Patients with high serum sodium levels prior to kidney transplantation (KT) are at increased risk for death, investigators reported at the National Kidney Foundation’s 2022 Spring Clinical Meetings in Boston, Massachusetts.
In the TC-CKD (Transition of Care in Chronic Kidney Disease) study, 102,477 US veterans with advanced CKD transitioning to kidney replacement therapy were categorized by their 6-month pre-KT serum sodium levels into 5 groups: less than 135, 135-137, 137-140 (reference), 140-143, and 143 mmol/L or higher.
In a subset of 1220 patients who underwent KT, 107 died within a median 2.35 years. Results showed a positive association between corrected serum sodium levels and all-cause mortality, but the association was a J-shape curve, with the lowest risk in the reference group, Ekamol Tantisattamo, MD, MPH, of the University of California, Irvine, and colleagues reported. The risk for all-cause mortality was increased by a significant 2.6-fold among patients with the highest levels of uncorrected serum sodium and by a nonsignificant 2.2-fold among patients with the highest corrected serum sodium levels compared with the reference.
For every 1 mmol/L increase in serum sodium, the risk for all-cause mortality increased 7.48% among patients with a pre-KT corrected serum sodium level of 138 mmol/L or more, but only 0.02% among patients with a pre-KT corrected serum sodium level of less than 138 mmol/L.
Cardiovascular and infectious mortality did not differ among groups. Death-censored and all-cause graft loss also did not differ.
Hospital length of stay significantly decreased 0.47 and 0.38 days for every 1 mmol/L increase in corrected and uncorrected serum sodium level, even after adjusting for non-immunological and immunological factors that can contribute to delayed graft function.
“Although uncommon, either receiving high sodium concentration in the dialysate or lack of free water access may cause hypernatremia in this population,” Dr Tantisattamo told Renal Urology News. He noted that the mechanism by which pre-transplant hypernatremia leads to post-transplant mortality is currently unknown. “It’s possible that hypernatremia may be an independent risk for post-transplant mortality rather than a marker of underlying medical comorbidities.”
Serum sodium levels may be a useful biomarker for predicting post-KT outcomes and may lead to intervention, he concluded.
Tantisattamo E, Streja E, Park C, Wenziger C, Hsiung JT, Segev D, Kalantar-Zadeh K. Association between pre-kidney transplant serum sodium and post-transplant outcomes. Presented at the National Kidney Foundation’s 2022 Spring Clinical Meetings, Boston, Massachusetts, April 6-10, 2022. Poster 421.