Hepatology
AST to ALT Ratio
The AST/ALT ratio helps differentiate etiologies of liver injury. Enter serum AST and ALT to calculate the ratio and receive guidance on interpretation.
Inputs
- AST: 60
- ALT: 45
AST/ALT ratio
1.33
Common range 0.5–2.5
AST/ALT 1–1.99 can be seen in advanced fibrosis, cirrhosis, or extrahepatic sources of AST (e.g., muscle injury). Interpret with other labs and imaging.
Correlate with GGT, alkaline phosphatase, bilirubin, and imaging to refine diagnosis.
How to Use This Calculator
Collect recent AST and ALT values
Use the same laboratory draw. Ensure the patient avoided strenuous exercise and alcohol immediately before testing.
Enter values to compute the ratio
The tool divides AST by ALT and classifies the result into clinically relevant bands.
Interpret alongside other data
Combine with fibrosis scores (APRI, FIB-4), imaging, viral serologies, and medication review before final diagnosis.
Formula
AST/ALT ratio = AST (IU/L) ÷ ALT (IU/L)
- AST predominance (ratio ≥2) is characteristic of alcohol-related liver injury.
- Ratio ≈1 is common in chronic viral hepatitis, DILI, and metabolic dysfunction-associated steatosis.
- ALT predominance (ratio <1) often appears in early hepatic injury with preserved synthetic function.
Full Description
AST (aspartate aminotransferase) is present in liver, cardiac, and muscle tissue; ALT (alanine aminotransferase) is more liver-specific. The AST/ALT ratio assists in distinguishing alcoholic hepatitis from other causes and hints at fibrosis severity when interpreted with platelet count and imaging.
Limitations include confounding by hemolysis, muscle injury, medications (statins), and advanced age. Always review patient history, comorbidities, and other biomarkers such as GGT, alkaline phosphatase, and bilirubin for comprehensive assessment.
Frequently Asked Questions
Do elevated ratios always indicate alcohol use?
No. Cirrhosis from viral hepatitis or metabolic causes can also elevate the ratio. Correlate with clinical history.
Should I repeat testing after abstinence?
Yes. In suspected alcohol-related injury, repeat AST/ALT after 2–4 weeks of abstinence to evaluate normalization.
Can muscle injury affect the ratio?
Absolutely. Rhabdomyolysis or intense exercise elevates AST disproportionately. Check CK levels when in doubt.
How does the ratio guide biopsy decisions?
High ratios prompt further evaluation but are not definitive. Combine with imaging and fibrosis scores before deciding on biopsy.