Life-threatening drug-associated hyperkalemia: a retrospective study from laboratory signals.

Purpose: Life-threatening hyperkalemia may be induced by drugs and preventable in at-risk patients. This study was designed to describe cases of 'serious' drug-associated hyperkalemia.

Methods: Adult subjects with a serum potassium concentration above 6.5 mmol/L detected at admission or during hospital stay in nephrology, cardiology, geriatric, emergency or intensive care units were identified by biology laboratories of hospitals and clinics located in Midi-Pyrenees (southwest France). Patients dialyzed for end-stage kidney disease were excluded. Data were collected from medical files. Hyperkalemia was defined as drug-associated if at least one drug known to increase serum potassium concentration was taken when hyperkalemia occurred (among drugs taken in outpatient care for hyperkalemia detected at admission and among drugs taken in outpatient care and continued at hospital and drugs introduced from admission for hyperkalemia detected during hospital stay).

Results: Of 168 hyperkalemia cases, 102 (60.7%) were classified as drug-associated. They concerned elderly patients (mean age: 76.1 years) often having arterial hypertension and/or cardiac diseases (88.2%). Risk factors, mainly acute kidney failure, were observed in almost all cases (98.0%). Drugs predominantly involved were angiotensin-converting enzyme inhibitors (47.1%), spironolactone (41.2%), angiotensin II receptor antagonists (23.5%) and potassium supplements (23.5%). In 10% of cases, death could be attributed to hyperkalemia.

Conclusions: Laboratory databases allowed an exhaustive identification of hyperkalemia cases. The frequency of drug-related hyperkalemia and their characteristics suggest that treatment with drugs known to increase serum potassium concentration can be inappropriate, especially regarding associations or indications, and is highly risky for predisposed patients.