Determination of the upper limits of normal serum alanine aminotransferase (ALT) level in healthy Turkish population.

Recent studies have reported that the widely accepted range of upper limits of normal (ULN) alanine aminotransferase (ALT) levels (ULN<40U/L) is high for the healthy population. We aimed to find the correct ULN level for men and women in a presumed healthy liver population group. The data of 7410 healthy subjects visiting the check-up clinics were retrospectively analysed in this study. Patients were divided in to "healthy liver group" (n=2694) and "high-risk liver group" (n=4716) based on fatty liver on ultrasound, existing of chronic liver disease, ongoing significant alcohol consumption, diabetes mellitus and dyslipidaemia. Receiver operating characteristic (ROC) curves were generated and the area under the curve (AUC) was calculated at the 95th percentiles for both men and women. The AUC score of ALT for men was 0.92, and the ULN for the serum ALT in men was found as 32.10 U/L (sensitivity of 0.89, specificity 0.85). The AUC score of ALT for women was 0.90, and the ULN for serum ALT was found as 23.15 U/L (sensitivity of 0.90, the specificity of 0.88). ULN for serum ALT level should be lowered and different cut-off values should be used for men (32.10 U/L) and women (23.15 U/L).