What is AST / ALT Ratio?
The AST/ALT ratio — also called the De Ritis ratio — is the relationship between two liver enzymes with slightly different tissue profiles. AST is present in both liver and muscle (and heart tissue), while ALT is more selective for liver tissue. The ratio is therefore a supporting tool to help distinguish whether a rise in liver enzymes is primarily of liver origin or partly explained by muscle. The ratio is only meaningful when AST or ALT are abnormal — with both enzymes sitting comfortably within normal ranges, the ratio carries no information. It is also a tool, not a diagnosis: absolute values, GGT, bilirubin, ALP, and clinical context remain primary when interpreting liver enzymes.
Why is AST / ALT Ratio relevant?
Classically, an AST/ALT ratio below 1 is associated with non-alcoholic liver conditions and lifestyle-related liver stress, while a ratio above 2 has traditionally been linked to alcoholic liver disease. In practice, the line is blurrier than once thought: recent intensive training, muscle injury, and certain myopathies can push AST up strongly and take the ratio above 1 without any liver involvement. For the ratio to be useful, it is always layered onto the broader liver enzyme pattern. A ratio above 2 with markedly elevated absolute AST and ALT values, alongside raised GGT, in someone who drinks regularly, carries more weight toward suspected alcoholic liver disease than the same ratio alone in someone who ran a marathon the day before.
AST / ALT Ratio high or low — what it means
Assess the ratio only when AST or ALT are outside the reference range. Check first whether recent training, muscle injury, or muscle disease might be artificially lifting AST — in that case the ratio says little about the liver. GGT is a useful additional marker: with a liver origin GGT tends to rise with the enzymes; with a purely muscle origin it stays near normal. The ratio is not a substitute for the full liver enzyme profile. Use it as one piece alongside ALT, GGT, bilirubin, ALP, and the clinical story. A ratio that repeatedly exceeds 2 with elevated liver enzymes — especially combined with other liver markers — warrants clinical attention and possibly imaging or additional blood tests.
Educational information only — not medical advice. Consult a healthcare professional for clinical decisions.
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