Analysis of factors causing hyperkalemia

Patients with impaired renal function or diabetes are considered to be prone to hyperkalemia. Furthermore, hyperkalemia is an adverse drug reaction of inhibitors of the renin-angiotensin system (RAS) that are established to be efficacious in these patients. However, the current status of hyperkalemia in the clinical setting remains obscure.

A total of 9,117 patients treated at Toranomon Hospital between January and October 2005, who had serum creatinine levels below 5 mg/dL were studied. Patients on dialysis and patients using cation exchange resin or diuretics that lower serum potassium were excluded.

Serum potassium increased significantly accompanying the increase in serum creatinine, and was significantly elevated in diabetic patients compared to non-diabetic patients. Serum potassium also increased significantly with the administration of angiotensin-II receptor blockers (ARB), angiotensin-converting-enzyme inhibitors (ACEI) or beta-blockers. A combination of diabetes and RAS inhibitor administration significantly increased serum potassium compared to each factor alone in patients with a serum creatinine level below 1.5 mg/dL but not in those with a higher serum creatinine level. According to step-wise multiple regression analyses, an elevated serum creatinine level had the strongest positive correlation with the serum potassium level, followed by diabetes, ACEI use, ARB use, and age.

Lowered renal function, diabetes, use of RAS inhibitors and old age are independent factors that increase the serum potassium level. Caution should be exercised when using RAS inhibitors in diabetic patients even if their renal function is relatively preserved. In selected patients with diabetes or impaired renal function, however, RAS inhibitors can be used without hyperkalemia.