How this calculator works
The De Ritis ratio divides aspartate aminotransferase by alanine aminotransferase from the same clinical assessment. Both values must use the same enzyme-activity units. The quotient is dimensionless. It does not identify a cause of liver injury on its own, and it is especially unstable when ALT is very low. The original ratio predates modern disease-specific diagnostic pathways. The result is an estimate for information only and is not medical advice.
Formula
AST/ALT ratio = AST / ALT. AST = ratio x ALT. ALT = AST / ratio. ALT must be greater than zero.
Worked example
AST 80 U/L and ALT 40 U/L give a ratio of 2. AST 30 and ALT 60 give 0.5.
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Frequently asked questions
Does a high ratio prove alcohol-related disease?
No. Multiple conditions and non-liver factors can alter AST and ALT.
Are U/L and IU/L numerically interchangeable here?
Use the laboratory's matching activity units and method. Never enter a concentration or volume as an enzyme activity.
Why is division by zero rejected?
ALT equal to zero has no defined finite ratio. Likewise a zero ratio cannot uniquely recover ALT.