[Effect of serum potassium level on renal function progression in stage III-V chronic kidney disease patients without dialysis].

Objective: To investigate the effect of serum potassium level and hyperkalemia on the renal function decline in chronic kidney disease (CKD) patients. Methods: The clinical data at baseline and follow-up in stage Ⅲ-Ⅴ CKD patients without dialysis who were followed up for more than one year in Tianjin First Central Hospital from May 2015 to June 2019 and Teikyo University School of Medicine from January 2008 to July 2013 were retrospectively collected. All patients were divided into stable group (337 cases), slow progression group (337 cases) and rapid progression group (338 cases) according to the tertile of estimated glomerular filtration rate (eGFR) slope (the annual average percentage of eGFR decline). Multivariate logistic regression analysis models were used to evaluate the correlations of baseline serum potassium or time-averaged serum potassium level with CKD rapid progression. Results: Three hundred and forty-three cases from Tianjin First Central Hospital and 669 cases from Teikyo University School of Medicine were included in the study, and 635 cases (62.7%) were male. The average age was (61±14) years old and the average eGFR decline slope was 4.0%/year. The levels of baseline serum potassium and time-averaged serum potassium of patients in the slow progression group [(4.47±0.52) and (4.51±0.43) mmo/L] and rapid progression group [(4.62±0.62) and (4.76±0.48) mmo/L] were higher than those in the stable group [(4.37±0.49) and (4.38±0.37) mmo/L] (both P<0.05). Meanwhile, 24.6% (83/338) of the patients in the rapid progression group had hyperkalemia at baseline (serum potassium ≥5.0 mmol/L) and 34.9% (118/338) of the patients had time-averaged serum potassium ≥5.0 mmol/L, which were higher than those in the stable group [10.7% (36/337) and 6.5% (22/337)] (both P<0.001). Multivariate logistic regression analysis showed that compared with the stable group, baseline serum potassium (OR=1.843, 95%CI: 1.051-3.234) and time-averaged serum potassium (OR=2.495, 95%CI: 1.040-5.987) were correlated with the rapid progression of CKD. Time-averaged serum potassium ≥5.0 mmol/L was the independent influencing factor for rapid progression of CKD. Conclusions: During the follow-up period, the average level of serum potassium in stage Ⅲ-Ⅴ CKD patients should be controlled under 5.0 mmol/L, which may reduce the risk of rapid decline of renal function.