Liver Function
(AST/ALT Ratio) Checker
Calculate your De Ritis ratio from AST and ALT lab values and understand what different patterns may suggest about liver health.
| Ratio | Pattern | Commonly Associated With |
|---|---|---|
| < 0.7 | Low | NAFLD, acute viral hepatitis, drug-induced injury |
| 0.7 – 1.2 | Normal range | Healthy individuals; AST and ALT roughly balanced |
| 1.2 – 2.0 | Warrants evaluation | Possible cirrhosis, NASH, progressive liver disease |
| > 2.0 | Alcohol pattern | Classic alcoholic liver disease indicator |
| > 3.0 | High specificity | Alcoholic hepatitis or advanced alcoholic cirrhosis |
The ratio is only clinically meaningful when at least one of AST or ALT is elevated above the normal range for your lab.
What Is the AST/ALT Ratio?
In healthy individuals, the ratio typically falls between 0.7 and 1.2, reflecting roughly balanced AST and ALT levels. Importantly, this ratio is only clinically meaningful when at least one enzyme is elevated above the normal range — a high or low ratio calculated from two enzyme values that are both well within normal limits generally isn't clinically significant and mostly reflects normal individual variation.
What Different Ratio Patterns May Suggest
📉 Ratio Below 1.0
The most common pattern, typically seen in non-alcoholic fatty liver disease (NAFLD), viral hepatitis, and drug-induced liver injury, where ALT rises more than AST.
📈 Ratio Above 2.0
The classic pattern associated with alcoholic liver disease. Alcohol preferentially affects AST production and depletes vitamin B6, which reduces ALT synthesis relative to AST.
Ratios in the 1.0-2.0 range occupy a middle ground and can reflect various conditions including chronic hepatitis, NASH (non-alcoholic steatohepatitis), or progressive fibrosis — research published in Hepatology found a statistically significant correlation between rising AST/ALT ratio and the presence of cirrhosis, since regenerative liver capacity (which produces more ALT) tends to fall as fibrosis and cirrhosis progress, allowing AST to become relatively more dominant even in non-alcoholic conditions.
Why the Ratio Matters More With Context
The AST/ALT ratio is a useful clue, not a standalone diagnosis. Its interpretation genuinely depends on the magnitude of enzyme elevation, not just the ratio value alone. For example, alcoholic liver disease typically shows AST elevated more than 8x the upper normal limit alongside a high ratio, while non-alcoholic fatty liver disease commonly shows both AST and ALT elevated to a similar, more modest degree. Additional lab markers — particularly GGT (gamma-glutamyl transferase), which rises specifically with alcohol use and cholestasis — meaningfully strengthen or weaken the alcoholic liver disease interpretation when combined with a high AST/ALT ratio. Bilirubin, platelet count, and imaging findings all add further context that a ratio alone cannot provide.
UK Reference Ranges and Clinical Use
The NHS and UK laboratories use broadly similar AST and ALT normal reference ranges to those cited in this calculator, though exact upper and lower limits vary somewhat between individual labs and testing methods, which is standard practice internationally rather than a US-UK specific difference. The De Ritis ratio itself is used identically in UK clinical hepatology practice as in the US — it's a well-established, internationally recognized tool rather than one with meaningfully different interpretation guidelines between countries. What does vary somewhat is testing context: routine liver function tests are commonly included in UK NHS health checks and pre-operative screening, meaning many people encounter these values incidentally rather than through symptom-driven testing, which is worth keeping in mind if you're checking a ratio from a routine panel rather than a targeted liver workup.
A Single Reading vs. Trends Over Time
It's worth being clear that a single AST/ALT ratio reading offers limited information compared to tracking the trend over multiple tests. Liver enzyme levels can fluctuate meaningfully based on recent alcohol intake, exercise, medication changes, and even normal day-to-day variation, so a single elevated ratio isn't necessarily representative of an ongoing pattern. Clinicians generally place more diagnostic weight on a ratio that's consistently elevated across repeat testing, alongside a stable or worsening trend in the absolute enzyme values, than on any single isolated reading — which is exactly why your doctor may recommend repeat testing before drawing firm conclusions from an initial abnormal result, rather than immediately pursuing extensive additional workup based on one data point.
Other Factors That Can Affect the Ratio
- Muscle injury or intense recent exercise — since AST is also present in muscle tissue, strenuous exercise or muscle damage can elevate AST independent of liver status, raising the ratio without reflecting liver disease
- Medications — statins and various other drugs can affect liver enzymes and shift the ratio
- Acute vs chronic conditions — the pattern can shift over the course of an illness; in alcoholic hepatitis specifically, AST typically exceeds ALT unless several days have passed without alcohol exposure, at which point ALT may rise above AST
- Vitamin B6 (pyridoxine) status — deficiency reduces ALT enzyme activity specifically, which can artificially raise the AST/ALT ratio independent of true liver pathology
Related Kidney and Metabolic Context
Liver function assessment often occurs alongside broader metabolic workups. If your evaluation also includes kidney function, our eGFR Kidney Function Calculator can help interpret that result. Since alcohol use is directly relevant to AST/ALT interpretation, our Alcohol Units Calculator can help you track consumption against weekly guidelines, and metabolic conditions like insulin resistance often co-occur with NAFLD — see our HOMA-IR Calculator for that connection.
Frequently Asked Questions
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