Clinical Overview: The MELD Score
The Model for End-Stage Liver Disease (MELD) score is a vital prognostic system used to assess the severity of chronic liver disease. Originally developed to predict mortality within three months of surgery in patients who had undergone a TIPS procedure, it proved so accurate that the United Network for Organ Sharing (UNOS) adopted it as the definitive metric for prioritizing liver transplant allocation in adults.
The principle is simple but profound: the sickest patients—those with the highest mathematical probability of short-term mortality—are placed at the top of the transplant list.
Pathophysiology and Lab Values
The MELD score relies exclusively on objective, reproducible laboratory values, completely eliminating subjective clinical assessments (like the degree of ascites used in the older Child-Pugh score).
- Bilirubin: Measures the liver's ability to excrete bile. High levels indicate severe hepatic dysfunction and cause jaundice.
- INR (Prothrombin Time): Measures the liver's ability to synthesize critical blood-clotting proteins.
- Creatinine: Measures kidney function. Because hepatorenal syndrome (kidney failure driven by severe liver disease) is a massive predictor of mortality, renal function is heavily weighted.
- Sodium (MELD-Na): In 2016, serum sodium was added to the official UNOS formula. Hyponatremia (low sodium) in liver disease reflects severe fluid overload and hemodynamic instability.
Formula Breakdown
The original MELD formula uses natural logarithms to weight the laboratory inputs:
MELD = 3.78×ln[Bilirubin] + 11.2×ln[INR] + 9.57×ln[Creatinine] + 6.43
Scores range from 6 (less ill) to 40 (gravely ill). Patients with a MELD score above 30 have a 90-day mortality risk exceeding 50% without a transplant.
Disclaimer: This tool calculates the classic MELD and estimated MELD-Na for educational purposes. UNOS uses highly specific exception points (e.g., for hepatocellular carcinoma) that alter a patient's actual priority on the waitlist. Consult your hepatology team for precise waitlist status.