Association of serum potassium with decline in residual kidney function in incident hemodialysis patients

Background Hyperkalemia is associated with kidney function decline in patients with non-dialysis dependent chronic kidney disease, but this relationship is unclear for residual kidney function (RKF) among hemodialysis (HD) patients. Methods We conducted a retrospective cohort study of 6655 patients, who started HD January 2007 and December 2011 and who had data on renal urea clearance (KRU). Serum potassium levels were stratified into four groups (i.e. <= 4.0, >4.0 to <= 4.5, >4.5 to <= 5.0 and >5.0 mEq/L) and 1-year KRU slope for each group was estimated by a linear mixed-effects model. Results Higher serum potassium was associated with a greater decline in KRU, and the greatest decrease in KRU (-0.20, 95% confidence interval -0.50 to -0.06) was observed for baseline potassium >5.0 mEq/L in the fully adjusted model. Mediation analysis showed that KRU slope mediated 1.78% of the association between serum potassium and mortality. Conclusions Hyperkalemia is associated with a decline in RKF amongst incident HD patients. These findings may have important clinical implications in the management of hyperkalemia in advanced CKD if confirmed in additional clinical trials.