Hyperkalemia in hospitalized patients.

OBJECTIVE: Evaluate the prevalence of hyperkalemia (potassium > 5.5 mmol/l) in hospitalized patients not on dialysis, as well as the association of medications, impaired renal function and comorbid conditions with hyperkalemia.
DESIGN: A retrospective case-control method.
SETTING: A tertiary care teaching hospital. PATIENTS: Hyperkalemic adults not on dialysis with age and sex matched controls.
INTERVENTIONS: None. MAIN OUTCOME MEASURES: The use of medications associated with hyperkalemia and renal function using a calculated creatinine clearance were compared in the hyperkalemic and control groups.
RESULTS: 35 adult patients with hyperkalemia who were not receiving dialysis were identified, with a prevalence in the hospitalized population of 3.3%. The hyperkalemic patients were older than the general hospital population (p < 0.05). Compared with controls, hyperkalemic patients: had a lower creatinine clearance (p < 0.05), were more likely to be taking angiotensin-converting enzyme inhibitors (p < 0.05), and had an increased frequency of diabetes mellitus (p < 0.001). All of the control patients survived their hospitalization, but the mortality rate in the hyperkalemic group was 17% (p < 0.0001). None of the deaths were directly attributable to hyperkalemia.
CONCLUSIONS: Hyperkalemia is more frequent in older patients and is usually mild. Hyperkalemia is associated with diabetes mellitus, diminished renal function and the use of angiotensin-converting enzyme inhibitors. An elevated serum potassium level in a hospitalized patient may be a marker for a significantly increased risk of death, which is due to underlying medical problems and is not a consequence of the hyperkalemia.