Fluorometric determination of "albumin-titratable bilirubin" in the jaundiced neonate.

We report a fluorometric technique for determination of albumin-titratable bilirubin in the jaundiced neonate. Although bilirubin alone has very little native fluorescence, considerable emission is observed in the presence of albumin under acid conditions. Analysis of the plasma sample alone and in the presence of excess human serum albumin solution appears to reflect the bilirubin tightly bound to albumin and the total serum bilirubin, respectively. The difference between these two values has been designated as "albumin-titratable bilirubin". Where the concentration of albumin-titratable bilirubin is considerable, a typical saturation effect is observed. In samples where the circulating bilirubin is strongly bound to endogenous alumin, no change in fluorescence is seen when exogenous albumin is added. Results correlate well with the clinical picture.