Diarrhoea-biochemistsnov05.pptVIP

Investigation of chronic diarrhoeaBritish Society of GastroenterologyGuidelines 2nd Edition 2003  Dr. P.D. Thomas Consultant Gastroenterologist Taunton and Somerset Hospital Outline Definitions Initial assessment Factitious diarrhoea Functional bowel problems Colonic investigations Small bowel investigations Investigation of fat and carbohydrate malabsorption Investigation of malabsorption due to pancreatic insufficiency Specific conditions small bowel bacterial overgrowth, bile salt malabsorption, hormone secreting tumours Mechanisms Intestinal secretions and food- 7l per day 5L absorbed in small intestine 1.5-2L absorbed by colon Stool 100-200mL water 10% decrease in fluid absorbed by colon will double stool volume Considerable reserve capacity of colon to absorb increased ileal effluent Approaches to the classification of diarrhoea Distinguishing osmotic from secretory diarrhoea - fasting - osmotic diarrhoea should stop - osmotic gap low stool osmolality 290 mosmol/kg suggests contamination with hypotonic fluid 290-2x (Na and K conc) Osmotic gap 125mosmol/kg osmotic diarrhoea 50 in secretory diarrhoea Anatomical …... Causes of diarrhoea Colonic Colonic neoplasia Endocrine Ulcerative and Crohns colitis Hyperthyroidism Microscopic colitis Diabetes Small bowel Hypoparathyroidism Coeliac disease Addisons disease Crohns disease Hormone secreting tumours (VIPoma, Other small bowel enteropathies, gastrinoma, carcinoid) (e.g. Whipples disease, tropical sprue, amyloid, intestinal lymphangiectasia ) Bile Acid malabsorption Disaccharidase deficiency Small bowel bacterial overgrowth Mesenteric ischaemia Radiation enteritis? Other Lymphoma Factitious diarrhoea Giardiasis Surgical causes (e.g. small bowel Pancreatic resections) Chronic pancreatitis Autonomic neuropathy Pancreatic carcinoma Drugs Cystic