Value and limitations of bilirubin binding capacity in predicting the development of kernicterus.

The serum bilirubin (SBR) and the bilirubin binding capacity (BBC) were determined on hospital admission in 181 consecutive neonates with neonatal jaundice. Twenty-three babies were less than 2500 g and two were of birth weight less than 2000 g. Fifteen babies were preterm. There were eight cases of kernicterus. Although the serum bilirubin was generally higher in infants with a BBC less than 34 mumol/l, there was no correlation between the bilirubin binding capacity and the presence of kernicterus (r = 0.28, P greater than 0.05). However, when both the serum bilirubin and the bilirubin binding capacity were used, a low value of BBC less than 34 mumol/l increased the risk of kernicterus. Higher values of BBC, on the other hand, did not mean that there was less risk of kernicterus, other factors being equal. This, while the bilirubin binding capacity may provide an additional source of information, its limitations should always be borne in mind.