Breath hydrogen test in children with giardiasis.

Respiratory hydrogen excretion was measured in 50 children with giardiasis in order to study lactose absorption. Samples of expired air were collected before and after the children drank 250 ml of whole cow's milk. The test was repeated after successful elimination of Giardia lamblia following treatment with tinidazol. The number of children showing a rise in breath hydrogen excretion greater than 20 ppm decreased from 33 (72%) before treatment to 20 (44%) after treatment. This study permits the conclusion that the presence of G. lamblia in the intestine might interfere with optimum lactose absorption.