High and low serum potassium levels before hemodialysis (HD) sessions are associated with an increased risk for death, according to a recent prospective study of adult patients new to HD.

Predialysis levels of 4.0 mmol/L or lower and levels higher than 6.0 mmol/L are associated with 1.4- and 1.3-fold increased risks for 6-month all-cause mortality, respectively, in adjusted analyses compared with an optimum level of approximately 5.1 mmol/L, Esther N.M. de Rooij, MD, of Leiden University Medical Center in Leiden, The Netherlands, and colleagues reported in Kidney Medicine.

“If proven causal, the clinical implication of these results is that potassium-lowering therapy should be used with caution in hemodialysis patients with normal or low serum potassium level before the dialysis session,” the investigators reported. “Furthermore, as low predialysis serum potassium could result from malnourishment, the associated mortality risk emphasizes the importance of preventing nutritional disorders in hemodialysis patients.”

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The study included 1117 incident HD patients older than 18 years from the Netherlands Cooperative Study on the Adequacy of Dialysis. Investigators followed patients from their first HD treatment until death, transplantation, switch to peritoneal dialysis, or a maximum of 10 years. They measured predialysis serum potassium every 6 months.

At baseline, the study population had a mean age of 63 years; 58% of patients were men, 26% smoked, 24% had diabetes, and 32% had cardiovascular disease. The mean serum potassium level was 5.0 mmol/L. In addition, 7% had low subjective global assessment scores. The median residual kidney function was 3.5 mL/min/1.73 m2. A total of 555 deaths occurred during 10 years of follow-up.

The authors noted that, to their knowledge, their study is the first to include only incident HD. “All previous studies investigating the relation between predialysis serum potassium and death included mainly prevalent hemodialysis patients, thus being susceptible to survivor bias,” they wrote.


de Rooij ENM, Dekker FW, Cessie SL, et al. Serum potassium and mortality risk in hemodialysis patients: A cohort study. Kidney Med. Published online October 22, 2021. doi:10.1016/j.xkme.2021.08.013