Maddrey's Discriminant Function Calculator
Grade the severity of alcohol-associated (alcoholic) hepatitis with Maddrey’s discriminant function (mDF), the classic score that identifies patients at high short-term mortality who may benefit from corticosteroids. It combines the prothrombin time with the serum bilirubin. Enter the patient’s and the laboratory’s control prothrombin time and the total bilirubin to get the score and whether it crosses the treatment threshold of 32.
About Maddrey's function
The discriminant function was the first score to identify severe alcoholic hepatitis likely to benefit from corticosteroids. Source: Maddrey WC et al., “Corticosteroid therapy of alcoholic hepatitis,” Gastroenterology 1978;75(2):193–199 (modified form).
Frequently asked questions
What is Maddrey's discriminant function formula?
Maddrey’s discriminant function is mDF = 4.6 × (patient prothrombin time − control prothrombin time) + total bilirubin in mg/dL, with the prothrombin times in seconds. For example, a patient PT of 20 s, a control PT of 12 s and bilirubin of 15 mg/dL gives 4.6 × (20 − 12) + 15 = 51.8. The 4.6 coefficient scales the prolongation of the prothrombin time so that the clotting defect and the degree of jaundice both drive the result. Because the formula uses the difference between the patient and control times rather than an INR, both prothrombin values must come from the same laboratory report.
What does the score mean?
An mDF of 32 or more indicates severe alcohol-associated hepatitis with a high short-term mortality — roughly 35–45% at one month — and is the usual threshold for considering corticosteroid treatment. A value under 32 indicates milder disease with a better prognosis, where steroids are generally not used. The threshold of 32 comes from the original steroid trials, in which patients above it were the group shown to benefit and those below it were not. Crossing it should prompt a search for infection, renal failure and gastrointestinal bleeding before any steroid is started, with the response reassessed by the Lille model after seven days.
Why does the control prothrombin time matter?
The score uses the difference between the patient’s prothrombin time and the laboratory’s control (reference) value, so the control used affects the result and whether the threshold of 32 is crossed. Different labs report different controls, which is one reason the same patient can score differently between hospitals — always use the control from the same report. Because the difference is multiplied by 4.6, a one-second error in the control value shifts the score by 4.6 points, enough to cross the threshold of 32 in a borderline case. If your report gives only an INR, ask for the prothrombin time in seconds alongside the laboratory control rather than converting the INR back.
How does mDF compare with other scores?
Maddrey’s function is the oldest and simplest severity score for alcoholic hepatitis. Newer tools such as the MELD score, the Glasgow Alcoholic Hepatitis Score and the Lille model (which assesses response to steroids after 7 days) are also widely used and may predict outcome better; many clinicians look at more than one. See our MELD and MELD 3.0 calculators.
What if my bilirubin is in SI units?
Convert bilirubin from µmol/L to mg/dL by dividing by 17.1 (so 250 µmol/L ≈ 14.6 mg/dL), then enter the mg/dL value. Prothrombin times are already in seconds. This calculator is an educational reference, not medical advice.
This is a reference tool, not a diagnosis or medical advice. Results depend on the laboratory, assay and clinical context, and reference intervals vary between labs and by age and sex — always read your result against the range printed on your own report and discuss it with a qualified healthcare professional.
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