THE HEALTHY RANGE FOR SERUM ALT AND THE CLINICAL SIGNIFICANCE OF "UNHEALTHY" NORMAL ALT LEVELS IN THE KOREAN POPULATION

Abstract

Backgrounds/Purpose: It remains unclear whether the currently used normal range for serum alanine aminotransferase (ALT) levels really reflects a healthy liver. This study was performed to evaluate the healthy range of serum ALT in the Korean adult population and to determine the clinical significance of unhealthy levels.

Methods: We reviewed the medical records,including questionnaires and the results of laboratory and radiologic tests conducted at the Health Promotion Center in Korea University Anam Hospital between March 2005 and February 2007. The records written in questionnaire form included the baseline data, including physical status, social behaviors, medication history, and past and present disease histories.

Results: The mean age of the 7403 enrolled subjects was 48 years, and 49.9% of them were men. A healthy cohort was selected after excluding subjects who showed any abnormalities of the factors that were significantly associated with serum ALT level on multivariate regression analysis. The upper limit of the healthy range of serum ALT level (i.e., 95th percentile) in the healthy population was 31 IU/L for the men and 23 IU/L for the women. The prevalence of metabolic syndrome and insulin resistance were significantly higher in subjects with an“unhealthy” normal ALT level than in subjects with a healthy ALT level.

Conclusions: In our study, the upper limit of the healthy range of serum ALT level was 31 IU/L for the men and 23 IU/L for the women. An unhealthy normal ALT level was associated with higher prevalence of metabolic syndrome and insulin resistance.