ACE-inhibitor or AT2-antagonist therapy of renal transplant recipients is associated with an increase in serum potassium concentrations.

BACKGROUND: Angiotensin-converting enzyme inhibitors (ACEI) or angiotensin II type 1 receptor blockers (ARB) are frequently prescribed to renal transplant recipients with a reduced glomerular filtration rate (GFR). The aim of this study was to investigate the association of ACEI/ARB use and serum potassium levels in renal graft recipients.

METHODS: We conducted an open cohort study of 2041 first renal allograft recipients, transplanted at the Medical University of Vienna between 1990 and 2003. Serum potassium levels were compared over an up to 10 years of observation period between subjects with versus without ACEI/ARB therapy using a mixed effects general linear model. The analysis was adjusted for several covariables known to influence serum potassium such as the use of diuretics, beta blockers, calcineurin inhibitor (CNI) based immunosuppression, estimated GFR, time since renal transplantation, diabetes, years on dialysis and recipient age.

RESULTS: The overall adjusted estimated serum potassium difference between recipients with versus without ACEI/ARB therapy was 0.08 mmol/l (P < 0.001). The use of diuretics was associated with a 0.11 mmol/l (P < 0.001) lower potassium concentration whereas each GFR decrease by 10 ml/min led to an increase of 0.04 mmol/l (P < 0.001). CNI intake increased serum potassium by 0.06 mmol/l (P = 0.002). Furthermore, serum potassium increased by 0.17 mmol/l within the first decade after transplantation (P < 0.001) while holding the other covariables constant. No effect modification between ACEI/ARB and time since transplantation was observed. Nineteen subjects (2.4%) discontinued the ACEI/ARB therapy due to hyperkalaemia.

CONCLUSIONS: In summary, relevant hyperkalaemia associated with ACEI/ARB therapy is negligible in renal transplant recipients during long-term follow-up. The hyperkalaemic effect of ACEI/ARB is balanced by the use of diuretics.