Serum Levels of Alanine Aminotransferase Decrease With Age in Longitudinal Analysis

BACKGROUND & AIMS: An increased level of alanine aminotransferase (ALT) is a marker of liver injury. The mean ALT level has been reported to decrease with age; we performed a longitudinal analysis to determine whether serum levels of ALT changes with age among community-dwelling, older adults in the US. METHODS: We analyzed clinical data from 2 cohorts of individuals who participated in the Rancho Bernardo Study, in Southern CA. The first cohort comprised 1073 community-dwelling participants (59% women); clinical data was collected from 1984-1987 and 1992-1997. The second cohort comprised 416 participants (64% women); data was collected from 1984-1987, 1992-1997, and 1997-1999. Demographic, metabolic covariates, ALT, bilirubin, and albumin were measured. Changes in individual ALT over time were examined in unadjusted and multivariable-adjusted linear and logistic regression analyses. RESULTS: At the baseline visit, the patients' mean age was 65.7 years and body mass index was 24.9 kg/m(2). In cohort 1, the mean levels of ALT decreased with age by 10% (from 21 to 19 IU/L) between the time periods of 1984-1987 and 1992-1997 (P < .0001). In cohort 2, they decreased by 20% (from 20 to 16 IU/L) between the time periods of 1984-1987 and 1997-1999 (P < .0001). Categorically-defined increases in ALT also decreased with age (P < .0001). Results remained consistent in sex-specific analyses and after adjusting for metabolic syndrome components, alcohol use, bilirubin, and serum levels of albumin (P < .0001). CONCLUSIONS: In a longitudinal analysis, we observed that levels of ALT decrease with age, independent of sex, metabolic factors, alcohol use, and results from commonly used liver function tests (bilirubin and albumin). When interpreting serum levels of ALT, physicians should consider patients' age especially in the elderly.