Evaluation of diagnostic examinations of lactose intolerance in children

Introduction: The diagnosis of lactose intolerance is established on the basis of the clinical picture, the hydrogen breath test and/or determined concentration of glucose in the blood after the oral lactose load. The most valuable examination seems to be the determination of lactase activity in the intestinal biopsy. However, in the literature there are only a few studies comparing these diagnostic methods.
Aim: To evaluate the sensitivity and specificity of the hydrogen breath test and the evaluation of glucose concentration in the blood after lactose load in comparison with lactase activity in the intestinal biopsy.
Material and methods: In 61 children we performed the hydrogen breath test and the oral lactose load test with determination of glucose concentration in the blood, and we determined lactase activity in the intestinal biopsy.
Results: In 79% of the patients we observed compatibility between the hydrogen breath test and lactase activity, in 16.6% the hydrogen breath test gave false positive results, and in 4.4% the results were false negative. In a majority of the patients with false positive results of the hydrogen breath test, lactase levels were in the low normal range. The oral lactose load test with the determination of glucose concentration in the blood was characterized by lower sensitivity and specificity. In over 20% it showed false positive results and in 10% false negative results.
Conclusions: With regard to the large number of false positive and negative results in the hydrogen breath test and the oral lactose load test with the determination of glucose concentration in the blood, in the case of diagnostic difficulties it seems reasonable to determine lactase activity in the intestinal biopsy.