Dept. of Operation, Chinese Blood Services Foundation, Taiwan

Alanine aminotransferase (ALT) was widely used as a surrogate marker of infectious hepatitis for voluntary blood donations. But knowledge about overlap between normal and abnormal populations was limited. The highest value of normal donors, 45 IU/L, was arbitrarily estimated to exclude the suspect donations of non-A, non-B and non-C hepatitis. The blood centers usually said that they consistently discarded more than 2.5% donations per year even after the virtuous ELISA tests of HBsAg and anti-HCV have had been applied.

To develop a more appropriate criteria, the complete 1994 database of Kaoshiung blood center of 211,733 donations was analyzed statistically. The study donors were categorized into three groups : first-time 250ml whole blood (WB) donors (28.3%), repeated 250ml WB donors (50.0%) and repeated 500ml WB and/or plateletpheresis donors (21.7%). Their positive rates were 17.9%, 4.6% and 2.7% respectively for at least one positive item in the screening profile consisting of HBsAg, anti-HCV, anti-HIV-1 and Syphilis.

Statistical calculation were conducted on natural logarithmically transformed ALT data. Based on 45 IU/L limit value, the Gaussian distribution excluded 9.7% and 1.1% of those donors of positive screening profile and those totally negative donors respectively. For above-mentioned three categories in the totally negative group, 1.5%, 0.7% and 2.9% abnormal ALT were obtained. In order to fix the exclusion of 1% donations, the criteria could be adjusted to 40 IU/L, 41 IU/L and 58 IU/L separately for these three categories.