Estimation of the Normal Upper Limits for Serum Alanine Aminotransferase in a Population-Based Study from Southeast of Iran

Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) are two accessible indices for liver evaluation. Upper limit of normal (ULN) of these tests are important for starting further investigations for persons with high values. In recent years, cut off points for ULN of these tests have been disputed. This study aimed to determine the ULN of ALT and AST in a population-based study.

This cross-sectional study was performed on a randomized clustered sample of people of Kerman city. Demographic, anthropometric, and laboratory data were collected and analyzed. After excluding the recognized risk factors for liver function tests in another group (group 2), data were analyzed in this subgroup.

Of 2748 subjects included in this study, 1172 (42.4%) were men, with an age range of 15-85 years. The mean (± SE), median, mode, and 95th percentile were 23.74 ± 0.18, 22, 19, and 37 for AST and 22.37 ± 0.27, 18, 15, and 46 for ALT, respectively. The levels of AST and ALT were higher in men and middle age group (P<0.0001). Similar results were obtained for gender but the association of AST and ALT with age was disappeared in another group.

According to the results of the present study, it is recommended to measure the ULN of AST and ALT periodically in different regions concerning age and gender.