Maddrey Discriminant Function Calculator

Maddrey Discriminant Function Calculator for Gastroenterology. Exactly 32 is included in the historical high-DF group. Neither crossing this threshold nor staying below it establishes a diagnosis or determines benefit, harm or eligibility for corticosteroids.

For shared guidance on choosing a tool and documenting results, read the clinical calculator workflow.

How this calculator works

Modified Maddrey DF = 4.6 x (patient PT - laboratory control PT) + bilirubin in mg/dL. Use PT in seconds, not INR. Exactly 32 belongs to the historical severe-risk threshold group.

When to use this calculator

Use only in a clinician-established alcohol-associated hepatitis assessment. DF is a historical severity measure, not a diagnostic test for that condition or a stand-alone prescription rule.

Inputs used

  • Patient PT (seconds)
  • Laboratory control PT (seconds)
  • Bilirubin (mg/dL)

Clinical interpretation

Exactly 32 is included in the historical high-DF group. Neither crossing this threshold nor staying below it establishes a diagnosis or determines benefit, harm or eligibility for corticosteroids.

Worked example

Fictional teaching case. Patient PT (seconds): 22; Laboratory control PT (seconds): 12; Bilirubin (mg/dL): 15. Result: 61. At or above historical DF 32 threshold. DF does not diagnose alcohol-associated hepatitis or determine steroid eligibility. Review the diagnosis, contraindications and current specialist pathway.

Limitations and safety notes

Laboratory PT calibration affects the result. DF below 32 does not prove steroid harm, and DF at least 32 does not automatically justify treatment.

Frequently asked questions

Can I enter INR instead of control PT?

No. Use the required PT measurements and the corresponding laboratory control, or choose a different model designed for INR.

What can change the meaning of this result?

Laboratory PT calibration affects the result. DF below 32 does not prove steroid harm, and DF at least 32 does not automatically justify treatment.

References

  • Randomized trial gives modified DF equation and bilirubin conversion. https://pubmed.ncbi.nlm.nih.gov/2648927/
  • ACG 2024 alcohol-associated liver disease guidance; treatment eligibility is multifactorial. https://pmc.ncbi.nlm.nih.gov/articles/PMC11040545/

Editorial review and citation methodology

Maintained by the Quick Medical Calculator Editorial Team. Content record date: September 9, 2026. A content date is not evidence of independent clinical review. Individual clinical sign-off is not recorded on this page.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

Related reviewed calculators