All issues > Volume 33(10); 1990

Original Article

J Korean Pediatr Soc. 1990;33(10):1319-1325. Published online October 31, 1990.

The Effect of Phototherapy on Serum bilirubin Binding Capacity and Affinity in the Neonate.

In Suck Ryu¹, Chul Lee¹, Ran Namkung¹, Dong Gwan Han¹

¹Department of Pediatrics, Yonsei University, College of Medicine Seoul, Korea

Received: April 20, 1990;  Accepted: June 17, 1990.

Abstract

Since the effect of phototherapy in the treatment of neonatal hyperbilirubinemia has been reported 30 years ago, phototherapy has been used widely for neonatal hyperbilirubinemia, but the exact mechanism and the effect of light on the human body have not been fully determined. Free bilirubin level in the serum is an important indicator for kemicterus, a complication of neonatal hyperbilirubinemia. Free bilirubin level was determined by the affinity and binding capacity of bilirubin to serum albumin. Light-induced changes in the albumin molecule, or competitive binding of a phototherapy break- down product to albumin, could decrease the binding capacity and affinity of serum albumin to bilirubin and render such therapy self-defeating. 20 infants bom in Yongdong Severance Hospital who were treated for physiologic jaundice during the period between October 1988 and February 1989 were entered in the study. Serum free bilirubin concentration was determined by automated peroxidase micromethod. Each serum was titrated for the determination of bilirubin binding capacity and affinity by serial additions of small aliquots of bilirubin to the serum. Scatchard plot was used to estimate the binding capacity and affinty of bilirubin to albumin. The level of bilirubin in sera of pre and post phototherapy were 12.9 ±1.80 mg/dl and 8.30 ±1.99 mg/ dl respectively. There was no significant difference between albumin biniding capacity to bilirubin before (25.846 ± 3.069 mg/dl) and after (26.613 ±2.655 mg/dl) therapy. The molar ratio of bilirubin and albumin before and after treatment showed no significant difference (0.792±0.093 and 0.752±0.115 respectively). Albumin binding affinity to bilirubin before (13.102 x 107/M) and after treatment (14.647 x 107/M) showed no significant difference. We concluded that phototherapy for 48 hours has no influence on albumin-bilirubin binding capacity and affinity.

Keywords :Bilirubin, Phototherapy