Human Serum Bilirubin

The technic of Powell (3) for the estimation of serum bilirubin has been modified by reading the optical density of the solutions shortly after mixing the reagents and using a standard based on a more appropriate solution of crystalline bilirubin in pigment-free serum. Seven specimens of bilirubin were examined spectrophotometric-ally; the disproportionality of the millimolar extinction coefficients at 453 mµ for the free-bilirubin and at 532 mµ for, the azobilirubin complex indicated the presence of an unreactive yellow pigment. The destructive effect of sunlight on solutions of biirubin, noted in the literature, was confirmed, hence all estimations were done without delay or exposure to light for any length of time. The results obtained on apparently healthy blood donors, to detect possible carriers of homologous serum hepatitis, revealed no definite correlation between previous history of jaundice and increased serum bilirubin values, but as a precautionary measure individuals with values above 1.5 mg. per 100 ml. were not accepted as donors. When 200 random values were plotted, the distribution curves gave a mean value higher for males than females. Furthermore, 108 donors (among the 25,000 screened) had biirubin values greater than 1.5 mg. per 100 ml. The eleven females of the group did not maintain high values, while 30 males recorded high values on more than one occasion, some consistently. No significant correlation was found between high bilirubin values and a previous history of jaundice, nor were any cases of posttrans-fusion hepatitis traced to these donors. Somewhat arbitrarily, 1.5 mg. per 100 ml. was chosen as the upper limit of normal.