AST/ALT Ratio (De Ritis Ratio)

The AST/ALT ratio, classically known as the De Ritis ratio, is a readily accessible biochemical index used clinically to assist in the differential diagnosis and evaluation of liver disease. Calculated by dividing the serum level of aspartate aminotransferase (AST) by alanine aminotransferase (ALT), this metric leverages the distinct intracellular distributions and half-lives of these transaminases to provide etiological clues regarding hepatocellular injury.

The interpretation relies on established clinical thresholds: a ratio of less than 1.0 is typically observed in acute viral hepatitis, non-alcoholic fatty liver disease (NAFLD), and extrahepatic cholestasis, driven by a predominant ALT elevation. Conversely, as liver disease progresses to advanced fibrosis and cirrhosis, the ratio frequently inverts, making values between 1.0 and 2.0 indicative of progressive chronic liver disease.

Furthermore, a ratio greater than 2.0 is strongly suggestive of alcoholic liver disease, particularly when the absolute AST level remains below 300 U/L. This index serves as a crucial, non-invasive initial triage parameter that helps clinicians guide further diagnostic workup and formulate targeted management strategies.