MELD-Na Calculator

Background.

In a person with cirrhosis, a falling serum sodium is a bad sign. Kim and colleagues showed in 2008, among adults on the US liver-transplant waiting list, that low sodium predicted death on the list over and above the MELD score, and the sodium-adjusted score that came out of that work, MELD-Na, was used to rank adult candidates for deceased-donor livers in the United States from 2016 until MELD 3.0 replaced it in 2023.

The score is built in two stages. Classic MELD combines the natural logarithms of serum bilirubin, INR and serum creatinine: 3.78 ln(bilirubin) + 11.2 ln(INR) + 9.57 ln(creatinine) + 6.43. The sodium step then adds points as sodium falls from 137 towards 125 mmol/L, with the size of the addition shrinking as MELD rises. For bilirubin 3.2 mg/dL, INR 1.8, creatinine 1.4 mg/dL and sodium 130 mmol/L, the formula gives 20.63, which is rounded to a MELD(i) of 21, and MELD-Na is 25.39, reported as 25.

The standard adjustments are applied before the arithmetic and shown with the result: bilirubin, INR and creatinine below 1.0 are raised to 1.0, creatinine above 4.0 is capped at 4.0, creatinine is set to 4.0 after dialysis at least twice, or 24 hours of continuous veno-venous haemodialysis (CVVHD), in the past week, and sodium is held between 125 and 137. As in the OPTN rules, the initial score, MELD(i), is rounded to a whole number and capped at 40, and the sodium step is applied only when MELD(i) is above 11.

The result is the classic formula, worked through openly. It is not the score a transplant programme submits today, it was derived in adults, with children under 12 assessed by PELD instead, and it supports rather than replaces the judgement of the clinicians who know the patient.

What is meld-na calculator?

MELD-Na is a severity score for chronic liver disease, built on the Model for End-Stage Liver Disease. MELD was developed by Kamath and colleagues in 2001 to predict short-term survival and was adopted for US liver allocation in 2002; its three laboratory values reflect bilirubin clearance, the liver's production of clotting factors (INR) and kidney function (creatinine), which often fails in advanced cirrhosis. MELD-Na adds serum sodium, because low sodium in cirrhosis usually reflects severe circulatory disturbance and carries risk the original three values miss. Higher scores mean greater short-term risk. The score says nothing about the cause of the liver disease or the right treatment.

How to use this calculator.

1. 01Enter serum bilirubin in mg/dL. If your laboratory reports µmol/L, divide by 17.1; 54.7 µmol/L is about 3.2 mg/dL.
2. 02Enter the INR from the same set of bloods. The score assumes the INR reflects the liver's own clotting factors, so a value raised by warfarin or another anticoagulant overstates it.
3. 03Enter serum creatinine in mg/dL (µmol/L ÷ 88.4) and serum sodium in mmol/L, which is the same number as mEq/L.
4. 04Switch on the dialysis toggle if the patient had dialysis at least twice in the past seven days, or 24 hours of continuous veno-venous haemodialysis (CVVHD) in that week. Both count the same way.
5. 05Read the rounded MELD-Na, then check the values used, MELD(i) and the sodium delta to see where the score comes from.

The formula.

First the inputs are made safe for logarithms. Bilirubin, INR and creatinine below 1.0 are set to 1.0, because the logarithm of a number below 1 is negative and would lower the score for a normal result. Creatinine is capped at 4.0 mg/dL, and set to 4.0 outright when the dialysis toggle is on (two or more dialysis treatments, or 24 hours of CVVHD, in the past week), so a patient whose creatinine is held down by dialysis still scores as having failed kidneys.

Classic MELD = 3.78 ln(bilirubin) + 11.2 ln(INR) + 9.57 ln(creatinine) + 6.43, using natural logarithms. Because the logs grow slowly, doubling any one value adds a fixed amount: 2.62 points for bilirubin, 7.76 for INR and 6.63 for creatinine.

The unrounded result is rounded to a whole number and capped at 40 to give MELD(i), the initial score, as the OPTN policy specifies. The sodium step is then applied only when MELD(i) is above 11; at 11 or below, MELD-Na is simply MELD(i).

Sodium is held between 125 and 137 mmol/L, and ΔNa = 137 − sodium, from 0 to 12. Then MELD-Na = MELD(i) + 1.32 × ΔNa − 0.033 × MELD(i) × ΔNa. Each mmol/L of sodium below 137 adds 1.32 − 0.033 × MELD(i) points, so low sodium counts for most when MELD(i) is low. At MELD(i) 12, sodium of 125 raises the score to 23.09; at MELD(i) 30 it raises it only to 33.96. At MELD(i) 40 the sodium term is zero, and the final score is capped at 40, so it cannot rise above the maximum. The result is shown both before and after rounding to the nearest whole number.

A calculator that applies the sodium step at every MELD value would give 22 for an initial MELD of 10 with sodium 125 (10 + 15.84 − 3.96 = 21.88). Under the OPTN rule used here the score stays at 10, because MELD(i) is not above 11.

A worked example.

Frequently asked questions.

References& sources.

1. [1]Kim, W. R., et al. (2008). Hyponatremia and mortality among patients on the liver-transplant waiting list. New England Journal of Medicine.
2. [2]Kim, W. R., et al. (2008). Hyponatremia and Mortality among Patients on the Liver-Transplant Waiting List (PMC full text).
3. [3]Biggins, S. W., et al. (2006). Evidence-based incorporation of serum sodium concentration into MELD. Gastroenterology.
4. [4]Kamath, P. S., et al. (2001). A model to predict survival in patients with end-stage liver disease. Hepatology.
5. [5]Wiesner, R., et al. (2003). Model for end-stage liver disease (MELD) and allocation of donor livers. Gastroenterology.
6. [6]Health Resources and Services Administration (2025). Allocation Calculators. OPTN.
7. [7]Health Resources and Services Administration. Questions and Answers About Liver Allocation. OPTN.