Phototherapy for neonatal jaundice--therapeutic effects on more than one level?

Phototherapy for jaundice is a common treatment in neonatal medicine and is used to prevent the neurotoxic effects of bilirubin. Studies have assessed the optimal wavelength of phototherapy light, the importance of irradiance and spectral power, and the types of light source, including the use of single versus multiple light sources. Outcome measures have been duration of need for phototherapy or rate of reduction of serum bilirubin over a given time. An apparent resurgence of kernicterus in recent years has forced us to focus on the emergency management of severely jaundiced infants. Several studies have shown that very rapid reductions of total serum bilirubin levels are possible. The speed with which photoisomers are formed appears to be important both from this perspective and theoretically may also be neuroprotective because of the more polar nature of the photoisomers. This work reviews the evidence concerning the speed of photoisomer formation, as well as the evidence regarding the relative neurotoxicity of bilirubin isomers.