The AST/ALT ratio compares two liver enzymes, aspartate aminotransferase (AST) and alanine aminotransferase (ALT), to give a clue that neither number gives on its own. Named the De Ritis ratio after the researcher who described it, it is simply AST divided by ALT, and the pattern often points toward a likely cause of liver stress. It is most useful when at least one of the enzymes is already raised, and it is always read alongside the individual values and the rest of a liver panel. In this article you will learn how to calculate the ratio, what a high or low result usually means, and where its limits lie.
What is the AST/ALT ratio?
AST and ALT are enzymes released into the blood when liver cells are injured. ALT sits mostly inside the liver, so it is fairly liver-specific, while AST is also found in muscle, heart, and red blood cells. Because the two enzymes leak at different rates in different diseases, the ratio between them carries information about the underlying process. To understand each enzyme on its own, see our guides to the AST-Normalbereich and to a high ALT result. The ratio is a companion to those numbers, not a replacement for them.
How to calculate and read your AST/ALT ratio
The calculation is straightforward: divide your AST value by your ALT value, using the same units (U/L) for both. For example, an AST of 60 and an ALT of 30 give a ratio of 2.0. In healthy people the ratio is usually a little below 1, often cited around 0.8. The table below shows the patterns clinicians look for, but treat it as a guide rather than a diagnosis.
| AST/ALT-Verhältnis | Often suggests |
|---|---|
| Below 1 (about 0.8) | Typical fatty liver (MASLD) or early chronic viral hepatitis |
| Ungefähr 1 | Nonspecific; read with the other liver tests |
| Above 1 | Possible progression toward advanced fibrosis or cirrhosis |
| 2 or above | Strongly suggests alcohol-related liver disease, especially with a high GGT |
An online AST/ALT ratio calculator does the same division, so you can check it yourself from your report. The key rule is that the ratio is only meaningful when at least one enzyme is raised: dividing two low-normal numbers can produce a value that looks alarming but means little.
What a high AST/ALT ratio means
A ratio at or above 2 is a classic sign of alcohol-related liver disease. In this pattern AST rises out of proportion to ALT, partly because heavy alcohol use depletes a vitamin (B6) that ALT depends on, and the finding is more convincing when the GGT enzyme is also high. Studies of alcohol-related liver disease find a ratio above 1 in the large majority of cases and above 2 in most advanced cases.
A ratio that climbs above 1 in someone with chronic liver disease can also signal a shift toward advanced scarring. In chronic hepatitis B or C, the ratio is usually below 1 early on and tends to cross above 1 as the disease progresses to cirrhosis. Because AST is present in muscle, a high ratio can occasionally reflect muscle injury rather than the liver, which is one reason it is never read in isolation. If your ALT is also raised, our guide on a high ALT result covers the wider list of causes.
What a low AST/ALT ratio means
A ratio below 1 is the usual picture in metabolic dysfunction-associated steatotic liver disease (MASLD), the current name for most fatty liver, where ALT tends to run higher than AST. It is also common early in chronic viral hepatitis. A low ratio is generally more reassuring than a high one, but it still points to a liver process worth understanding, especially alongside metabolic risk factors such as excess weight or diabetes.
Does the ratio matter if AST and ALT are normal?
For everyday clinical use, the ratio is interpreted only when at least one enzyme is elevated, so a striking ratio built from two normal values usually should not be over-read. That said, large population studies have found that even within the normal range, people with a relatively higher ratio tend to have somewhat worse long-term outcomes, which is an area of active research rather than a reason for alarm. The practical takeaway is to focus first on whether AST or ALT is actually raised, and to discuss any borderline pattern with your clinician alongside the full Leberfunktionstests.
Neueste wissenschaftliche Fortschritte
Recent research has extended the De Ritis ratio well beyond the liver, into a broader marker of risk. Here is what it adds, in plain terms.
