Diagnosing lactase deficiency in three breaths

Abstract

Background:

Lactose hydrogen breath tests (H₂-BTs) are widely used to diagnose lactase deficiency, the most common cause of lactose intolerance. The main time-consuming part of the test relates to the sampling frequency and number of breath samples.

Aim:

Evaluate sensitivities and specificities of two- and three-sample breath tests compared with standard breath sampling every 15 min.

Methods:

Lactose H₂-BT with probes samples every 15 min served as gold standard. Sensitivity, specificity, positive and negative predictive value of two-sample tests (0–60 min, 0–90 min or 0–120 min) and three-sample tests (0–60–90 min, 0–60–120 min or 0–90–120 min) were calculated.

Results:

Among 1049 lactose H₂-BT performed between July 1999 and December 2005, 337 (32%) had a positive result. Two-sample tests had sensitivity and specificity of 52.5 and 100.0% (0–60 min), 81.9 and 99.7% (0–90 min), and 92.6 and 99.2% (0–120 min), respectively. Three-sample tests had sensitivity and specificity of 83.4 and 99.7% (0–60–90 min), 95.0 and 99.2% (0–60–120 min), and 95.0 and 98.9% (0–90–120 min), respectively.

Conclusion:

A three-sample breath test (baseline, 60/90 min and 120 min) has excellent sensitivity and specificity for lactase deficiency. Lactose H₂-BT can be simplified but not shortened to <2 h.