AST/ALT ratio (De Ritis ratio)

The AST/ALT ratio, also called the De Ritis ratio after Fernando De Ritis who first described its diagnostic utility in the 1950s, is calculated as aspartate aminotransferase (AST) divided by alanine aminotransferase (ALT). In hepatocellular injury, ALT tends to rise more than AST because it is more liver-specific, yielding a ratio below 1.0; in alcoholic liver disease the ratio typically exceeds 2.0, partly because alcohol-related mitochondrial damage preferentially depletes intracellular pyridoxal phosphate needed for ALT synthesis and because AST release from damaged mitochondria predominates. A ratio above 1.0 in the setting of elevated transaminases also raises suspicion for cirrhosis, where regenerative nodules lose cytosolic ALT preferentially. Beyond liver disease, an elevated AST/ALT ratio in individuals with normal or near-normal absolute enzyme values may reflect non-hepatic AST contributions from skeletal or cardiac muscle. In population-level longevity research, a ratio persistently above ~1.0 in the absence of acute illness or vigorous exercise is associated with higher cardiometabolic risk and all-cause mortality, and should prompt investigation for alcoholic liver injury, steatohepatitis, or underlying cirrhosis rather than being dismissed as unremarkable.