Serum alanine transaminase (ALT) reference ranges estimated from blood donors

It has been suggested that an increase in serum alanine transaminase (ALT) activity in blood donors may identify infection with non-A, non-B hepatitis. To facilitate identification of such donors, the reference range for ALT was measured on a Technicon SMAC 1 Analyser, using serum from 364 blood donors and 567 plasmapheresis donors. The distribution of ALT activities displayed a positive skewness, and so both logarithmic transformation and subsequent calculation of mean and standard deviation as well as non-parametric analysis were used to obtain best estimates of reference ranges for men and women, 5-65 IU/1 and 5-35 IU/1, respectively. ALT activities were found to be higher in plasmapheresis donors than in normal blood donors of both sexes, and it is postulated that this difference may be related to the increased frequency of donation in the former group.