Understanding the MELD Score
The Model for End-Stage Liver Disease (MELD) score is a widely used scoring system to assess the severity of chronic liver disease. It was originally developed to predict mortality within three months of surgery in patients who had undergone a transjugular intrahepatic portosystemic shunt (TIPS) procedure, but it is now the primary tool used by the United Network for Organ Sharing (UNOS) and Eurotransplant for prioritizing patients for liver transplantation.
The MELD and MELD-Na Formulas
The original MELD score relies on three objective laboratory values: serum creatinine (kidney function), serum bilirubin (liver's ability to clear bile), and the International Normalized Ratio (INR, reflecting the liver's ability to produce blood-clotting factors).
MELD = 10 × (0.957 × ln(Creatinine) + 0.378 × ln(Bilirubin) + 1.120 × ln(INR) + 0.643)
In 2016, serum sodium was added to the score to create the MELD-Na score, as low sodium (hyponatremia) is a strong independent predictor of mortality in patients with cirrhosis.
MELD-Na = MELD + 1.32 × (137 − Na) − [0.033 × MELD × (137 − Na)]
Important calculation rules:
- Any value (Creatinine, Bilirubin, INR) less than 1.0 is rounded up to 1.0 to prevent negative scores.
- The maximum value for Creatinine is capped at 4.0 mg/dL.
- If the patient has undergone dialysis twice in the last 7 days, Creatinine is automatically set to 4.0 mg/dL.
- For the MELD-Na calculation, Sodium is clamped between 125 and 137 mEq/L.
Interpreting the Score
MELD scores range from 6 to 40. A higher score indicates more severe liver disease and a higher risk of 90-day mortality without a transplant. Generally:
- < 10: Lower priority for transplant, mild to moderate disease.
- 10 - 19: Moderate priority.
- 20 - 29: High priority.
- 30 - 40: Highest priority, severe disease with high short-term mortality.
Exceptions
Certain conditions, such as hepatocellular carcinoma (liver cancer), hepatopulmonary syndrome, or familial amyloid polyneuropathy, may grant patients "exception points." This means their MELD score is artificially increased to reflect their true mortality risk and improve their chances of receiving a transplant in a timely manner.
When to Consult a Doctor
Liver disease is complex and requires specialized care. If you have been diagnosed with cirrhosis or end-stage liver disease, your MELD score should be regularly monitored by a hepatologist or gastroenterologist.