AST to ALT Ratio: Clinical Guide

Clinical guide to AST to ALT Ratio including formula, assumptions, units, interpretation, limitations and references.

Calculates the aspartate aminotransferase to alanine aminotransferase ratio.

Overview

Calculates the aspartate aminotransferase to alanine aminotransferase ratio.

Clinical Significance

Provides contextual information in liver injury patterns, but is non-specific and must be interpreted with absolute enzyme values, history and other investigations.

How It Is Calculated

  • AST/ALT ratio = AST / ALT.

Interpretation

  • Provides contextual information in liver injury patterns, but is non-specific and must be interpreted with absolute enzyme values, history and other investigations.

Worked Example

Enter a clinically consistent set of values in the displayed units. MedicalC applies: AST/ALT ratio = AST / ALT.

Limitations

  • This tool does not establish a diagnosis or mandate treatment.
  • Published cut-offs may vary between cohorts and measurement methods.
  • Calculation precision cannot compensate for poor source data.

Clinical Pearls

  • Trend the result over time where clinically appropriate.
  • Record the source values and units alongside the calculated result.

Common Mistakes

  • Using the wrong unit.
  • Combining measurements obtained at different times.
  • Applying a research-derived threshold as a universal treatment trigger.

Frequently Asked Questions

What does this calculator provide?

Calculates the aspartate aminotransferase to alanine aminotransferase ratio.

Can this result be used alone?

No. It must be interpreted with clinical context and appropriate investigations.

What equation is used?

AST/ALT ratio = AST / ALT.

What is the main limitation?

The result depends on valid inputs and may not be calibrated for every population or setting.

References

  1. De Ritis F et al. Serum transaminase activities in liver disease. Lancet. 1957. — Formula, physiological or validation reference.

Reviewed by: MedicalC Clinical Editorial Team
Last reviewed: July 2026

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