Galactose absorption after oral administration of lactose in neonates.

1. A lactose tolerance test was performed in infants and children. The majority of the infants showed a good response with serum glucose elevations, while there were poor responders among children more than 2 years old. During this test, serum galactose usually was nondetectable, even in the good responders. 2. After simultaneous loading with a constant amount of galactose and varying amounts of glucose in neonates, the degree of elevation of serum galactose levels decreased with increasing amounts of glucose, and loading with equal amounts of galactose and glucose resulted in no elevation of serum galactose levels. 3. In a 6-year-old galactosemic child, serum galactose levels were markedly and continuously elevated after lactose loading. 4. After galactose loading with simultaneous intravenous glucose loading in neonates, elevation of serum galactose was markedly suppressed, as compared with that after galactose loading alone, while it was higher than that after oral loading with the equal doses of galactose and glucose. From the above, the fact that no increase was observed in serum galactose concentration when lactose was loaded orally in neonates is ascribable partially to inhibited absorption of galactose by glucose in the intestine but in the most part to accelerated metabolism of galactose by the glucose absorbed.