Hypokalemia or hyperkalemia at hospital admission increases the chances patients will die within a year, new study results suggest.

Of 73,983 patients, 12.6% died within a year of hospitalization. An admission serum potassium of 4.0 to 4.4 mEq/L was associated with the lowest mortality, Charat Thongprayoon, MD, of Mayo Clinic in Rochester, Minnesota, and collaborators reported in Medicines. Estimated 1-year mortality was 22.6% in the serum potassium group of 2.9 or less; 16.4% in 3.0–3.4; 12.1% in 3.5–3.9; 10.6% in 4.0–4.4; 12.4% in 4.5–4.9; 18.6% in 5.0–5.4; and 25.8% in 5.5 or more mEq/L.

In adjusted analyses, serum potassium levels of 2.9 or less, 3.0–3.4, and 3.5–3.9 mEq/L were significantly associated with a 67%, 36%, and 19% increased risk for 1-year mortality, respectively, compared with a level of 4.0–4.4 mEq/L (referent). Serum potassium levels of 5.0–5.4 and 5.5 mEq/L of higher were significantly associated with 30% and 62% increased risks for 1-year mortality, respectively. The investigators adjusted for age, sex, race, estimated glomerular filtration rate (eGFR), principal diagnosis, comorbidities, medications, acute kidney injury, mechanical ventilation, and other electrolytes. Patients with end-stage renal disease patients were excluded from the study.

Subgroup analyses of patients with chronic kidney disease (CKD) and cardiovascular disease (CVD) yielded results similar to those of the main analysis. In patients with CKD who had an eGFR of less than 60 mL/min/1.73m2, admission serum potassium levels of 2.9 or less, 3.0–3.4, and 3.5–3.9 mEq/L were significantly associated with 94%, 23%, and 22% increased risks for 1-year morality compared with the referent. Serum potassium levels of 5.0–5.4 and 5.5 and more mEq/L were significantly associated with 14% and 32% increased risks.

Among patients with CVD, admission serum potassium levels of 2.9 or less, 3.0–3.4, and 3.5–3.9 mEq/L were significantly associated with 230%, 64%, and 29% increased risks for death. Serum potassium levels of 5.0–5.4 and 5.5 mEq/L or higher were significantly associated with 14% and 47% higher risks.

In both the CKD and CVD groups, the highest mortality risk was found among patients with the lowest and highest serum potassium at admission.

Dyskalemia might increase mortality risk due to the effects of potassium ions on cardiac myocytes leading to arrhythmias, Dr Thongprayoon’s team discussed.

“In line with our research, we suggested that the optimal potassium level among hospitalized patients should be kept between 4.0–5.0 mEq/L to prevent cardiovascular adverse outcomes,” they noted, but more research is clearly needed.

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Reference

Thongprayoon C, Cheungpasitporn W, Hansrivijit P, et al. Admission serum potassium levels in hospitalized patients and one-year mortality. Meds. doi: 10.3390/medicines7010002