Influence of gender on the ratio of serum aspartate aminotransferase (AST) to alanine aminotransferase (ALT) in patients with and without hyperbilirubinemia.

The serum asparate aminotransferase (AST)/alanine aminotransferase (ALT) ratio is widely used in the differential diagnosis of icteric and non-icteric hepatic disorders. Our objective was to determine whether there are gender related-differences in the serum AST/ALT ratio. We used sera from 3,618 unselected patients sent to our laboratory for an automated chemistry panel, which included measurements of AST, ALT, alkaline phosphatase, and total bilirubin. Effects of gender on serum AST, ALT, and AST/ALT were examined in different age groups. Among patients with normal total serum bilirubin concentrations, serum AST and ALT concentrations were significantly lower in the females than in the males (P < 0.0001). However, the serum AST/ALT ratio was higher in the females than the males (median values of 0.90 and 0.81, respectively; P < 0.0001). AST and ALT were also lower in the 54 hyperbilirubinemic females than in the 102 hyperbilirubinemic males. Serum AST/ALT ratios were considerably higher in these 156 hyperbilirubinemic patients than in the normobilirubinemic group, with median ratios of 1.09 in females and 0.92 in males (P = 0.02). Significantly higher serum AST/ALT ratios in females were first evident in the 3rd age decade and remained significantly higher than ratios in males through the 8th decade. We conclude that serum AST/ALT ratios are higher in women than men. When clinicians utilize serum AST/ALT ratios to assess the etiology or chronicity of liver disease, the patient's gender also should be taken into consideration.