Cellobiose: mannitol differential permeability in small bowel disease.

Cellobiose and mannitol absorption were studied in patients with suspected abnormal function of the small bowel mucosa. The urinary cellobiose:mannitol ratio was increased in subtotal villous atrophy, iron deficiency anaemia, and small intestinal Crohn's disease. The test seems a sensitive indicator of the integrity of small bowel mucosa.