The aim of the study was to assess the usefulness of laboratory investigations available in outpatient clinics for the diagnosis of lactose malabsorption in children. The study included 113 children with suspected lactose intolerance (aged 4 months - 15 years). After an oral lactose load, routine lactose tolerance test (LTT) and hydrogen breath test (HBT) with Hoek Loos Lactometer H2- Breath Tester were carried out simultaneously in all the children. 82% of children under 3 year of age scored positive result of LTT, and in 78% of them the increase of H2 in expired air did not exceed 10 ppm. Obtained results suggest that LTT is performed too often in children under 3 years of age, and in the case when clinical picture raises doubts, HBT may eliminate a more invasive LTT. The study was carried out within project ST-60/AMG.

Keywords: Lactose Intolerance, Diagnosis, hydrogen breath test