SIMULTANEOUS STUDIES OF UNBOUND BILIRUBIN AND BILIRUBIN BINDING MEASUREMENTS USING TWO (2)AUTOMATED MICROMETHODS

Abstract

Use of 2 automated instruments,the UB Analyzer (Nakamura) and the AVIV Hematofluorometer has allowed us to examine unbound bilirubin values and bilirubin binding measurements simultaneously in 79 infants (142 samples).The UB Analyzer employs a modified peroxidase micromethod to measure unbound bilirubin (UB); results compare well with the manual peroxidase method(r=0.87, p=0.001).The AVIV Hematofluorometer depends on the fluorescence of albumin bound bilirubin.Bound bilirubin(B),total blood bilirubin(T) and reserve binding (R) are measured,as is B/R, (the degree of saturation of albumin binding sites).T-B can be calculated and represents bilirubin in blood not bound at the primary albumin binding site.Simultaneous performance of these measurements was possible in very LBW Infants since each method required 100μl blood.UB correlated directly with TB in all birthweight groups (r=0.69,p=.0001,n=142)and was markedly increased in infants of BW≤1000 g compared with those>1000 g at given bilirubin levels.UB correlated best with B/R(r=0.82,p=.0001,n=142) in all birthweight groups.The relationship between UB & T-B varied with BW and became striking in infants <1000 g (r=0.95,p=0.0001, n-19).Comparison of measures of albumin binding with that of UB has been limited.New insights have been gained by the ability to study these interrelationships in LBW Infants using two simple automated micromethods.