Prevalence and factors associated with hyperkalemia in predialysis patients followed in a low-clearance clinic.

BACKGROUND AND OBJECTIVES: Recent studies evaluated the prevalence of hyperkalemia and related risk factors in patients with CKD of various stages, but there is limited relevant information in predialysis patients. This study aimed to examine the prevalence and factors associated with hyperkalemia in the structured environment of a low-clearance clinic.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: In a cross-sectional fashion over a prespecified period of 4 months, information on serum potassium and relevant laboratory variables, comorbidities, medications, and dietician input in patients with advanced CKD under follow-up in the low-clearance clinic of our department was recorded. Univariate and multiple logistic regression analyses were used to identify factors associated with serum potassium ≥ 5.5 meq/L.

RESULTS: The study population consisted of 238 patients aged 66.2 ± 4.2 years with estimated GFR of 14.5 ± 4.8 ml/min per 1.73 m(2). The prevalence of hyperkalemia. defined as potassium > 5.0, ≥ 5.5, and ≥ 6.0 meq/L., was at 54.2%, 31.5%, and 8.4%, respectively. In univariate comparisons, patients with potassium ≥ 5.5 meq/L had significantly higher urea and lower estimated GFR and serum bicarbonate; also, they were more often using sodium bicarbonate and had received potassium education and attempts for dietary potassium lowering. Use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers was not associated with hyperkalemia. In multivariate analyses, estimated GFR<15 ml/min per 1.73 m(2) and sodium bicarbonate use were independently associated with hyperkalemia.

CONCLUSIONS: The prevalence of hyperkalemia in predialysis patients with CKD is high. Even at this range of renal function, low estimated GFR seems to be the most important factor associated with hyperkalemia among the wide range of demographic, clinical, and laboratory characteristics studied.