Maddrey Discriminant Function Calculator

Estimate Maddrey discriminant function from patient prothrombin time, control prothrombin time, and bilirubin or bile acid input.

860.0K uses Updated · 2026-05-25 Runs locally · zero upload
AD

How to Use the Maddrey Discriminant Function Calculator

Enter the patient prothrombin time and the laboratory control prothrombin time in seconds. Then choose the analyte and enter the bilirubin or bile acid value; bilirubin can be entered in mg/dL or μmol/L.

After calculation, compare the DF value with the 32-point severe-risk cutoff. A result at or above 32 is commonly treated as a warning sign for severe alcoholic hepatitis, while lower results still need clinical context.

Formula and Method - Maddrey Discriminant Function Calculator

DF = 4.6 × (patient prothrombin time - control prothrombin time) + bilirubin in mg/dL equivalent

Maddrey DF combines delayed clotting with bilirubin burden. A larger prothrombin-time gap reflects impaired hepatic synthetic function, while higher bilirubin reflects worse cholestasis or hepatocellular injury. When bilirubin is entered in μmol/L, the calculator divides by 17.1 before applying the formula.

Use Cases for the Maddrey Discriminant Function Calculator

  • Screening whether a patient crosses the DF ≥ 32 severe alcoholic hepatitis threshold.
  • Checking how much of the score is driven by prothrombin-time prolongation versus bilirubin.
  • Teaching why two patients with similar bilirubin can have different DF values when clotting time differs.

Frequently asked questions about Maddrey Discriminant Function Calculator

Which bilirubin unit should I use?

Use mg/dL directly, or select μmol/L so the calculator can convert it to a mg/dL equivalent.

What does DF ≥ 32 mean?

It is a commonly used severe-risk signal that should prompt clinical review, not a standalone treatment decision.

Can bile acid replace bilirubin?

Classic Maddrey DF uses bilirubin. If bile acid is used for the requested workflow, the result should be labeled accordingly.