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Discriminant Function (DF) Calculator

Discriminant Function (DF) for Alcoholic Hepatitis

Understanding the Discriminant Function

The Discriminant Function (DF), also known as the Maddrey's Discriminant Function, is a scoring system used to assess the severity of alcoholic hepatitis. It helps clinicians determine which patients might benefit from corticosteroid therapy. The score is particularly important because it helps identify patients with severe disease who have a poor prognosis without treatment.

What is the Discriminant Function?

The Discriminant Function (DF), also known as the Maddrey's Discriminant Function, combines two key laboratory values:

  • Prothrombin time
  • Serum bilirubin

The formula is: DF = 4.6 × (PT - control time) + (serum bilirubin / 17.1)

Where:

  • PT is the patient's prothrombin time in seconds
  • Control time is the laboratory's normal prothrombin time in seconds
  • Serum bilirubin is measured in μmol/L

If serum bilirubin is measured in mg/dL, use this simpler formula: DF = 4.6 × (PT - control time) + serum bilirubin

Interpretation of Results

Severity Classification

  • DF ≥ 32: Severe alcoholic hepatitis

    • Strong indication for corticosteroid therapy
    • Higher risk of mortality (up to 35% in 28 days without treatment)
    • Close monitoring required
    • Treatment reduces 28-day mortality to approximately 6%
  • DF < 32: Not severe

    • Supportive care usually sufficient
    • Better prognosis
    • Monitor for progression

Clinical Applications

The DF score is used to:

  1. Assess disease severity
  2. Guide treatment decisions
  3. Predict short-term prognosis
  4. Determine need for corticosteroid therapy

Important Considerations

When to Calculate DF

  • Suspected alcoholic hepatitis
  • Recent heavy alcohol use
  • Elevated liver enzymes
  • Jaundice
  • Clinical deterioration

Limitations

  • Should not be used in isolation
  • Other factors affect prognosis
  • May need serial measurements
  • Consider other scoring systems

Treatment Implications

Severe Disease (DF ≥ 32)

Important exclusions for corticosteroid therapy:

  • Active infection requiring treatment
  • Gastrointestinal bleeding requiring transfusions
  • Acute pancreatitis
  • Chronic renal disease (creatinine > 175 μmol/L)

Not Severe (DF < 32)

  • Supportive care
  • Alcohol cessation
  • Nutritional support
  • Monitor for progression

Tips for Accurate Results

  1. Use current laboratory values
  2. Ensure correct units
  3. Use laboratory-specific control times
  4. Consider trending values

Risk Factors

Factors that may influence prognosis:

  • Age
  • Nutritional status
  • Concurrent infections
  • Renal function
  • Continued alcohol use

Prevention and Management

Key strategies include:

  1. Complete alcohol cessation
  2. Nutritional support
  3. Infection prevention
  4. Regular monitoring
  5. Early intervention

When to Seek Medical Attention

Immediate medical attention needed for:

  • Severe jaundice
  • Confusion
  • Bleeding
  • Fever
  • Severe abdominal pain

Start calculating now to assess alcoholic hepatitis severity!

References:

  1. Carithers RL Jr, et al. Methylprednisolone therapy in patients with severe alcoholic hepatitis. Ann Intern Med. 1989;110(9):685-690.