APPROACH TO CHRONIC DIARRHOEA IN THE IMMUNOCOMPETENT PATIENT.pptx

The ppt gives more insights on how to identify and manager diarrhea in a clinical setting

1. APPROACH TO CHRONIC DIARRHOEA IN THE IMMUNOCOMPETENT PATIENT Dr Godfrey Mungwadzi MBChB, MDMD, FCP Specialist Physician & Consultant

2. DEFINITION Passage of abnormally liquid or unformed stools at an increased frequency. stool weight > 200g defined as diarrhoea Acute - < 2wks, persistent - 2-4 wks , chronic - > 4wks Distinguish this from Pseudodiarrhoea – frequent passage of small vol. of stool, often associated with rectal urgency and forms part of Irritable Bowel Syndrome Faecal incontinence – involuntary discharge of rectal contents usually caused by neuromuscular disorders or anorectal problems

3. Most causes are non-infectious and classified by pathophysiological mechanism

4. 1- Secretory Due to derangements in water and elec transport across the enterocolic mucosa Usually large vol. watery stools that are painless and persist with fasting No faecal osmotic gap, and stool osmolality is accounted for by normal endogenous elecs Medication – most common causes of secretory diarrhoea Antibiotics – Pseudomembranous colitis, NSAIDs, antihypertensives , antiarrhythmics Stimulant laxatives Chronic ethanol use – causes enterocyte injury

5. 1- Secretory Bowel resection, mucosal disease or enterocolic fistula Due to inadequate surface area for resorption of fluids and elecs Tends to worsen with eating unlike the others Also have decreased reabsorption of bile acids if terminal ileum < 100cm and this stimulates colonic secretion – cholorrheic diarrhoea Hormone Metastatic GIT carcinoids and rarely primary bronchial carcinoids may produce watery diarrhoea alone or as part of carcinoid syndrome

6. 1- Secretory 2. Gastrinomas – in up to 1/3 of cases and may be only symptom in 10% - due to pancreatic enzyme inactivation by low duodenal pH 3. VIPoma – non β cell pancreatic adenoma which secretes pancreatic polypeptide, gastrin, gastrin-inhibitory polypeptide, calcitonin and prostaglandins. Causes massive secretory diarrhoea with dehydration, low K, Mg and hypercalcaemia with neuromuscular dysfunction 4. Medullary carcinoma of the thyroid

7. 1- Secretory Congenital defects in absorption – defective Cl/HCO3 or Na/H exchange

8. 2- Osmotic Due to ingested poorly absorbable, osmotically active solute Ceases with fasting Osmotic Laxatives CHO malabsorption – due to aquired /congenital defects in brush-border disaccharidases and causes osmotic diarrhoea with low pH Lactase deficiency – one of most common causes of diarrhoea Sorbitol, Lactulose are universally malabsorbed

9. 3- STEATORRHOEAL Greasy , foul-smelling, difficult-to-flush diarrhoea often with associated weight loss and nutritional deficiencies. Defined as stool fat > 7g/d Intraluminal maldigestion Due to pancreatic exocrine insufficiency eg . in chronic pancreatitis, CF, pancreatic duct obstruction Bacterial overgrowth due to stasis from blind-loop, small bowel diverticuli or dysmotility leads to deconjugation of bile acids Cirrhosis/biliary obstruction Mucosal malabsorption Celiac sprue – villous atrophy and crypt hyperplasia in prox small bowel Tropical sprue Mycobacterium Avium Intracellulare in AIDS

10. 3- STEATORRHOEAL Infections – Giardia Medication – colchicine, cholestyramine Postmucosal lymphatic obstruction Trauma, tumor , infection

11. 4- INFLAMMATORY Generally with pain, fever and bleeding, and may have all 4 types, ie , exudative + secretory + steatorrhoea + hypermotility . Identifying feature is presence of WBC or leukocyte-derived proteins like Calprotectin in stool Can lead to anasarca Malignancy - in middle-aged or older pt Idiopathic IBD – most common organic causes of chronic diarrhoea in adults. May be associated uveitis, polyarthralgia , cholestatic liver disease and skin lesions  

12. 4- INFLAMMATORY Primary or secondary immunedeficiency – often infectious, secondary to Giardia Eosinophilic gastroenteritis Others – Radiation, Chronic GVHD, Behcet’s

13.   5- DYSMOTILE CAUSES Rapid transit may accompany other diarrhoeas and primary dysmotility is unusual Hyperthyroidism, Carcinoid, Drugs ( Pgs and prokinetic agents) Diabetic autonomic neuropathy Irritable bowel syndrome – disturbed intestinal and colonic motor and sensory responses to various stimuli. Stool frequency typically seizes at night, alternate with periods of constipation, accompanied by abd pain relieved by defecation, rarely results in weight loss or true diarrhoea

14. 6- FACTITIAL CAUSES Up to 15% of unexplained diarrhoeas