Diagnosing lactase deficiency in three breaths.
BACKGROUND
Lactose hydrogen breath tests (H(2)-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.


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


METHODS
Lactose H(2)-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 H(2)-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.


CONCLUSIONS
A three-sample breath test (baseline, 60/90 min and 120 min) has excellent sensitivity and specificity for lactase deficiency. Lactose H(2)-BT can be simplified but not shortened to <2 h.
Department of Internal Medicine, Stadtspital Triemli, Zurich, Switzerland.
M
M
Oberacher
D
D
Pohl
S R
SR
Vavricka
M
M
Fried
R
R
Tutuian
D001944:Breath Tests / Q000379:methods*; D006801:Humans; D043322:Lactase / Q000172:deficiency*; D007787:Lactose Intolerance / Q000175:diagnosis* / Q000209:etiology; D012680:Sensitivity and Specificity
D043322:Lactase