COMPARISON OF A PORTABLE BREATH HYDROGEN ANALYZER (MICRO H-2) WITH A QUINTRON MICROLYZER IN MEASURING LACTOSE MALDIGESTION, AND THE EVALUATION OF A MICRO H-2 FOR DIAGNOSING HYPOLACTASIA

The measurement of hydrogen in exhaled air and changes in the concentr ation of blood glucose and urine galactose excretion are indirect meth ods of diagnosing hypolactasia. The aim of this study was to compare a portable breath hydrogen analyser (Micro H-2) with a widely used mode l (Quintron MicroLyzer) and to compare them with the blood glucose, ur ine galactose, and gastrointestinal symptoms in the lactose tolerance test. After an overnight fast, 44 volunteers (18-66 y) ingested 50 g l actose in a single oral dose. Changes in exhaled breath hydrogen conce ntrations were measured with the two analysers, and changes in blood g lucose and urinary galactose were assayed for 4 h and used as a refere nce. Eighteen subjects were diagnosed as maldigesters according to our gold standard of at least two positive tests out of the three: breath hydrogen by Quintron, blood glucose concentration, and urine galactos e excretion. The highest increase in the breath hydrogen concentration over the baseline was highly variable: 44-366 ppm (Micro H-2) or 27-1 87 ppm (Quintron MicroLyzer). The sensitivity, specificity, and positi ve and negative predictive values of the Micro H-2 compared to the gol d standard were 83%, 96%, 94% and 89%, respectively. Overall agreement was 91% (95% CI 78-97%). Compared to the Quintron, the diagnoses were identical in 100% of the cases (92-100%). Thus, for diagnosing hypola ctasia, the Micro H-2 appeared as reliable for measuring breath hydrog en concentrations as Quintron MicroLyzer commonly used in oral lactose tolerance tests.