Determination of serum albumin in neonatal jaundice. The albumin saturation index

Methods for determination of serum albumin were studied with a view to their use in a new laboratory test designed to help in the management of neonatal jaundice. The use of an albumin saturation index, defined as the ratio of serum albumin concentrations determined by the eosin and bromocresol green dye-binding methods is proposed. The eosin method was chosen because although serum albumin concentration is measured with accuracy and precision in non-jaundiced sera, a reduction in apparent serum albumin concentration is found in jaundiced sera due to the method being carried out at pH 7.10 whereby albumin-bilirubin binding remains firm. The bromocresol green method is used in the index as it measures serum albumin quickly, accurately and precisely in both jaundiced and non-jaundiced sera. Determination of serum albumin by the phenol red and hydroxybenzeneazobenzoic acid dye-binding methods was not of value in the index because accuracy in these methods requires use of buffers at acid pH which result in displacement of bilirubin from its albuminbinding sites.