SLOW EXCRETION OF THE 4Z-15E-BILIRUBIN CONFIGURATIONAL ISOMER DURIN PHOTOTHERAPY FOR CRIGLER NAJJAR SYNDROME

Phototherapy (PT) is the only treatment of value in the long-term management of Crigler–Najjar syndrome type I (C-N.s.). At present (Proc.Natl.Acad.Sci.USA 78:1882, (1981)) it seems that the formation and elimination of the 4Z,15E-bilirubin configurational isomer (Z,E) is the major contributor in lowering bilirubin (BR) levels during PT for C-N.S.. TO verify this hypotesis, we have analyzed the serum BR isomer composition of a 15-years-old girl with C-N.s. during PT by HPLC method. We used green (Sylvania F20T12/G) and ‘special’ blue (Philips F20T12/BB) fluorescent lamps because of their different capacity to produce Z,E isomer. We report the steady-state serum concentrations of Z,E with either green and ‘special’ blue PT. The excretory rate for the Z,E isomer was estimated by measuring the Z,E concentration at the cessation of PT and after 2 hours (patient kept under red light). Our result show that during the 2 hours period following the interruption of both green and ‘special’ blue PT the absolute serum amount of Z,E remains nearly constant. Moreover, before the beginning of PT, the patient had a significant serum level of the Z,E isomer (13.2% ± .2%) due to the blue light PT administered 12 hours before. These evidences show that in this patient the disappearance rate of Z,E isomer is too slow to account for the total BR excretion during PT.