Respiratory hydrogen excretion as a parameter for lactose malabsorption in children.

Respiratory hydrogen excretion was measured during tolerance tests with lactose, glucose plus galactose, and skim milk in 52 children, 4 to 15 years of age. Ten children appeared to be lactose-malabsorbers, as reflected by increased respiratory hydrogen excretion after administration of 2 g lactose per kilogram, maximum 50 g. Skim milk, equivalent to 0.5 g lactose per kilogram was administered to all lactose-malabsorbers. Eight children were tolerant and two children were "intolerant" for this physiological amount of lactose when administered as skim milk. Disaccharidase activities of jejunal biopsies were determined in all 10 children with lactose malabsorption. Lactase activity was deficient in nine children and normal in one child. The increase of blood glucose during the lactose tolerance test did reflect lactose malabsorption less accurately than the respiratory hydrogen excretion.