Clinical applicability of shortened D-xylose breath test for diagnosis of intestinal malabsorption.

Urinary and/or plasmatic D-xylose tests are broadly used in clinical practice for the diagnosis of intestinal malabsorption. A 5-hr hydrogen breath test (H2 BT) has also proven useful. Our goal was to determine whether a shorter, hence more efficient, 3-hr test would perform as well as the 5-hr test. We studied 33 patients with proven malabsorption, 44 patients with irritable bowel syndrome (IBS), and 27 healthy subjects. Each individual ingested 25 g of D-xylose, and alveolar breath samples were obtained thereafter at 30 min intervals for 5 hr. Breath samples were analyzed for H2 by gas chromatography. Individual peak delta changes and area under the curve (AUC) were calculated. Simultaneously, the 5-hr cumulative urinary excretion of D-xylose was measured by colorimetry. Results of 5-hr tests were compared with those of the first 3 hrs. In the malabsorption group, the 5-hr test showed a markedly enhanced production of H2 relative to healthy controls (delta: 60.7 +/- 6.4 vs 7.7 +/- 1.5 and AUC: 8465.0 +/- 985.4 vs 393.2 +/- 232.6, P < 0.001). Results in IBS patients did not differ from those in healthy controls. Three-hour analysis also reflected an enhanced production of H2 in the malabsorption group (delta: 45.4 +/- 6.4 and AUC: 3700.0 +/- 545.6, P < 0.001 vs healthy controls).(ABSTRACT TRUNCATED AT 250 WORDS)