Evaluation of chronic secretory diarrhea
Because there are many causes of chronic secretory diarrhea, an extensive evaluation is necessary. Rare cases of infection should be excluded by bacterial culture and examination of stool for parasites or tests for protozoal antigens. Stimulant laxative abuse is best excluded by looking for laxatives in the urine or stool. Structural disease and internal fistulas can be evaluated with small bowel radiography or computed tomography (CT) scanning of the abdomen and pelvis. Endoscopic examination of the upper gastrointestinal tract and colon is routine and should include biopsy of even normal-appearing mucosa, looking for microscopic evidence of disease. Systemic diseases such as hyperthyroidism, adrenal insufficiency, and defective immunity can be evaluated with appropriate tests.