Alanine aminotransferase levels among volunteer blood donors: geographic variation and risk factors.

The incidence of elevated levels of alanine aminotransferase (ALT) in the serum of volunteer blood donors from different geographic areas of the United States was evaluated. Five regional blood collection centers participated by collecting samples randomly from volunteer blood donors. Serum samples were centrally tested for elevated ALT levels, and a sociodemographic questionnaire was sent to donors with elevated ALT levels and to a randomly selected group with normal levels. Significant regional variation was found in the incidence of elevated ALT levels. Age, sex, and the use of alcohol were all significantly associated with elevated ALT levels. These preliminary data are important in the consideration of a program to screen blood donors for elevated ALT levels in serum.