About Maddrey's Discriminant Function
Maddrey's Discriminant Function (DF), first published by Maddrey and colleagues in 1978, is a bedside formula used in hepatology to estimate the severity of alcoholic (alcohol-associated) hepatitis and to help identify patients most likely to benefit from corticosteroid therapy. It combines two markers of liver synthetic function and cholestasis — the prothrombin time (PT) and the total serum bilirubin — into a single score. A DF of 32 or higher is the long-standing threshold for "severe" alcoholic hepatitis, historically associated with roughly a 30-50% risk of death within one month if left untreated.
The formula
DF = 4.6 × (patient's PT in seconds − control PT in seconds) + total serum bilirubin (mg/dL). The "control PT" is the normal/reference prothrombin time used by the lab that ran the test (commonly around 12 seconds, though this varies by laboratory and reagent — always use the control value reported alongside your own PT result, not a generic assumption). If your bilirubin is reported in µmol/L, this calculator converts it to mg/dL (dividing by 17.1) before applying the formula, since the original equation was derived using mg/dL.
Interpreting the score
A DF below 32 generally corresponds to mild-to-moderate alcoholic hepatitis, where supportive care (alcohol cessation, nutrition, monitoring) is typically sufficient. A DF of 32 or higher identifies severe disease; in this range, clinicians often evaluate patients for corticosteroids such as prednisolone (if no contraindication like active infection or GI bleeding exists) or pentoxifylline as an alternative, and frequently reassess response using the Lille score after about seven days of treatment. Other tools such as the MELD score are also used alongside or instead of the DF in some centers.
Important limitations
This calculator performs the arithmetic only — it does not diagnose alcoholic hepatitis, does not replace a full clinical assessment (history, exam, imaging, and exclusion of other causes of liver injury), and does not account for contraindications to treatment. Prothrombin time and bilirubin values can vary between labs and testing methods, so small differences in DF near the 32-point cutoff should not be over-interpreted. Always discuss results, and any treatment decision, with a hepatologist or gastroenterologist.