What is the AST/ALT ratio and what does it show?

The AST/ALT ratio (also called the De Ritis ratio) is the value of AST (aspartate aminotransferase) divided by ALT (alanine aminotransferase). Both are liver enzymes measured in U/L on a standard blood test. The ratio is used as one indicator of the likely cause of liver injury: a ratio below 1 often suggests viral hepatitis or non-alcoholic fatty liver disease (NAFLD); a ratio between 1 and 2 is non-specific and may indicate non-alcoholic liver disease; a ratio above 2 is classically associated with alcoholic liver disease. The ratio is a screening pattern and must always be interpreted alongside other clinical findings by a doctor.

What are normal AST and ALT levels?

Normal reference ranges vary slightly between laboratories, but typical adult ranges are: AST 10 to 40 U/L and ALT 7 to 56 U/L. Men tend to have slightly higher upper limits than women. In healthy individuals with both values within the normal range, the ratio is typically close to 1. Elevated enzymes with a ratio pattern outside the normal range prompt further investigation, but many factors including muscle injury (AST is also found in muscle) can affect results.

Can a high AST/ALT ratio always mean alcoholic liver disease?

No. While an AST/ALT ratio above 2 is a classic finding in alcoholic hepatitis, the ratio is not diagnostic on its own. AST is also released from muscle, heart, and red blood cells, so conditions like myocardial infarction, rhabdomyolysis (severe muscle breakdown), or haemolysis can raise the ratio without any liver disease present. Cirrhosis from any cause can also produce an elevated ratio as the liver architecture is disrupted. A ratio above 2 warrants further evaluation by a healthcare professional, including additional tests such as gamma-GT, bilirubin, and imaging.

AST/ALT Ratio Calculator

This calculator works out your AST/ALT ratio, also known as the De Ritis ratio, from a standard liver function blood test, giving you one indicator of the pattern behind any raised liver enzymes. You enter your AST (aspartate aminotransferase) and ALT (alanine aminotransferase) results in U/L exactly as they appear on your lab report, plus your sex, which sets the reference range used to flag each enzyme as below, within, or above normal. The calculator returns your AST/ALT ratio to two decimal places, shown on a visual scale from 0 to 3 and above, alongside a breakdown of the values entered and the simple AST divided by ALT formula behind the result. It also matches your ratio against the three recognised patterns: below 1.0, which leans towards viral hepatitis or fatty liver disease; 1.0 to 2.0, a non-specific range; and above 2.0, the classic alcoholic liver disease pattern, with a plain-language verdict explaining what your figure may suggest. Use it after a blood test to understand your result before or after seeing your doctor, keeping in mind that AST also comes from muscle, heart and blood cells, so a high ratio does not confirm liver disease on its own. This tool is educational only and does not replace a proper medical assessment of your test results.

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Reviewed June 2026 Interpretation thresholds based on established clinical literature (De Ritis et al.; AASLD guidelines).

1. Liver Enzyme Values

AST (Aspartate aminotransferase) U/L

U/L

ALT (Alanine aminotransferase) U/L

U/L

Sex (for reference range)

2. Reference Ranges

Enzyme	Male (U/L)	Female (U/L)
AST	10 to 40	10 to 35
ALT	7 to 56	7 to 45

Reference ranges are typical adult values. Your laboratory may use slightly different ranges; always refer to your lab report.

AST/ALT Ratio Result

AST Value

40 U/L

Within normal range

AST/ALT Ratio
2.00
De Ritis ratio

ALT Value

20 U/L

Within normal range

Ratio 0 1.0 (equal) 2.0 3.0+

Ratio Breakdown

AST entered40 U/L

ALT entered20 U/L

Ratio formulaAST ÷ ALT

AST/ALT Ratio2.00

Interpretation Guide

Ratio below 1.0Viral hepatitis / NAFLD pattern

Ratio 1.0 to 2.0Non-specific / non-alcoholic pattern

Ratio above 2.0Alcoholic liver disease pattern

Your patternAbove 2.0 (AST-dominant)

Result: Enter your AST and ALT values above.

What is the AST/ALT Ratio?

