Diagnostic Approaches for Malabsorption

Initial Assessment

Confirmation of true diarrhoea through stool inspection and measurement of stool weight is recommended before pursuing extensive malabsorption workup, as recommended by the European Society of Gastroenterology 1
Initial laboratory investigations should include full blood count, erythrocyte sedimentation rate, electrolytes, liver function tests, iron studies, vitamin B12, folate, and thyroid function, according to the European Society of Gastroenterology 1

The European Society of Gastroenterology recommends antiendomysium antibody testing as the preferred first-line test for coeliac disease, the most common small bowel enteropathy in European populations 1, 2
If small bowel malabsorption is suspected and serological tests are negative, the European Society of Gastroenterology suggests upper gastrointestinal endoscopy with distal duodenal biopsies should be performed 2
For suspected pancreatic insufficiency, the European Society of Gastroenterology prefers newer specific tests such as stool elastase over older methods 3

The European Society of Gastroenterology discourages the use of quantification of three-day faecal fat due to its poor reproducibility, unpleasantness, and non-diagnostic value 3
Breath tests for fat malabsorption (using 14C-triolein or 13C-labeled mixed triglyceride) have low sensitivity for mild/moderate fat malabsorption but may serve as alternatives to faecal fat collection where available, as suggested by the European Society of Gastroenterology 3

Carbohydrate malabsorption is predominantly associated with mucosal disease or dysfunction, according to the European Society of Gastroenterology 4
Hydrogen breath tests offer better diagnostic value for specific carbohydrate intolerances than stool pH or reducing substances, as recommended by the European Society of Gastroenterology 1