A 2022 review gathered the evidence linking a higher AST/ALT ratio to cardiovascular disease. It found that an elevated ratio is associated with a greater long-term risk of heart disease and of death, and it may reflect underlying metabolic problems that standard risk factors do not fully capture. In everyday terms, the ratio may be an early, indirect signal of cardiometabolic strain. A 2025 study of more than 2,700 US adults with chronic kidney disease reached a similar conclusion: those with the highest ratios had a meaningfully higher risk of death, including from cardiovascular causes, than those with the lowest. A 2024 clinical review pulled this together, describing the ratio as a simple, low-cost marker with growing prognostic value across liver, heart, and muscle conditions, while stressing that it still needs standard reference ranges and careful interpretation. These are research findings that continue to be refined, and the ratio remains a supporting clue rather than a stand-alone test.
Glossar
- AST/ALT ratio: aspartate aminotransferase divided by alanine aminotransferase, also called the De Ritis ratio.
- AST (aspartate aminotransferase): a liver enzyme also found in muscle, heart, and red blood cells.
- ALT (alanine aminotransferase): a more liver-specific enzyme, also known as SGPT.
- De Ritis ratio: the historical name for the AST/ALT ratio.
- GGT: gamma-glutamyl transferase, an enzyme that helps confirm alcohol-related liver injury.
- MASLD: metabolic dysfunction-associated steatotic liver disease, the current name for most fatty liver.
- Cirrhosis: advanced scarring of the liver.
Häufig gestellte Fragen
What is a normal AST/ALT ratio? In healthy people it is usually a little below 1, often around 0.8. The ratio matters most when at least one of the two enzymes is raised.
What does an AST/ALT ratio above 2 mean? It strongly suggests alcohol-related liver disease, particularly when the GGT enzyme is also high. It should be confirmed with your clinician and the rest of your liver panel.
What does a ratio below 1 mean? It is the typical pattern of fatty liver (MASLD) and early chronic viral hepatitis, where ALT tends to be higher than AST.
How do I calculate my AST/ALT ratio? Divide your AST value by your ALT value, using the same units. An AST of 48 and an ALT of 32, for example, give a ratio of 1.5.
Why is AST higher than ALT in cirrhosis? As scarring advances, the liver clears AST less efficiently and ALT production can fall, so the ratio often rises above 1 even when the enzymes themselves are only modestly elevated.
Does the ratio matter if my enzymes are normal? Mostly no, for clinical decisions. A ratio built from two normal values should not be over-interpreted, though research suggests very subtle long-term associations.
Weiterführende Literatur
- AST normal range explained
- High ALT: causes and warning signs
- ALT levels: meaning and normal ranges
- Liver function tests overview
- SGPT: the ALT enzyme by another name
Quellen
- Lala V, Zubair M, Minter DA. Liver Function Tests. StatPearls, NIH National Library of Medicine, 2023. https://www.ncbi.nlm.nih.gov/books/NBK482489/
- Cleveland Clinic. Alanine Transaminase (ALT) Blood Test. https://my.clevelandclinic.org/health/diagnostics/22028-alanine-transaminase-alt
- MedlinePlus, NIH National Library of Medicine. ALT Blood Test. https://medlineplus.gov/lab-tests/alt-blood-test/
- Ndrepepa G. De Ritis ratio and cardiovascular disease: evidence and underlying mechanisms. J Lab Precis Med, 2022. https://consensus.app/papers/details/e0f2d68b37d551fd9070630fc5ee6d38/
- Shaikh S, et al. Navigating Disease Management: A Comprehensive Review of the De Ritis Ratio in Clinical Medicine. Cureus, 2024. https://consensus.app/papers/details/74678c2339605ef998197abce7df99e6/
- Li Q, et al. Association between De-Ritis ratio (AST/ALT) and mortality in patients with chronic kidney disease. Scientific Reports, 2025. https://consensus.app/papers/details/5830a108a9d55ecbb12895401dd7fead/
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