Unwanted Side Effects and Optimization of Phototherapy

Abstract

Phototherapy of hyperbilirubinemia in newborns is a relatively new modality which is mainly based on empirical observations of the beneficial effects of light upon icteric children (Cremer et. al., 1958). Bilirubin is poorly water soluble, and the development of icterus in newborns is caused by a defect in the conjugation mechanism that converts bilirubin to a more water-soluble form that can be excreted. Light irradiation converts bilirubin to other types of water soluble products. The nature of these products and their excretion route have been a matter of discussion during the last years (McDonagh, 1971; McDonagh et al., 1980; Pratesi, 1983). The current view is that light converts bilirubin to photoisomers that can be excreted through the bile or the urine. A number of photoproducts are formed simultaneously. The photoreactions may be complicated and sensitive to a number of factors as light intensity and wavelength (Ennever, 1986).