Study on Potassium Levels in Hemodialysis Patients

Hemodialysis patients rely mainly on potassium removal during each dialysis session as potassium homeostasis is mainly regulated by the kidneys. A recent study suggests that predialysis hyper- and hypokalemia might increase the risk of death. The study findings were published in the journal Kidney Medicine on October 22, 2021.

Predialysis serum potassium is a known modifiable risk factor for death in hemodialysis patients, especially for hypokalemia, this risk may be underestimated. Therefore, Dr. Esther N.M. de Rooij MD and her team investigated the relation between predialysis serum potassium and death in incident hemodialysis patients and whether there is an optimum level.

In a prospective multi-centre cohort study, the researchers included 1117 incident hemodialysis patients (>18y) from the Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD). They evaluated the patients from their first hemodialysis treatment until death, transplantation, switch to peritoneal dialysis or a maximum of 10 years. They examined predialysis serum potassium for every 6 months and divided it into six categories:

• ≤4.0
• >4.0-≤4.5
• >4.5-≤5.0
• >5.0-≤5.5 (reference)
• >5.5-≤6.0
• >6.0 mmol/L

The major outcome assessed was all-cause mortality by 6-month.

Key Findings of the Study

Among 1117 hemodialysis patients, 58% were men, 26% smoked, 24% had diabetes, and 32% had cardiovascular disease.

At baseline, the researchers noted that 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/1.1.73m².

Upon ten year follow-up, they observed 555 (50%) deaths.

For the six potassium categories, they used multivariable adjusted hazard ratios to measure the outcome. Death according to the six potassium categories were: 1.42 (1.01-1.99), 1.09 (0.82-1.45), 1.21 (0.94-1.56), 1 (reference), 0.95 (0.71-1.28) and 1.32 (0.97-1.81).

The authors concluded, "We found a U-shaped relation between serum potassium and death in an incident hemodialysis patients. Low predialysis serum potassium was associated with a 1.4-fold stronger risk of death compared to the optimal level of approximately 5.1 mmol/L".

They further added, "These results may imply cautious use of potassium-lowering therapy and potassium-restricted diet in hemodialysis patients."

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DOI: https://doi.org/10.1016/j.xkme.2021.08.013