The lack of effect of phototherapy on serum bilirubin-binding capacity in newborn infants.

Using a Sephadex G-25 separation technique, the total bilirubin-binding capacity was measured in 18 jaundiced infants before and after phototherapy. The initial total bilirubin-binding capacity obtained at 20 to 113 hours of age averaged 17.5 +/- 4.4 mg/dl (mean +/- SD) and was unchanged during phototherapy at 34 to 135 hours of age. In ten infants, the total bilirubin-binding capacity was measured before, during, and 24 hours after the cessation of phototherapy. Here too, phototherapy did not significantly influence the TBBC. These data indicate that in vivo, phototherapy does not alter the serum bilirubin binding capacity of newborn infants.