Background Hyperkalaemia is an elevated serum potassium level above 5.5 mmol/L. It can be due to an increased intake, redistribution or decreased renal excretion of potassium. Very high levels of potassium are a medical emergency because of the risk of cardiac arrhythmias.

Purpose To analyse treatment that may cause hyperkalaemia in in-patients.

To evaluate the percentage acceptance of hyperkalaemia recommendations made by the clinical pharmacist.

Materials and methods A descriptive, retrospective study of 6 months in which we reviewed the prescriptions of patients with potassium serum levels ≥5.5 mmol/L using the electronic medical record (Archinet). Variables collected: age, sex, weight, serum creatinine and drugs.

Results 1,500 determinations of potassium serum were read. 4.6% (70/1500) had a value ≥5.5 mmol/L. These 70 measurements belonged to 50 different patients (35 women and 25 men). The average age was 85 years (58–102). The creatinine clearance was ≥60 mL/min for 5/88 determinations, 30–59 mL/min for 25/88 determinations and ≤23 mL/min for 40/88. All the patients were being treated with drugs associated with hyperkalaemia, except one patient.

140 suspected drugs were identified that might have caused the problem: LMWH 46.4%, 14.6% ACE inhibitors, digoxin 10.6%, 7.3% potassium-sparing diuretics, 5.3% parenteral potassium, 4.1% other drugs. 28 recommendations were made to optimise the treatment but only in 14 cases was the suggestion accepted. The proposals included recommendations for reducing a dose, discontinuing drugs known to cause hyperkalaemia, and proposals for monitoring drugs suspected of causing hyperkalaemia.

Conclusions Many commonly-used drugs can cause hyperkalaemia.

Renal function is impaired in the majority of patients with drug-induced hyperkalaemia.

The pharmacy department shall systematically review the potassium serum levels in in-patients and make recommendations.

In our study, the degree of acceptance of the recommendations was moderate.

No conflict of interest.