Phototherapy-associated diarrhea. The role of bile salts.

The concentration of fecal bile salts was measured in 14 jaundiced neonates who received phototherapy (PT group) and their 14 nontreated matched controls (C). Before initiation of phototherapy, mean bile salt concentrations in stool specimens from the two groups were similar. At 12 hours of 'lights on', stool specimens from PT babies showed a significantly increased mean bile salt concentration, whereas in the C babies there was no change (3.65 +/- 0.39 vs 2.62 +/- 0.22 mmol/l; p less than 0.01). At 24 hours after 'lights off', stool specimens from the PT infants had a mean bile salt concentration like that before phototherapy, and not different from C. During phototherapy, nine PT babies had a bile salt concentration in their stools of 3.5 mmol/l and above; 6 of these babies had watery stools with a high sodium content. The high concentration of bile salts found in the colonic contents of neonates during phototherapy would appear to be a factor in the pathogenesis of phototherapy-associated diarrhea in the jaundiced neonate.