Serum alanine aminotransferase levels and prevalence of hepatitis A, B, and delta in outpatients.

We investigated the relationship between alanine aminotransferase (ALT) levels and the prevalence of serologic markers of hepatitis A, hepatitis B, and delta hepatitis in an outpatient population. Sera submitted for routine biochemical testing from 4669 patients were grouped according to ALT level (normal and 1 to 2.5, 2.5 to 5.0, and more than five times the upper limit of normal). Serologic evidence of acute hepatitis A or acute or chronic hepatitis B was detected in 6.1% of specimens with elevated ALT levels compared with 1.3% with normal ALT levels. Patients with ALT levels greater than 2.5-fold and fivefold elevated were associated with a 9.3% and a 15.1% prevalence, respectively, of markers of acute or chronic hepatitis. Antibody to delta hepatitis was detected in nine subjects, all of whom also had serologic evidence of chronic hepatitis B. A retrospective chart review of 80 patients with serologic evidence of acute or chronic hepatitis revealed that 51% of cases were previously undiagnosed, most of which were in the low ALT groups. Hepatitis serologic testing may be indicated in outpatients with unexplained elevations of the ALT level.