Prevalence and factors associated with hyperkalaemia in stable kidney transplant recipients

Hyperkalaemia is a frequent and potentially life-threatening condition in patients with chronic kidney disease (CKD). Even after successful kidney transplantation (KTx), KTx recipients have mild to severe CKD. Moreover, they share comorbid conditions and frequently use medications that predispose to hyperkalaemia. This study aimed to examine the prevalence and factors associated with hyperkalaemia in this population.

Over a pre-specified period of 6 months (1 September 2019 to 31 March 2020), we recorded in cross-sectional fashion information on serum potassium (K⁺) and relevant demographics, comorbidities, medications, laboratory and transplant-associated variables in clinically stable KTx recipients attending the Transplant Outpatient Clinic of our Department. Ηyperkalaemia was classified as follows: serum K⁺ level >5.0 mEq/L; and further as >5.0 mEq/L with concomitant use of sodium (Na⁺) polystyrene sulphonate; serum K⁺ ≥5.2 mEq/L; serum K⁺ ≥5.5 mEq/L. Univariate and multiple logistic regression analyses were used to identify factors associated with serum K⁺ >5.0 mEq/L.

The study population consisted of 582 stable KTx recipients, 369 (63.4%) males, aged 52.4 ± 13.5 years, with estimated glomerular filtration rate (eGFR) of 55.8 ± 20.1 mL/min/1.73 m² transplanted for >1 year. The prevalence of hyperkalaemia defined as K⁺ >5.0 mEq/L; >5.0 mEq/L and use of Na⁺ polystyrene sulphonate; K⁺ ≥5.2; or K⁺ ≥5.5 mEq/L, was: 22.7, 22.7, 14.4 and 4.1% (132, 132, 84 and 24 patients), respectively. In multivariate analysis, male gender [odds ratio (OR) = 2.020, 95% confidence interval (CI) 1.264-3.227] and use of renin-angiotensin-aldosterone system (RAAS) blockers (OR = 1.628, 95% CI 1.045-2.536) were independently associated with hyperkalaemia, while higher eGFR (OR = 0.967, 95% CI 0.955-0.979) and use of non-K⁺-sparing diuretics (OR = 0.140, 95% CI 0.046-0.430) were associated with lower odds of the disorder.

The prevalence of mild hyperkalaemia in stable KTx recipients is relatively high but that of moderate or severe hyperkalaemia is low. Among a wide range of factors studied, only male gender and RAAS blockade were associated with increased odds of hyperkalaemia, while higher eGFR and diuretics were associated with decreased odds of hyperkalaemia.