The AST/ALT ratio (also known as the De Ritis ratio, after Italian physician Fernando De Ritis who first described its clinical significance in 1957) is calculated by dividing the serum AST level by the serum ALT level. Both values are routinely measured in a standard liver function test (LFT) or comprehensive metabolic panel.

The ratio is useful because AST and ALT are both found in liver cells, but they are also found in different concentrations in other tissues. ALT is more specific to the liver, while AST is also present in muscle, heart tissue, and red blood cells. When different types of liver injury occur, the two enzymes are released in different proportions, producing a characteristic ratio pattern.

Formula

The calculation is straightforward:

AST/ALT Ratio = AST (U/L) ÷ ALT (U/L)

Both values must be in the same units (U/L, which is standard for routine blood tests). There is no weighting or adjustment for age or sex in the basic ratio.

Interpreting Your Ratio

AST/ALT Ratio	Typical Pattern	Possible Associations
Below 1.0	ALT-dominant elevation	Viral hepatitis (hepatitis A, B, C), non-alcoholic fatty liver disease (NAFLD), early non-alcoholic steatohepatitis (NASH)
1.0 to 2.0	Non-specific elevation	Non-alcoholic liver disease, mild hepatitis, early cirrhosis, medication-related injury
Above 2.0	AST-dominant elevation	Alcoholic hepatitis, alcoholic cirrhosis, advanced cirrhosis from any cause
Above 2.0 (non-liver)	Non-hepatic AST elevation	Myocardial infarction, rhabdomyolysis, haemolysis (must be excluded)

These patterns are guides, not diagnoses. A ratio above 2 is a classic textbook finding for alcoholic liver disease, but it is not diagnostic. Other conditions, particularly muscle breakdown and heart attacks, can elevate AST without ALT, producing a high ratio with no liver pathology involved. Additional markers such as gamma-GT (GGT), bilirubin, alkaline phosphatase (ALP), total protein, albumin, and imaging are used together by clinicians to build a complete picture.

Normal Reference Ranges

Reference ranges for AST and ALT vary slightly between laboratories, but typical adult values are:

AST: 10 to 40 U/L (men); 10 to 35 U/L (women)
ALT: 7 to 56 U/L (men); 7 to 45 U/L (women)

When both AST and ALT are within the normal range, the ratio is generally close to 1.0 and is unlikely to be clinically significant on its own. The ratio becomes most informative when at least one enzyme is elevated above the normal range.

Worked Example

A patient has a blood test result of AST = 40 U/L and ALT = 20 U/L.

AST/ALT Ratio = 40 / 20 = 2.00

A ratio of exactly 2.0 sits at the threshold typically used to distinguish alcoholic from non-alcoholic liver disease patterns. This result would prompt a clinician to consider alcoholic liver disease alongside other causes, and to review additional findings such as GGT, alcohol history, and imaging. The same defaults are used in this calculator above, producing a ratio of 2.00.

Limitations

The AST/ALT ratio has several important limitations:

It is a pattern indicator, not a diagnostic test. A ratio above 2 does not confirm alcoholic liver disease.
AST is non-specific. Muscle damage, heart disease, and haemolysis all elevate AST without liver involvement.
Advanced cirrhosis from any cause can produce a ratio above 2 due to the loss of hepatocytes that normally produce more ALT than AST.
Some medications and supplements can alter enzyme ratios independently of significant liver injury.
Normal-range values can occur in established liver disease, particularly in chronic hepatitis C.

Always interpret your results with your doctor or healthcare provider, who can review your complete clinical picture.

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Sources and method: De Ritis F, Coltorti M, Giusti G (1957). "An unknown transaminase in rat serum." Science 126:1148. Giannini EG, Testa R, Savarino V (2005). "Liver enzyme alteration: a guide for clinicians." Canadian Medical Association Journal 172(3):367-379. Botros M, Sikaris KA (2013). "The de ritis ratio: the test of time." The Clinical Biochemist Reviews 34(3):117-130.

This calculator is for educational and informational purposes only. It does not constitute medical advice, diagnosis, or treatment. The AST/ALT ratio is one of many clinical indicators used by healthcare professionals. Always consult your doctor or a qualified health professional about your blood test results and any concerns regarding liver health.