Biology of Bilirubin Photoisomers.
Hansen Thor Willy Ruud
Clinics in perinatology
Phototherapy is the main treatment for neonatal hyperbilirubinemia. In acute treatment of extreme hyperbilirubinemia, intensive phototherapy may have a role in 'detoxifying' the bilirubin molecule to more polar photoisomers, which should be less prone to crossing the blood-brain barrier, providing a 'brain-sparing' effect. This article reviews the biology of bilirubin isomers. Although there is evidence supporting the lower toxicity of bilirubin photoisomers, there are studies showing the opposite. There are methodologic weaknesses in most studies and better-designed experiments are needed. In an infant acutely threatened by bilirubin-induced brain damage, intensified phototherapy should be used expediently and aggressively.
10.1016/j.clp.2016.01.011
Bilirubin binding in jaundiced newborns: from bench to bedside?
Ahlfors Charles E,Bhutani Vinod K,Wong Ronald J,Stevenson David K
Pediatric research
BACKGROUND:Bilirubin-induced neurologic dysfunction (BIND) is a spectrum of preventable neurological sequelae in jaundiced newborns. Current total plasma bilirubin (B) concentration thresholds for phototherapy and/or exchange transfusion poorly predict BIND. METHODS:The unbound (free) bilirubin (B) measured at these B thresholds provides additional information about the risk for BIND. B can be readily adapted to clinical use by determining B population parameters at current B thresholds. These parameters can be established using a plasma bilirubin binding panel (BBP) consisting of B, B, and two empiric constants, the maximum B (B) and the corresponding equilibrium association bilirubin constant (K). RESULTS:B and K provide the variables needed to accurately estimate B at B < B to obtain B at threshold B in patient samples. Once B population parameters are known, the BBP in a newborn can be used to identify poor bilirubin binding (higher B at the threshold B compared with the population) and increased risk of BIND. CONCLUSION:The BBP can also be used in jaundice screening to better identify the actual B at which intervention would be prudent. The BBP is used with current B thresholds to better identify the risk of BIND and whether and when to intervene.
10.1038/s41390-018-0010-3