26 De Ritis ratio (ASTALT)

De Ritis ratio AST/ALT: what values below 1 and above 2 suggest about the type of liver injury.

The De Ritis ratio is the ratio of AST to ALT activity in the blood. It was described in 1957 by the Italian physician Fernando De Ritis in patients with viral hepatitis. The ratio does not show how much liver damage there is, but it helps to suggest what kind of damage. In most liver diseases ALT is higher than AST, giving a ratio below 1. In alcoholic liver disease, advanced fibrosis and cirrhosis, and injury outside the liver, AST predominates.

Liver function testsAST/ALT ratioAlcoholic liver disease

FormulaAST (U/L) / ALT (U/L)

Healthy peoplearound 1 (≈ 0.8–1.2)

Below 1fatty liver, viral hepatitis

Above 2suggests alcoholic liver disease

Figure 1. Interpretation of the AST/ALT ratio. It is meaningful mainly when transaminases are raised; with normal values the ratio is less informative.

Why the ratio changes

ALT is concentrated in the cytoplasm of liver cells and has a longer half-life in blood than AST, so it rises more in acute and chronic hepatitis and fatty liver.
Alcohol damages mitochondria, which contain much of the AST, and depletes vitamin B₆, needed for ALT activity. Both effects increase the ratio.
In advanced fibrosis and cirrhosis, reduced clearance of AST raises the ratio regardless of cause.
AST also comes from muscle, heart and red blood cells, so muscle injury, myocardial infarction or haemolysis raise the ratio without liver disease.

Clinical significance

A ratio above 2, especially with a raised GGT and an increased red cell size (MCV), strongly suggests alcohol-related liver injury. A rising ratio in chronic liver disease may signal progression to cirrhosis. The ratio is a guide, not a diagnosis; it is interpreted together with history, other tests and imaging.

What to do

Discuss an abnormal ratio with your doctor, especially if transaminases are raised. Be open about alcohol use, medicines and supplements; this helps find the cause quickly.

References

Botros M, Sikaris KA. The De Ritis ratio: the test of time. Clin Biochem Rev. 2013;34(3):117–130. PMID: 24353357
Kwo PY, Cohen SM, Lim JK. ACG clinical guideline: evaluation of abnormal liver chemistries. Am J Gastroenterol. 2017;112(1):18–35. doi:10.1038/ajg.2016.517

This article is for general information and does not replace a consultation with a doctor. Laboratory results must be interpreted by a physician together with symptoms and other tests.

Published on 30 April 2024