What does an elevated AST/ALT ratio indicate?

The aspartate aminotransferase (AST) to alanine aminotransferase (ALT) ratio—commonly referred to as the AST/ALT ratio or “De Ritis ratio”—is a clinically useful hepatic enzyme index. A ratio greater than 1.0 (i.e., AST > ALT) is considered elevated and may signal specific patterns of liver injury or underlying systemic disease.

An elevated AST/ALT ratio is frequently observed in alcoholic liver disease, where AST levels often rise two- to threefold above the upper limit of normal while ALT remains only mildly elevated—resulting in a ratio typically between 2:1 and 3:1. This pattern reflects mitochondrial damage and impaired hepatic pyridoxal phosphate metabolism induced by chronic alcohol exposure.

It may also be seen in advanced chronic liver disease, including cirrhosis of any etiology, due to preferential loss of hepatocyte cytoplasmic ALT relative to more stable mitochondrial AST, as well as reduced hepatic synthetic capacity. In contrast, in most forms of acute viral hepatitis or nonalcoholic fatty liver disease (NAFLD), the ratio is usually <1.0, with ALT markedly exceeding AST.

Importantly, an elevated AST/ALT ratio is not liver-specific. It can occur in non-hepatic conditions such as acute myocardial infarction, rhabdomyolysis, hemolysis, or severe shock—contexts in which AST (which is abundant in cardiac muscle, skeletal muscle, and red blood cells) is disproportionately elevated compared to ALT (which is predominantly hepatic).

Interpretation must always be contextual: clinical history, physical examination, additional liver tests (e.g., alkaline phosphatase, GGT, bilirubin, albumin, INR), imaging, and sometimes liver biopsy are essential to determine the underlying cause. Isolated elevation of the AST/ALT ratio without corroborating evidence should not be used to diagnose liver disease.