Calculate Maddrey’s discriminant function (mDF) from prothrombin time and total bilirubin to assess alcoholic hepatitis severity against the DF 32 threshold.
Maddrey’s Discriminant Function Formula
The score comes from the patient’s prothrombin time, the laboratory control prothrombin time, and total serum bilirubin:
mDF = 4.6 * (PT_patient - PT_control) + TB
The calculator can also back-solve the value that reaches a discriminant function of exactly 32. To find the bilirubin that would reach 32:
TB = 32 - 4.6 * (PT_patient - PT_control)
To find the prothrombin time prolongation that would reach 32:
PT_prolongation = (32 - TB) / 4.6
- mDF: the modified Maddrey’s discriminant function, a unitless prognostic score.
- PT_patient: the patient’s prothrombin time in seconds.
- PT_control: the laboratory’s control or reference prothrombin time in seconds, often near 12 seconds.
- TB: total serum bilirubin in mg/dL. If your value is in micromol/L, divide by 17.1 to convert to mg/dL.
- PT_prolongation: the patient PT minus the control PT, in seconds.
The score mode multiplies the prothrombin time prolongation by 4.6, adds total bilirubin, and compares the total to 32. The two back-solve modes hold one input fixed and return the other value that lands exactly on 32, which shows how close a patient sits to the severe threshold.
mDF Score Interpretation
The cutoff of 32 separates severe from non-severe disease. Use the ranges below as general guidance alongside the full clinical picture.
| mDF value | Severity | Approx. 30-day mortality | Typical consideration |
|---|---|---|---|
| Below 32 | Non-severe | Roughly 10% or less | Supportive care, abstinence, and nutrition; corticosteroids not indicated by this score |
| 32 or higher | Severe | About 35% to 45% | Consider corticosteroids if no contraindication; reassess with the Lille score near day 7 |
How mDF Compares to Other Alcoholic Hepatitis Scores
The discriminant function is one of several scores used in alcoholic hepatitis. The others use overlapping but different inputs, so a borderline mDF is often read next to one of them.
| Score | Inputs | Severe threshold | Main use |
|---|---|---|---|
| Maddrey mDF | PT, control PT, bilirubin | 32 or higher | Flag severe disease and steroid candidates at baseline |
| MELD | Bilirubin, INR, creatinine | About 20 or higher | General end-stage liver disease and mortality risk |
| Glasgow (GAHS) | Age, WBC, urea, PT ratio, bilirubin | 9 or higher | Refine baseline risk, often alongside mDF |
| ABIC | Age, bilirubin, INR, creatinine | 6.71 and 9.0 cut points | Split low, intermediate, and high risk |
| Lille | Age, albumin, bilirubin day 0 and 7, creatinine, PT | Above 0.45 at day 7 | Judge steroid response after about 7 days |
The mDF tells you whether to start steroids at baseline, while the Lille score judges at day 7 whether they are working, which is why the two are commonly used in sequence.
Example Problems
Example 1, score mode. A patient has a prothrombin time of 22 seconds against a control of 12 seconds and a total bilirubin of 14 mg/dL. The prolongation is 22 minus 12, or 10 seconds. The PT term is 4.6 times 10, which is 46. Adding bilirubin gives 46 plus 14, so mDF = 60. Because 60 is above 32, this is severe alcoholic hepatitis.
Example 2, threshold mode. A patient has a prothrombin time of 15 seconds against a control of 12 seconds, so the prolongation is 3 seconds. To find the bilirubin that would reach the severe cutoff, compute 32 minus 4.6 times 3, which is 32 minus 13.8, or 18.2. A total bilirubin of about 18.2 mg/dL would bring the discriminant function to 32.
Frequently Asked Questions
What counts as a severe Maddrey’s score?
A value of 32 or higher is classed as severe alcoholic hepatitis. It carries a reported 30-day mortality near 35% to 45% and marks the point at which corticosteroid therapy is usually considered if there is no contraindication such as active infection or gastrointestinal bleeding. Below 32 the short-term outlook is better and steroids are generally not started on the basis of this score alone.
Should I enter prothrombin time in seconds or use the INR?
The original formula uses prothrombin time in seconds compared with the laboratory control, so that is what this calculator expects. Because PT reagents differ between labs, the same patient can produce different prolongations, which is why the control value matters and why some centers prefer INR-based scores such as MELD or ABIC for a second read. Enter the patient PT and your lab’s control PT in the same units of seconds.
What bilirubin value do I use, and how do I convert from micromol/L?
Use total serum bilirubin, not the direct fraction. If your laboratory reports bilirubin in micromol/L, divide by 17.1 to get mg/dL, or select micromol/L in the calculator and it converts the value for you. As an example, 240 micromol/L is about 14 mg/dL.