Low Sodium Levels Increase Liver Transplant Survival Benefit

Low sodium levels in the blood, otherwise known as hyponatremia, can increase the risk of dying for patients on a liver transplant waiting list.

Recent findings published in Liver Transplantation show that survival chances are increased when patients with hyponatremia and a Model for End Stage Liver Disease (MELD) score of 12 or more.

The MELD score helps to measure the risk of death on the waiting list by calculating a patient's serum bilirubin, creatinine, and prothrombin time and is used by national organ allocation policy to determine the priority for a patient on the transplant waitlist. For instance, those who are the most sick with a high MELD score are at the top of the waitlist.

Previous research links low serum sodium, in combination with the MELD score, to increased waitlist mortality, prompting Organ and Procurement Transplant Network (OPTN) directors to approve a new policy that gives additional MELD score points (1 to 13 based on serum sodium value) to patients with hyponatremia.

"While the OPTN serum sodium allocation formula may reduce deaths on the waitlist by enhancing access to donor organs, it is not clear if candidates with hyponatremia gain any survival benefit over patients with normal sodium levels," said lead study author Dr. Pratima Sharma, with University of Michigan Health System in Ann Arbor , in a news release. "Our study examines if patients with low serum sodium prior to liver transplant have a greater survival benefit than patients without low serum sodium, all other things being equal."

For the study, researchers used data from the Scientific Registry of Transplant Receipients, which identified 69,213 candidates, 18 years of age or older that were on the wait list for liver transplants between January 2005 and December 2015. All participants were matched to waitlist candidates with the same MELD score and located in the same donation service area.

"Our results suggest that adjustment based on serum sodium for the purpose of the liver allocation process should be considered for those candidates with low sodium levels and a MELD score of at least 12. Health care providers should also alert liver transplant patients on the waiting list that low sodium levels could increase their mortality risk on the waitlist and may affect the expected survival benefit following liver transplantation."

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