Laboratory Tests and Ancillaries
Irritable Bowel Syndrome_DiagnosticsA routine evaluation should not include diagnostic tests, as testing should be individualized (based on the patient's age, sex, family history of GI disease, predominating symptom, duration and severity of symptoms, presence of stress, other psychological factors, or non-irritable bowel syndrome symptoms, availability, and cost of the test). Lab tests do not increase the diagnostic yield for irritable bowel syndrome, but if necessary, the following tests may be requested: Complete blood count (CBC); erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), fecal calprotectin, fecal lactoferrin (testing for inflammatory markers during first-line investigation avoids invasive procedures [eg colonoscopy or sigmoidoscopy] in excluding inflammatory causes of symptoms [eg IBD]); stool exam (white blood cells, ova, parasites, occult blood), and antibody testing (immunoglobulin A tissue transglutaminase [TTG], endomysial antibodies [EMA]) to rule out celiac disease; thyroid function tests; hydrogen breath test for lactose intolerance and small intestinal bacterial overgrowth; and ferritin, folate and vitamin B12 levels.