L5-Diarrhea Year 4 Paediatrics Notes OmpathStudy

L5-Diarrhea Year 4 · Paediatrics Collection: 4TH YEAR ALL NOTES / PAEDS / OTHER NOTES -- Lecture 5:\nDiarrhea\n\n Done by: Fatimah AlQarni\nRevised by: Mohammed Alnafisah\nTeam leaders: Abdulrahman Al-Thaqib & Maha Alzeheary \n\n Objectives Upon completion of this lecture the students should: 1. Describe the pathophysiology and causes of various types of\ndiarrhea (Secretory, osmotic, Exudative, Motility-related) 2. Define acute diarrhea and enumerate its common causes 3. Define chronic diarrhea and enumerate its common causes\n\n Contact us: Pathology433@gmail.com \n@pathology433 \n\nDefinition:\nThe condition of passing at least 3 loose or liquid stools per day.\n( 200-300 gm/day )\n- Mostly affect children.\n\nClassification depends on pathophysiology:\n1. Secretory\n2. Osmotic\n3. Exudative (inflammatory )\n4. Motility-related\n\nClassification depends on severity: \n1. Acute diarrhea.\n2. Persistent diarrhea.\n3. Chronic diarrhea. \n\nCategories of diarrhea depends on pathophysiology: 1. Osmotic diarrhea: Excessive poorly absorbed substances → ↑ osmotic pressure → water is drawn into lumen → osmotic diarrhea. Characteristic: 1. Stool output is usually not massive. 2. Fasting improve the condition (‫)ألن الطعام داخل األمعاء يقل وتبعًا لها تقل األوسموالرتي‬. Causes: 1. Malabsorption such as lactose intolerance, celiac disease. 2. Osmotic laxatives ‫ ↑( ملينات‬osmotic pressure). 3. Hexitols (poorly absorbed sugar found mostly in gum, such as sorbitol, mannitol, xylitol.) 4. Giardiasis (loss of brush border → ↓ absorption) 5. Disaccharidase deficiency (so the sugar will be non-absorpable) Screening test: Fecal smear for leukocytes: negative. Stool osmotic gap 125 mOsm/kg ( loss of hypotonic fluid) Differentiation between Osmotic diarrhea and Secretory diarrhea by\nFecal osmolarity: Fecal osmolality is equal to the serum osmolality ( = 290 mosm\kg) -. Normally, the major osmoles are Na+, K+, Cl–, and HCO3–.\n- Normal fecal fluid values ( Na+: ~30 mmol/L K+: ~75 mmol/L ) Stool osmotic gap = stool osmolality – 2 x (stool Na+ + stool K+)\n→ if it’s 125 → osmotic diarrhea\n→ if it’s <100 → secretory diarrhea \n\nCategories of diarrhea depends on pathophysiology: 2. Secretory diarrhea: An increase in the active secretion of water. Characteristics: 1. High stool output. 2. Loss of Isotonic fluid. 3. Lack of response to fasting (because it’s not related to osmosis). Causes: 1. The most common cause is the bacterial toxins (E.coli, cholera) that stimulate the\nsecretion of anions. 2. Enteropathogenic virus e.g. rotavirus & Norwalk virus 3. Neuroendocrine tumors such as carcinoid tumor1 & gastrinomas2 4. Rectal villous adenoma (increase the absorptive surface area → ↑ secretion). Screening test: 1. Fecal smear for leukocyte: negative -. 2. Stool osmotic gap < 100 mOsm/kg 3. Measure the 5-HIAA3 (the main metabolite of serotonin) to exclude the carcinoid\ntumor. Note: there is no invasion of the mucosa of intestine (that’s how we differentiate secretory diarrhea from exudative diarrhea). \n1: (serotonin-secreting tumor in small or large intestine → ↑ ion secretion)\n2: gastrin-secreting tumor found in duodenum and pancreas → ↑ HCL → ulceration of small\nintestine → ↑ secretin → diarrhea)\n3: 5-Hydroxyindoleacetic acid \n\n Categories of diarrhea depends on pathophysiology: 3. Exudative (inflammatory) diarrhea:\n- outpouring ‫ تدفق‬of blood protein, or mucus from an inflamed or ulcerated mucosa\n→ Presence of blood and pus in the stool (usually loose stool)\nCharacteristics:\n1. Persist on fasting\n2. Bacterial dysentery (bloody diarrhea with mucus due to infection or IBD).\nCauses:\n1. Invasive bacterial infection, the main organism are:\n Campylobacter which invades mucosa in the jejunum, ileum & colon.\n Salmonella typhi, S. paratyphi A, B, and C.\n Shigella infections: are mainly seen in young children.\n Enteroinvasive & Enterohemorrhagic E. coli\n Entamoeba histolytica (Picture) \n2. Inflammatory bowel disease (IBD). \nScreening test:\n1. Fecal smear for leukocytes: positive +.\n2. Stool culture for ova & parasites. \n4. Motility-related diarrhea:\nRapid movement of food through the intestines (hypermotility).\nCauses:\nIrritable bowel syndrome (IBS): a motor disorder that causes abdominal pain and\naltered bowel habits with diarrhea predominating. \n\nClassification depends on severity: 1. Acute diarrhea: Duration: Less than 2 weeks. -Causes: 1. Infections (bacteria, viruses, helminths & protozoa).\nA. viral gastroenteritis:\nis the most common cause of acute diarrhea worldwide.\nrotavirus Usually caused by rotavirus (commonly in children).\nb. - Antibiotic-associated diarrhea (pics): Occurs in 20% of patients receiving broad-spectrum antibiotics. 20% of these diarrheas are due to clostridium difficile which lead to\npseudomembranous colitis ( ‫ تقوم بصنع غشاء كاذب على األمعاء يتكون من‬neutrophils,dead\nepithelial and inflammatory debris) (antibiotic will lead to overgrowth of the organism → ulceration & ne