Urinary Sodium and Potassium Excretion and CKD Progression

Abstract

CKD is a major risk factor for ESRD, cardiovascular disease, and premature death. Whether dietary sodium and potassium intake affect CKD progression remains unclear. We prospectively studied the association of urinary sodium and potassium excretion with CKD progression and all-cause mortality among 3939 patients with CKD in the Chronic Renal Insufficiency Cohort Study. Urinary sodium and potassium excretion were measured using three 24-hour urine specimens, and CKD progression was defined as incident ESRD or halving of eGFR. During follow-up, 939 CKD progression events and 540 deaths occurred. Compared with the lowest quartile of urinary sodium excretion (<116.8 mmol/24 h), hazard ratios (95% confidence intervals) for the highest quartile of urinary sodium excretion (≥194.6 mmol/24 h) were 1.54 (1.23 to 1.92) for CKD progression, 1.45 (1.08 to 1.95) for all-cause mortality, and 1.43 (1.18 to 1.73) for the composite outcome of CKD progression and all-cause mortality after adjusting for multiple covariates, including baseline eGFR. Additionally, compared with the lowest quartile of urinary potassium excretion (<39.4 mmol/24 h), hazard ratios for the highest quartile of urinary potassium excretion (≥67.1 mmol/24 h) were 1.59 (1.25 to 2.03) for CKD progression, 0.98 (0.71 to 1.35) for all-cause mortality, and 1.42 (1.15 to 1.74) for the composite outcome. These data indicate that high urinary sodium and potassium excretion are associated with increased risk of CKD progression. Clinical trials are warranted to test the effect of sodium and potassium reduction on CKD progression.

Keywords: CKD; ESRD; epidemiology and outcomes; nutrition.

Copyright © 2016 by the American Society of Nephrology.

Figures

Figure 1.

Association of urinary sodium and potassium excretion with cumulative hazard rates of CKD and all-cause mortality. Kaplan-Meier plots of multiple-adjusted cumulative hazard rates of CKD progression, all-cause mortality, and a composite outcome of CKD progression or all-cause mortality according to the quartile of urinary sodium and potassium excretion among 3757 patients with CKD (the CRIC Study). Panel A: urinary sodium excretion and CKD progression; Panel B: urinary sodium excretion and all-cause mortality; Panel C: urinary sodium excretion and a composite outcome of CKD progression or all-cause mortality; Panel D: urinary potassium excretion and CKD progression; Panel E: urinary potassium excretion and all-cause mortality; Panel F: urinary potassium excretion and a composite outcome of CKD progression or all-cause mortality.

Figure 2.

Association of urinary sodium and potassium excretion with hazard ratios of CKD and all-cause mortality. Multivariable spline regression analyses of hazard ratios and 95% confidence intervals of CKD progression, all-cause mortality, and a composite outcome of CKD progression or all-cause mortality associated with 24-hour urinary sodium and potassium excretion among 3757 patients with CKD (the CRIC Study). Panel A: urinary sodium excretion and CKD progression; Panel B: urinary sodium excretion and all-cause mortality; Panel C: urinary sodium excretion and a composite outcome of CKD progression or all-cause mortality; Panel D: urinary potassium excretion and CKD progression; Panel E: urinary potassium excretion and all-cause mortality; Panel F: urinary potassium excretion and a composite outcome of CKD progression or all-cause mortality.