What is the normal ratio of transaminases?

Under normal circumstances, the aspartate aminotransferase to alanine aminotransferase ratio (AST/ALT ratio) ranges between 0.8 and 1.5. Some sources cite a range of 1.5–2.5:1, but the primary reference standard remains 0.8–1.5. If abnormalities are detected, prompt medical evaluation is recommended. Detailed analysis is as follows:

When the ratio is below 0.8, it may be associated with early-stage acute viral hepatitis, cirrhosis, or alcoholic liver disease. In early acute hepatitis, mild hepatocellular injury leads to faster release of alanine aminotransferase (ALT) into the bloodstream, resulting in a lower ratio. In patients with cirrhosis, widespread hepatocyte necrosis increases the relative release of aspartate aminotransferase (AST), potentially causing ratio inversion. In alcoholic liver disease, direct mitochondrial damage by alcohol results in more pronounced elevation of AST, often leading to a ratio exceeding 2.

If the ratio is above 1.5, it may indicate severe hepatocellular damage or non-hepatic conditions. In active chronic hepatitis, the ratio typically ranges from 1 to 1.5; however, during extensive hepatocyte necrosis, large amounts of mitochondrial AST are released, possibly causing a temporary rise in the ratio. In patients with myocardial infarction or myocarditis, cardiac cell injury leads to increased AST levels, which may result in a ratio below 0.8.

When an abnormal AST/ALT ratio is identified, it should be interpreted in conjunction with other liver function tests. It is advisable to avoid high-fat diets and sleep deprivation, minimize unnecessary medication use, and undergo regular follow-up liver function testing.