MELD-Na Score Calculator
The MELD-Na score estimates the severity of chronic liver disease and is used in prioritising liver transplantation. It builds on the original MELD score (from bilirubin, INR, and creatinine) by adding serum sodium, which improves prediction of short-term mortality. This tool applies the published MELD-Na equation with its standard bounding rules. It is an arithmetic aid; allocation and clinical decisions are not made here.
MELD-Na formula
MELD(i) = 0.957 * ln(creatinine) + 0.378 * ln(bilirubin) + 1.120 * ln(INR) + 0.643
MELD = round(MELD(i) * 10)
If MELD > 11: MELD-Na = MELD + 1.32 * (137 - Na) - (0.033 * MELD * (137 - Na))
Bilirubin and creatinine are in mg/dL, sodium in mmol/L. Per the published rules each of bilirubin, INR, and creatinine is set to a minimum of 1.0 before taking the logarithm, sodium is bounded to the range 125 to 137 mmol/L, and the final score is bounded between 6 and 40. The sodium adjustment applies only when the base MELD exceeds 11.
Worked example
For bilirubin 2 mg/dL, INR 1.5, creatinine 1.2 mg/dL, and sodium 135 mmol/L: MELD(i) = 0.957*ln(1.2) + 0.378*ln(2) + 1.120*ln(1.5) + 0.643 = 0.1745 + 0.2620 + 0.4541 + 0.643 = 1.5336, times 10 and rounded gives 15. Since 15 > 11, MELD-Na = 15 + 1.32*(137-135) - (0.033*15*(137-135)) = 15 + 2.64 - 0.99 = 16.65, rounded to 17.
Frequently asked questions
Why are values floored at 1.0?
The MELD equations take natural logarithms, and ln of a number below 1 is negative. To keep the score behaving sensibly, bilirubin, INR, and creatinine are each set to a minimum of 1.0 before the logarithm, as specified in the published method.
Why bound sodium between 125 and 137?
The MELD-Na derivation bounds sodium to that range so that extreme values do not distort the adjustment. Sodium below 125 is treated as 125 and above 137 as 137.
What score range does MELD-Na use?
The final MELD-Na is bounded between 6 and 40. A higher score reflects greater short-term mortality risk. The clinical and allocation meaning is set by transplant programmes, not by this tool.
Is this used for transplant allocation directly?
Allocation policies are set by organ-sharing authorities and may use specific versions and exceptions. This calculator reproduces the MELD-Na arithmetic for education and is not an allocation system.
Sources
- U.S. Organ Procurement and Transplantation Network (OPTN): OPTN policy resources.
- U.S. National Library of Medicine, StatPearls: Model for End-Stage Liver Disease (MELD).
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. Educational tool, not medical advice. See our methodology.