Transcutaneous bilirubinometry. Effect of irradiation on the skin bilirubin index

We studied the relation between irradiation and the percent decrease of skin and serum bilirubin during phototherapy. There was a significant positive correlation between the percent decrease of transcutaneous bilirubinometry readings at the sites exposed directly to light (chest) and irradiation (r = 0.593, p less than 0.001, n = 32). A significant positive correlation was also found between the percent decrease of serum bilirubin concentration and irradiation (r = 0.587, p less than 0.001, n = 32), and the percent decrease of skin bilirubin at exposed sites (chest) and the percent decrease of serum bilirubin concentration (r = 0.481, p less than 0.001, n = 32). Thus, light energy quantitatively affects skin and serum bilirubin. In order to determine the optimal effective wavelength and irradiation energy for phototherapy, it is necessary to examine skin bilirubin kinetics in detail during phototherapy.