Improved screening for intestinal villous atrophy by D-xylose breath test

The hydrogen breath test (H2BT) with D-xylose has proven valid in both early recognition and follow-up of intestinal malabsorption. To further evaluate the specificity of the H2BT with D-xylose in the diagnosis of intestinal malabsorption as compared to the conventional urinary D-xylose test, we analyzed the result in 49 patients referred to our unit with a clinical diagnosis of intestinal malabsorption. These patients had an abnormal 25-g D-xylose H2BT but a normal conventional urinary D-xylose test. Jejunal biopsy with Watson capsule was performed in all patients. H&E staining was prepared from each biopsy specimen, and histological changes were classified according to the Marsh criteria. Jejunal biopsy showed mucosal atrophy in 5 patients (10%), hyperplastic lesion in 11 (22.5%), infiltrative lesion in 14 (28.5%), and normal appearance in 19 (39%). G. lamblia infection was additionally diagnosed in two patients. Histological changes were independent of the presence of diarrhea, weight loss, abdominal pain, or anemia. H2 excretion, assessed as increase over baseline and area under the curve, was similarly independent of the histological pattern. In conclusion, performance of a D-xylose H2BT in patients with a normal urinary test reveals a significant number of patients with intestinal mucosal atrophy who might otherwise remain undiagnosed.