Available bilirubin binding sites of serum from newborns determined by a direct spectrometric method using bromphenol blue.

A new direct spectrometric micromethod for the determination of the available bilirubin binding sites of serum (S-ABBS) using bromphenol blue has been applied to 298 blood specimens collected from infants immediately before starting the first exchange transfusion. A relative number fraction of 0.07 of the material, characterized by having the lowest S-ABBS values, includes seven of the nine cases (i.e. a relative number fraction of 0.78) with autoptically verified kernicterus (KI). The two infants with KI but higher S-ABBS values differed in having severe neurological symptoms before the examination. The mean substance concentration of bilirubin in these nine sera was 288 mumol/l. The correlation of KI to the body mass at birth, to the substance concentration of serum albumin, and to the substance concentration of serum bilirubin is given, and the sources of error concerning the method are discussed. The present method is proposed for determining a type of quantity that is important, among other types of data, in deciding on the need for exchange transfusion in icteric (premature) newborns.