Serum alanine aminotransferase in blood donors: activity distribution and effect of phenotype.

Alanine aminotransferase (ALT) phenotype and serum activities were determined in 200 random volunteer blood donors. Serum enzyme activities were not significantly affected by the ALT phenotype (p greater than 0.1). Studies on 500 random volunteer blood donors showed significant differences in serum ALT levels between male and female donors (p less than 0.001). Elevated serum ALT levels were more commonly found in male donors; the frequency of male donors with levels of 45 IU/l or higher was 2.5 percent compared with 0.9 percent in female donors. The frequency of donors with serum ALT levels of 80 IU/l or higher was 0.6 percent of the total donor population sampled.