INFLUENCE OF PHOTOISOMERS IN BILIRUBIN DETERMINATIONS ON KODAK-EKTACHEM AND HITACHI ANALYZERS IN NEONATAL SPECIMENS - STUDY OF THE CONTRIBUTION OF STRUCTURAL AND CONFIGURATIONAL ISOMERS
Jm. Gulian et al., INFLUENCE OF PHOTOISOMERS IN BILIRUBIN DETERMINATIONS ON KODAK-EKTACHEM AND HITACHI ANALYZERS IN NEONATAL SPECIMENS - STUDY OF THE CONTRIBUTION OF STRUCTURAL AND CONFIGURATIONAL ISOMERS, European journal of clinical chemistry and clinical biochemistry, 33(8), 1995, pp. 503-512
We compared data obtained with the Kodak Ektachem and Hitachi 717 Anal
ysers and HPLC from 83 neonates cinder phototherapy. Total bilirubin v
alues determined with the Kodak and Hitachi are in good agreement, but
we observed a large discrepancy in the results for conjugated (Kodak)
and direct (Hitachi) bilirubin. HPLC revealed that all the samples co
ntained configurational isomers, while only 7.7% and 30.8% contained c
onjugated bilirubin and structural isomers, respectively. We developed
a device for the specific and quantitative production of configuratio
nal or structural isomers, by irradiation with blue or green light. In
vitro, total bilirubin values are coherent for the routine analysers
in the presence of configurational or structural isomers. With configu
rational isomers, unconjugated biliribin (Kodak) is lower than total b
ilirubin (Kodak), and conjugated bilirubin (Kodak) is always equal to
zero, so the apparatus gives a false positive response for delta bilir
ubin. In contrast, the direct bilirubin (Hitachi) is constant. Further
more, in the presence of structural isomers, unconjugated bilirubin (K
odak) is unexpectedly higher than total bilirubin (Kodak), conjugated
bilirubin (Kodak) is proportional to the quantity of these isomers, an
d direct bilirubin (Hitachi) is constant. The contribution of photoiso
mers in bilirubin measurements is discussed.