Maddrey's Discriminant Function Calculator

Reviewed by the CalculatorHub team, edited by James Graham. Maddrey discriminant function from prothrombin time and bilirubin. Last verified 19 June 2026.

Maddrey's discriminant function (mDF) is a score used to assess the severity of alcoholic hepatitis and to identify patients who may benefit from corticosteroid treatment. It combines the patient's prothrombin time, a control prothrombin time, and serum bilirubin. A value of 32 or more traditionally marks severe disease. This tool computes the function from your entered values; treatment decisions belong to a clinician.

Patient prothrombin time (seconds)

Control prothrombin time (seconds)

Serum bilirubin (mg/dL)

Maddrey discriminant function

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Maddrey discriminant function formula

mDF = 4.6 * (patient PT - control PT) + serum bilirubin

Prothrombin times are in seconds and serum bilirubin is in milligrams per decilitre (mg/dL). The factor 4.6 weights the prolongation of the prothrombin time relative to control. The result is a unitless score.

Worked example

For a patient prothrombin time of 20 seconds, control of 12 seconds, and bilirubin of 8 mg/dL: mDF = 4.6 * (20 - 12) + 8 = 4.6 * 8 + 8 = 36.8 + 8 = 44.80. A value of 32 or more is traditionally regarded as severe alcoholic hepatitis.

Frequently asked questions

What does a Maddrey score of 32 or more mean?

A discriminant function of 32 or above has traditionally defined severe alcoholic hepatitis associated with higher short-term mortality, and is the threshold often used to consider corticosteroid therapy. The decision is clinical and considers contraindications and other scores.

What bilirubin units does it use?

Milligrams per decilitre (mg/dL). If your laboratory reports bilirubin in micromoles per litre, convert before entering, since the constant in the formula assumes mg/dL.

Why include a control prothrombin time?

Prothrombin time reagents and analysers vary between laboratories, so the patient's value is compared to that laboratory's control to make the prolongation meaningful.

Is this a treatment recommendation?

No. It computes the discriminant function from values you enter. Whether to treat, and with what, is a clinical decision made by a qualified clinician.

Sources

U.S. National Library of Medicine, StatPearls: Alcoholic Hepatitis.
U.S. National Institute on Alcohol Abuse and Alcoholism: NIAAA.

Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. Educational tool, not medical advice. See our methodology.