Inpatient therapy for heart failure can lead to serum potassium disturbances, which appear not to be harmful — but related changes in medication might be, researchers say.

Dutch-led researchers studied data on close to 1600 hospitalised heart-failure patients taking part in a clinical trial. Daily measurements of serum potassium were made from baseline until discharge or day 7 of hospitalisation.

Overall serum potassium concentrations increased significantly, from 4.3mmol/L at baseline to 4.5mmol/L at discharge or day 7. Incident hypokalemia was seen in 17% and incident hyperkalemia in 35% of patients.

Thirty-four patients (2%) had episodes of both hypo- and hyperkalemia.