What is the difference between MELD and MELD-Na?

MELD uses creatinine, bilirubin, and INR. MELD-Na adds serum sodium, because low sodium independently predicts worse outcomes in cirrhosis. MELD-Na is now the standard for transplant allocation in most regions because it better discriminates mortality risk.

Why are values floored to 1.0?

The formula takes the natural logarithm of each lab value, and the log of a number below 1 is negative, which would distort the score. UNOS rules therefore set any value under 1.0 to 1.0 before the calculation, and cap creatinine at 4.0 mg/dL.

What does the dialysis checkbox do?

If a patient had two or more dialysis sessions in the prior week, or 24 hours of continuous haemodialysis, their creatinine is set to 4.0 mg/dL regardless of the measured value. This reflects that dialysis masks true renal function.

What mortality does a given MELD score predict?

Roughly, a score of 9 or below carries about 2 percent 90-day mortality, 10 to 19 about 6 percent, 20 to 29 about 20 percent, 30 to 39 about 50 percent, and 40 about 70 percent. These are population estimates and vary by cause of liver disease.

Yes. The reported MELD and MELD-Na are bounded between 6 and 40. A score of 40 is the maximum used for allocation, representing the most urgent transplant priority.

MELD & MELD-Na Score Calculator

The Model for End-Stage Liver Disease (MELD) turns three routine lab values into a single number that predicts short-term mortality in advanced liver disease. Because it is objective and reproducible, it became the basis for ranking patients on transplant waiting lists, later refined with serum sodium as MELD-Na.

How it works

The original MELD is a weighted sum of the natural logs of three labs:

MELD = 0.957 x ln(creatinine)
     + 0.378 x ln(bilirubin)
     + 1.120 x ln(INR)
     + 0.643
MELD = round(MELD x 10)

Before the logs are taken, any value below 1.0 is set to 1.0, creatinine is capped at 4.0 mg/dL, and dialysis forces creatinine to 4.0. The result is bounded between 6 and 40.

The sodium correction is applied when MELD is 12 or higher:

MELD-Na = MELD + 1.32 x (137 - Na)
          - 0.033 x MELD x (137 - Na)

with sodium clamped to the range 125 to 137 mEq/L.

Example and notes

A patient with creatinine 1.9, bilirubin 4.0, and INR 1.8 produces a MELD in the high teens; adding a low sodium of 128 pushes MELD-Na several points higher, reflecting the worse prognosis of hyponatraemia. The score is a prognostic estimate, not a treatment decision, and should always be interpreted alongside the clinical picture and local allocation policy.