume of stools with stool weights\n< 250g)​ Exception distal colon cancer and procitis are organic causes\nthat present with stool frequency and normal stool volume\nFirst of all any patient presents with diarrhea you have to ​exclude\nInfection​! By stool cultures and flexible sigmoidoscopy with colonic\nbiopsy if symptoms persist and no diagnosis has been made.\n● Acute​: ​common and usually transient, self-limited, Infection related​.\n(less than 2 weeks): the most common cause is infections.\n● Subacute (between 2-4 weeks).\n● Chronic​: ​A decrease in fecal consistency lasting for 4 weeks or more,\nusually requires work up,​ ​(More than 4 weeks): infectious organism is a cause but you should rule out other causes\n(you should not expect IBD or IBS to cause acute diarrhea, because they are associated with chronic diarrhea).\n● Maldigestion: inadequate breakdown of triglycerides\n● digestion is converting large particles into small particles in the lumen\n● Either secretory insufficiency, impaired motility or abnormal enzymes\n● Malabsorption: inadequate mucosal transport of digestion products\n● absorption is the transition of nutrients from the lumen to portal vein or lymphatics\n● Either mucosal disease, lymphatics or vascular disease\n● Fecal Osmotic Gap (FOG)=​ 290 ​(plasma osmolality)​ − 2 X (stool ​Na ​+ stool ​K​):\n➔ FOG of 50 mosm/kg is suggestive of an ​osmotic diarrhea​ and a gap of 100 mosm/kg is more specific. \n​( 100 = osmotic “MCQs!!!!!!”) \n● Tip to differentiate between osmotic and secretory diarrhea is whither it is affected by fasting or not, osmotic diarrhea\nwill improve (relieved) with fasting (you will not retain fluids if you didn't take osmotic argents) but if you have an\ninfection you will have diarrhea that is not related to fasting. Another way to differentiate between them: fecal\nosmotic gap. 290 is the osmolality of the serum which should be equal to the osmolality of the stool.\n\nPathophysiology:\nEach day, 9–10 L of fluid enter the jejunum. ● Small intestine absorbs 90% of this fluid load. ● The colon absorbs ​90% of the remaining load​ (about 900 ml/24 hours); leaving approximately​ 80–100 ml\nexcreted each day in feces. ​around 900 ml get absorbed in the colon (1L) = small amount diarrhea. ● A normal colon can ​compensate​ by absorbing up to 3000–4000 ml/24 hours ​if there is diarrhea due to small\nintestinal disease\n★ Most of absorption occurs in small bowel, therefore; ​small\nbowel disease ​large ​volume diarrhea, and l​ arge ​bowel\ndisease ​small ​volume diarrhea. \n\n Classification of Diarrhea:​ ​(According to Mechanism): \nDiarrhea Description, causes and examples 1.Watery: A- Osmotic B- Secretory Overview ➢ Excess amount of​ poorly absorbed ➢ Malabsorption or secretion of electrolytes and\nsubstances​ that is osmotically active water\nremain in the intestine and exert ➢ High stool output: Large volume ( 1 L/d).\nosmotic effect​ ​ obligate retention of ➢ Mainly in intestinal diseases\nwater within the lumen diarrhea. Effect of fasting ➢ Fasting improve the condition ➢ Lack of response to fasting​. (by history) (Diarrhea is relieved by fasting and gets\nworse with eating). FOG ➢ Fecal osmotic gap (​FOG) of 50 ➢ Low fecal osmotic gap: ​< 50 mOsm/kg is\nmosm/kg is suggestive of an osmotic suggestive of diagnosis with secretory diarrhea,\ndiarrhea and a gap of 100 mosm/kg is < 25 mOsm/kg is definitive​ ​(loss of isotonic\nmore specific​ “more definitive for fluid)​.\ndiagnosis”​ ​(there is loss of hypotonic\nfluid) Causes It has a broad DDX, including:..\n➢ Malabsorption due to​ loss of ● Infections:​ ​The most common cause of this\nnutrient transporter e.g. lactase type of diarrhea is a​ ​bacterial toxin​ e.g​. (some\ndeficiency,​ celiac disease​. ​Lactose is types of E. coli, cholera) that stimulates the\nosmotically