Maddrey Discriminant Function (MDF) Calculator
Formula: MDF = 4.6 × (Patient PT − Control PT) + Total Bilirubin (mg/dL)
This tool is educational and should not replace professional clinical judgment.
What is the Maddrey Calculator?
The Maddrey calculator estimates the Maddrey Discriminant Function (MDF), a clinical score used in patients with suspected alcohol-associated hepatitis. It helps identify people at higher risk of short-term mortality and can support decisions about urgent specialist evaluation and treatment options.
How the score is calculated
MDF formula
MDF = 4.6 × (Patient PT − Control PT) + Total Bilirubin (mg/dL)
- Patient PT: the patient’s prothrombin time in seconds.
- Control PT: the laboratory reference/control prothrombin time in seconds.
- Total bilirubin: entered in mg/dL (or converted from µmol/L in this calculator).
If bilirubin is provided in µmol/L, this page converts it using: mg/dL = µmol/L ÷ 17.1.
How to use this calculator
- Enter the patient PT value in seconds.
- Enter the control PT value in seconds.
- Enter total bilirubin and choose the correct unit.
- Click Calculate MDF to view the score and interpretation.
Interpreting the result
- MDF < 32: generally lower short-term risk compared with severe disease. Ongoing supportive care and monitoring are still important.
- MDF ≥ 32: suggests severe alcohol-associated hepatitis and higher short-term mortality risk. This level often prompts urgent hepatology assessment and consideration of therapy when appropriate.
Many clinicians combine MDF with other tools (such as MELD and Lille score) and overall clinical context before making treatment decisions.
Clinical caveats and limitations
Why context matters
- The MDF is a risk-stratification aid, not a stand-alone diagnosis.
- Lab timing, assay differences, and data entry errors can change the score.
- Comorbid conditions (infection, bleeding, kidney injury, etc.) strongly influence outcomes.
- Treatment suitability (for example, corticosteroids) depends on contraindications and response monitoring.
Safety note
If this calculator is being used in a real patient scenario, decisions should be made by qualified clinicians. Patients with jaundice, confusion, GI bleeding, fever, or worsening liver-related symptoms need urgent medical care.
Example calculation
Suppose a patient has PT 24 seconds, control PT 12 seconds, and bilirubin 10 mg/dL:
MDF = 4.6 × (24 − 12) + 10 = 4.6 × 12 + 10 = 55.2 + 10 = 65.2
That result is well above 32, which is consistent with severe disease risk and need for urgent specialist evaluation.
Bottom line
The Maddrey calculator is a quick bedside tool for estimating severity in alcohol-associated hepatitis. Use it accurately, interpret it carefully, and always combine it with full clinical assessment.