REAPPRAISAL OF ALANINE AMINOTRANSFERASE THRESHOLD FOR BLOOD DONORS IN TAIWAN
YANG BS, WANG CS, TU LJ, LIN KS.
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.
Copyright 1997 Hong Kong Medical Technology Association .
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