Maddrey Discriminant Function Calculator
Free online discriminant function calculator — a Maddrey score calculator for alcoholic hepatitis severity and prognosis. This discriminant function liver calculator implements the alcoholic hepatitis discriminant function: the Maddrey score alcoholic hepatitis researchers published in 1978 remains the standard severity score. Enter PT (patient & control, in seconds) and total bilirubin to get the Maddrey DF score — this DF score liver calculator also shows a full component breakdown and the published severity interpretation. Use it as an alcoholic hepatitis severity calculator or alcoholic hepatitis prognosis calculator when studying the discriminant function liver disease severity score.
Looking for a Maddrey score calculator free online with the full component breakdown? Use this discriminant function calculator online free, with no sign-up — every calculation happens in your browser and nothing is uploaded or stored.
Educational tool — not medical advice. This Maddrey DF calculator is for learning and double-checking hand calculations only. It does not diagnose any condition, does not rule out liver disease, and must not be used to decide treatment. Severity assessment and any therapy decision belong to a qualified physician. If you have liver symptoms, seek medical care.
Calculate the discriminant function
| PT prolongation (patient − control) | – |
| PT part: 4.6 × prolongation | – |
| Bilirubin part (mg/dL) | – |
| DF total | – |
Worked examples — Maddrey discriminant function example calculations
Tap an example to load it into this DF calculator for alcoholic hepatitis. Each DF calculator alcoholic hepatitis example below uses verified values.
The discriminant function formula for liver severity
Maddrey discriminant function explained simply: it turns two lab numbers — PT prolongation and bilirubin — into one severity score. So what is Maddrey discriminant function scoring for? Estimating short-term severity in alcoholic hepatitis, nothing more.
Also described in search as the discriminant function formula liver score, the discriminant function 4.6 formula, or the pt bilirubin discriminant function, it always uses the same two inputs. Note that the Maddrey discriminant function PT seconds control value must come from the same laboratory run as the patient PT. The Maddrey score components PT bilirubin weighting is visible in the breakdown above: 4.6 multiplies the PT prolongation, while bilirubin enters unweighted. The PT prolongation Maddrey score input is simply patient PT minus control PT, in seconds.
Maddrey score interpretation
The published severity threshold is 32. The Maddrey discriminant function threshold 32 is the published cut point: a discriminant function severe alcoholic hepatitis label applies when DF is above 32, per guidelines. The Maddrey DF above 32 meaning is straightforward — per published guidelines it marks severe disease, the group in which corticosteroids may be considered, per guidelines; the treatment decision is made by a physician. In plain terms, the Maddrey score severe vs mild split works like this: a DF above 32 identifies severe alcoholic hepatitis, while a DF of 32 or below is at/below the threshold. It is not a discriminant function test for liver diagnosis — it is a severity score, and this discriminant function corticosteroid indication is a guideline classification, not a prescription.
Scope boundary — what this tool is not
The discriminant function for liver disease severity answers one specific question. Related scores answer different ones. Common comparisons — Maddrey discriminant function vs MELD score, Maddrey discriminant function vs Child Pugh, and discriminant function vs Lille score — are summarized below: each answers a different clinical question and none replaces the others.
| Score | What it measures | Different from Maddrey DF |
|---|---|---|
| Child-Pugh | Cirrhosis severity (5 parameters) | Chronic disease grading, not alcoholic-hepatitis severity |
| APRI | Liver fibrosis screening (AST/platelets) | Screening test, not a severity score |
| MELD / MELD-Na | Mortality & transplant allocation | Different formula and purpose |
| Lille score | Steroid response at day 7 | Treatment-response, not baseline severity |
This tool computes only the Maddrey discriminant function (PT seconds + bilirubin). It does not compute MELD, Child-Pugh, APRI, or Lille.
Frequently asked questions
What is the Maddrey discriminant function?
The Maddrey discriminant function is a published clinical score used to estimate the severity of alcoholic hepatitis. It combines how prolonged the prothrombin time (PT) is with the total bilirubin level into a single number, the DF. This calculator is a free online educational implementation of that formula.
What is the Maddrey discriminant function formula?
The formula is DF = 4.6 x (PT of the patient in seconds minus PT of the control in seconds) + total bilirubin in mg/dL. If the patient PT is lower than the control PT, the difference is treated as zero. For example, a PT difference of 8 seconds and a bilirubin of 12 mg/dL gives 4.6 x 8 + 12 = 48.8.
What does a Maddrey DF above 32 mean?
In published guidelines, a discriminant function above 32 identifies severe alcoholic hepatitis, a group in which corticosteroids may be considered - per guidelines; the treatment decision is made by a physician. A result above 32 is a severity classification from a score, not a diagnosis, and this tool cannot replace clinical judgment.
Can I use INR instead of PT seconds in the Maddrey score?
No. The original Maddrey discriminant function requires prothrombin time in seconds for both the patient and the control, because the 4.6 factor was calibrated on seconds. INR is a standardized ratio and cannot be substituted directly into the formula. If your lab report only shows INR, ask the laboratory for the PT values in seconds.
What bilirubin units does this discriminant function calculator use?
The formula expects total bilirubin in mg/dL. If your result is reported in umol/L, divide by 17.1 to convert - for example, 205.2 umol/L equals 12 mg/dL. This calculator accepts both units and converts automatically.
What if the patient PT is lower than the control PT?
A negative prolongation has no meaning in the formula, so the difference is treated as zero and the score equals the bilirubin value alone. In practice, check that the control PT matches the laboratory's reference before calculating.
Is the Maddrey discriminant function a diagnosis?
No. It is a severity score for people already assessed for alcoholic hepatitis, not a diagnostic test for liver disease. A low score does not rule out liver problems, and a high score does not diagnose them. Always interpret results with a qualified clinician.
How does the Maddrey discriminant function differ from MELD and Child-Pugh?
The Maddrey discriminant function was designed specifically for short-term severity assessment in alcoholic hepatitis using PT and bilirubin. Child-Pugh grades chronic cirrhosis severity from five parameters, MELD estimates mortality for transplant allocation, and the Lille score measures response to steroids on day 7. They answer different clinical questions and cannot replace each other.
What are the components of the Maddrey score?
Two components: the PT part, 4.6 times the PT prolongation in seconds (patient PT minus control PT), and the bilirubin part, the total bilirubin in mg/dL. The breakdown shown by this calculator displays both parts separately so you can see which one drives the score.
What are normal PT and bilirubin values?
Reference ranges vary by laboratory, but PT is commonly around 11 to 13.5 seconds and total bilirubin around 0.3 to 1.2 mg/dL in adults. Typical values do not determine severity by themselves - the discriminant function uses your lab's control PT and your measured values, so confirm the reference ranges on your own report.
What are the limitations of the discriminant function?
It is a single score from 1978 that does not account for infection, kidney injury, or other factors that influence prognosis in alcoholic hepatitis. Later tools such as the Lille score add treatment-response information. Because of these limits, guidelines use the DF as one input among several, never as the sole basis for care.
Who is this Maddrey DF calculator for?
It is built for education: clinicians double-checking a hand calculation, medical students learning the formula, and anyone studying how the score works. It is not intended for self-diagnosis or for making treatment decisions without a physician, and it stores nothing - every calculation happens in your browser.
Free tool by NRTechStudio