AST/ALT Ratio Calculator
Compute the AST/ALT (DeRitis) ratio — a simple screen for type and severity of liver injury.
What is AST/ALT Ratio?
The AST/ALT ratio, also called the DeRitis ratio, was first described in 1957 and remains a useful pattern-recognition tool today. ALT is more liver-specific and tends to be higher than AST in most chronic liver disease. When AST exceeds ALT, it can indicate alcoholic liver disease, advanced fibrosis or cirrhosis, or non-hepatic causes such as muscle injury or rhabdomyolysis.
How is it calculated?
Ratio = AST / ALT (both in U/L). General interpretation: < 1 typical of viral hepatitis or NAFLD; 1–2 possible cirrhosis or alcohol-related disease; > 2 strongly suggestive of alcoholic liver disease (especially with macrocytic anaemia).
Frequently Asked Questions
- Does an AST/ALT > 2 always mean alcohol?
- No — muscle injury, hyperthyroidism and Wilson disease can also raise the ratio.
- Is a low ratio reassuring?
- Not necessarily — early NAFLD typically has ALT > AST.
- How is the ratio used clinically?
- As a quick orientation in workup; not diagnostic on its own.
- Should I be concerned with an elevated ratio?
- Discuss with your physician — context and trends matter.