chronic diarrhoea

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differential diagnosis

factious: laxatives

common: inflammatory bowel disease, coeliac disease, giardiasis, drugs (e.g. proton pump inhibitor)

uncommon; hypolactasia, colonic neoplasms including villous adenomas , thyrotoxicosis

Rare: endocrine tumours(e.g zollinger-Ellison syndrome

clinical features

Features suggesting pathological disorders:1) nocturnal diarrhea,2) unintentional weight loss,3) mouth ulcers

history

gives clue whether the predominant pathology

~colonic: watery stool often with blood and mucus

~small intestinal diarrhea: may have features of steatorrhoea and weight loss

~Exocrine pancreatic insufficiency: steatorrhoea and weigh loss are hall mark of pancreatic insufficiency. patient may describe pain which is epigastric associated with fatty food intolerance

Examinations

General appearance:patients look well or not? history of weight loss(loose clothes etc)

Physical sign of malabsorption: nail changes such as koilonychia, leukonychia. signs in the tounge and mouth of glottis, cheilitis and ulcers, bruising

Abdominal examinations: rectal examintions, sigmoidoscopy

investigations

1) blood test 2) stool microscopy and culture 3) faecal elastase or faecal chymotrypsin 4)abdominal x-ray 5) endoscopy, duodenal aspirations, biopsy 6) colonoscopy and biopsies 7) hydrogen breath tests 8) small bowel imaging 9) 24 h stool weights 10) fasting gut hormones

Most infectious form resolve within 2-3 weeks. Diarrhoea that last LONGER than this needs to WARRANT.

in outpatient, it is important to distinguish diarrhoea from RECTAL FREQUENCY. (number of defecations per day is increased in the absence of an increase in stool weight

zollinger-ellison syndrome results from gastrin-secreting tumour)

in difficult cases it is IMPORTANT to DISTINGUISH btwn true diarrhea(by stool weights) and not a functional disorder

colonic diarrhea may be associated with urgency defecation

Steatorrhoea: pale, bulky stools that are difficult to wash away

epigastric: pain radiating through to the back

1) blood test= FBC, erythrocyte sedementation rate and biochem for serum albumin, vitamin b12 and folate, thyroid function, tissue transglutaminase antibody for coeliac disease

2) stool microscopy and culture=negative cultures do not exclude giardiasis

3)faecal elastase or faecal chymotrypsin =low in pancreatic insufficiency

4)abdominal x-ray= empty and oedematous colon 5) endoscopy,duodenal aspirations, biopsy = to exclude coeliac disease and giardiasis

6) colonoscopy and biopsies = may reveal microscopic colitis (eg. lymphocytic colitis, collagenous colitis) 7) hydrogen breath tests= confirm suspicion of hypolactasia/ small bowel bacterial overgrowth

8)small bowel imaging

9) 24 h stool weights- useful in distinguishing osmotic and secretory diarrhea

10) fasting gut hormones= if hormone secreting tumour is suspected . if gastrin levels are measured proton pump inhibitors must be stopped

chronic diarrhoea

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