Clinical

Hyponatremia linked to mortality in liver transplantation candidates

Last Updated: 2008-09-03 17:00:22 -0400 (Reuters Health)

By Anthony J. Brown, MD

NEW YORK (Reuters Health) - Hyponatremia is a significant risk factor for death in patients on the liver-transplant waiting list, according to a report in the September 4th issue of The New England Journal of Medicine.

The results suggest that the predictive value of the Model for End-Stage Liver Disease (MELD) scoring system, which is used to allocate donated livers, can be enhanced through combination with the serum sodium level (MELDNa).

"In patients with a severely low sodium level, their risk of mortality increases substantially," lead author Dr. W. Ray Kim, from the Mayo Clinic College of Medicine in Rochester, Minnesota, told Reuters Health. "However, as the number of such patients is relatively small, this was not apparent in previous studies with a smaller sample size."

The new findings stem from an analysis of data from adult liver transplantation candidates registered with the Organ Procurement and Transplantation Network in 2005.

The focus of the study was to assess the predictive ability of the MELD score alone or combined with the serum sodium level. The MELD score, which ranges from 6 to 40 (higher equals worse disease), is calculated based on serum bilirubin and creatinine levels and on the INR for the prothrombin time.

Overall, 6769 registrants were identified, including 1781 who received a liver transplant and 422 who died within 90 days of registration on the waiting list.

The MELD score and the serum sodium level were both significant predictors of mortality. For each 1-point increase in MELD, the odds of death rose by 21%, while each 1-unit drop sodium levels from 125 to 140 mmol/L raised mortality by 5%.

The impact of hyponatremia on death was increased in subjects with a low MELD score, the report indicates.

Applying these findings to prior data, the authors found that the MELD score plus sodium level was better than the MELD score alone in predicting death. Had this combined predictive test been employed, the team believes that transplantation would have occurred and prevented death in many patients.

"The study by Kim and colleagues is a benchmark in quantifying the risk of death among patients with cirrhosis," Drs. Andres Cardenas and Pere Gines, from the University of Barcelona, write in a related editorial.

"The possibility that this new MELDNa scoring system might reduce mortality among patients on the waiting list needs to be evaluated and validated in prospective studies that take into account not only mortality among patients on the waiting list but also the outcomes after liver transplantation."

N Engl J Med 2008;359:1018-1026,1060-1062.