AST/ALT (De Ritis) Ratio Calculator
A key indicator in the differential diagnosis of liver disease
Last updated on: July 5, 2025
AST/ALT Ratio Calculator
What is the De Ritis Ratio?
The De Ritis ratio is the calculated ratio of two common liver enzymes: Aspartate Aminotransferase (AST) and Alanine Aminotransferase (ALT). Both enzymes are typically elevated in liver damage, but the ratio between them provides important diagnostic clues.
ALT is found primarily in the liver, making it a more specific indicator of liver inflammation. AST is found in the liver as well as in heart, muscle, and other tissues. The relative ratio helps pinpoint the likely cause of the liver injury.
Why is the Ratio Clinically Useful?
- A ratio > 2 is highly suggestive of alcoholic liver disease, as alcohol toxicity depletes pyridoxal phosphate, which is a necessary cofactor for ALT synthesis more than for AST.
- A ratio of ≈1 is often seen in acute viral hepatitis or non-alcoholic steatohepatitis (NASH).
- A ratio < 1 is common in many other forms of chronic liver disease where inflammation is the primary driver.
Interpreting the Result (Reference Guide)
Ratio > 2.0:
Highly suggestive of alcoholic hepatitis or cirrhosis.
Ratio ≈ 1.0:
Commonly seen in acute viral hepatitis or non-alcoholic steatohepatitis (NASH).
Ratio < 1.0:
Often indicates other forms of liver injury, such as chronic viral hepatitis or toxic hepatitis.
Important Considerations
- Extremely high AST and ALT levels (in the thousands) often point towards acute viral hepatitis or ischemic/toxic injury, regardless of the ratio.
- This ratio is most useful when transaminase levels are moderately elevated.
- Always correlate the ratio with patient history, symptoms, and other laboratory findings.
- Consult a gastroenterologist or hepatologist for a definitive diagnosis.
This page has been medically reviewed by Dr. Khoulah Attia – PharmD, Immunology Specialist.