MELD Na Score Calculator

How does this MELD Na score calculator work?

This health tool assesses the outcome in patients who need transplant or suffer from a serious liver condition such as cirrhosis and adds the serum sodium determination to the precedent equation in the Model of End Stage Liver Disease.

This MELD-Na score calculator differs from the standard MELD calculator because it uses the Na value to adapt the result and to provide a more specialized view and improves upon the MELD Score for liver cirrhosis, especially in regard to the mortality prediction.

This model evaluation is used in patients in which cirrhosis is caused by factors that are not reversible and transplant is the only solution. The sodium addition in the model was based on the registration data from the United Network for Organ Sharing. The formula used is the one below and sodium normal values are around 135 mEq/L.

MELD Na = MELD − Na − [0.025 × MELD × (140 − Na)] + 140

Serum sodium is often used as a marker for the severity of a disease, especially in cirrhosis where hyponatremia indicates solute-free water retention and the indirect marker of portal hypertension during cirrhosis.

Hyponatremia is in general considered a predictor of early mortality, therefore independent of the previous MELD score but now more specific and superior to the original model for patients awaiting transplant.

Survival chances change significantly, especially in the ranges of sodium change between 120 and 135 mEq/L, when a decrease in serum sodium of one unit corresponds to a 12% increase in mortality risk in the following 3 months.

The only criticism received by the model concerns the fact that it doesn’t have yet enough relevant validation. As sodium changes in cirrhosis might be due to some other factors, not necessarily related to the severity of the condition itself or the liver damage, such as diuretic use or intravenous administration of hypotonic fluids, the model should account for this in a better proportion.

The other variables remain the same as in the original Model of End Stage Liver Disease Calculator formula, including:

MELD Score = 10 * [(0.957 x ln(Creatinine)) + (0.378 x ln(Bilirubin)) + (1.12 x ln(INR))] + 6.43

■ INR – with the highest weight but sometimes hard to interpret in patients receiving anticoagulation therapy along due to the existence of portal vein thrombosis.

■ Serum Bilirubin – a great prognostic indicator about the ability of the liver to fulfill its function.

■ Serum Creatinine – with an upper limit of 4 mg/dL and an adjustment in case the patient is on dialysis at the moment of the evaluation.

MELD Na interpretation

The MELD models are basically a severity index by the United Network for Organ Sharing (UNOS) that allows a prioritization of organ transplant by showing the mortality risk in severe cirrhosis cases. The commonly met score range is usually between 6 and 40 but extremes can become apparent. The 3 month mortality prediction as per the MELD definition in regard to waiting list mortality is listed below:

■ MELD score >40: 71.3% mortality.

■ MELD score 30–39: 52.6% mortality.

■ MELD score 20–29: 19.6% mortality.

■ MELD score 10–19: 6.0% mortality.

■ MELD score <9: 1.9% mortality.

References

1) Kim WR, Biggins SW, Kremers WK, Wiesner RH, Kamath PS, Benson JT, Edwards E, Therneau TM. (2008) Hyponatremia and mortality among patients on the liver-transplant waiting list. N Engl J Med; 359(10):1018-26.

2) Biggins SW, Kim WR, Terrault NA, Saab S, Balan V, Schiano T, Benson J, Therneau T, Kremers W, Wiesner R, Kamath P, Klintmalm G. (2006) Evidence-based incorporation of serum sodium concentration into MELD. Gastroenterology; 130(6):1652-60.

3) Wong VW, Chim AM, Wong GL, Sung JJ, Chan HL. (2007) Performance of the new MELD-Na score in predicting 3-month and 1-year mortality in Chinese patients with chronic hepatitis B. Liver Transpl; 13(9):1228-35.