Small intestine transit time and lactose absorption during phototherapy.

Diarrhea is often seen during phototherapy in jaundiced infants. Lactose malabsorption and reduced gut transit time (GTT) are some of the proposed explanations. However, the etiology of the diarrhea is still controversial. We investigated GTT and lactose absorption during phototherapy using the H2 breath test. Breath H2 was measured every 10 min for 150 min after feeding of jaundiced infants with and without phototherapy, and in controls. There were 12 newborns in each group. The time of increase of H2 excretion over 10 ppm was taken as the transit time. Lactose malabsorption was estimated by integrating the area under the excess H2 curve. No difference was found in GTT, lactose absorption, peak breath H2 and the time of the peak between phototherapy-treated infants and jaundiced and nonjaundiced infants. The results did not support the presence of lactose malabsorption during phototherapy and the decreased total GTT reported in the literature was not due to shortened small intestinal transit time.