In patients with advanced chronic kidney disease (CKD) transitioning to dialysis, having serum potassium levels in the high-normal range may yield better long-term survival, investigators reported during Kidney Week 2020 Reimagined, the virtual conference sponsored by the American Society of Nephrology.

Laboratories have defined a wide reference range of at least 3.5 but less than 5.5 mEq/L for “normal” serum potassium levels. However, in a study of 43,798 mostly male US veterans transitioning to end-stage kidney disease (mean age 69 years; 29% Black race), high-normal serum potassium levels of at least 5.0 but less than 5.5 mEq/L were associated with 5% greater survival after dialysis initiation compared with a reference of at least 4.5 but less than 5.0 mEq/L, as reported by the study’s first-author, Yoko Narasaki, RD, PhD, senior-author, Connie M Rhee, MD, MSc, of the University of California, Irvine, and colleagues. In contrast, low-normal serum potassium concentrations of at least 4.0 but less than 4.5 mEq/L and at least 3.5 but less than 4.0 mEq/L and below-normal levels of less than 3.5 mEq/L were associated with 7%, 5%, and 16% higher risks for all-cause mortality, respectively. The team adjusted for differences in demographics, body mass index, coronary artery disease, Charlson Comorbidity Index, and systolic blood pressure.

“Further studies are needed to determine whether dietary factors may be a potential mechanistic link underlying these relationships,” Dr Narasaki and Dr Rhee’s team stated. “While dietary potassium is commonly restricted in patients with CKD to mitigate hyperkalemia, there may be ill effects from a strategy that restricts healthy, potassium-rich foods, such as fruits and vegetables.”

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Narasaki Y, Kalantar-Zadeh K, Ferrey AJ, et al. Serum potassium and survival among advanced CKD patients transitioning to dialysis. Presented at: Kidney Week 2020 Reimagined, October 19-25, 2020. Poster PO0480.