Association between 24h Urinary Sodium and Potassium Excretion and Estimated Glomerular Filtration Rate (eGFR) Decline or Death in Patients with Diabetes Mellitus and eGFR More than 30 ml/min/1.73m2

Abstract

Background: Data regarding the association between 24h urinary sodium and potassium excretion with kidney outcomes in patients with diabetes mellitus is currently scarce.

Methods: We conducted a single-center, retrospective cohort study in which 1230 patients with diabetes who had undergone a 24h urinary sodium and potassium excretion test were analyzed. Patients with incomplete urine collection were excluded based on 24h urinary creatinine excretion. Outcomes were the composite of a 30% decline in eGFR or death. Multivariate cox regression analysis was used to investigate the association between urinary sodium and potassium excretion and outcomes.

Results: With a mean follow up period of 5.47 years, 130 patients reached the outcomes (30% decline in eGFR: 124, death: 6). Mean (SD) eGFR and 24h urinary sodium and potassium excretion at baseline were 78.6 (19.5) ml/min/1.73m2, 4.50 (1.64) g/day, and 2.14 (0.77) g/day. Compared with sodium excretion < 3.0 g/day, no significant change in risk of outcomes was observed with increased increments of 1.0 g/day. Compared with potassium excretion of < 1.5 g/day, 2.0-2.5 g/day, and 2.5-3.0 g/day were significantly associated with a lower risk of outcomes (hazard ratio [HR], 0.49 and 0.44; 95% confidence interval [CI], 0.28 to 0.84 and 0.22 to 0.87).

Conclusions: 24h urinary sodium excretion was not significantly associated with a risk of 30% decline in eGFR or death in patients with diabetes. However, an increased risk of 30% decline in eGFR or death was significantly associated with 24h urinary potassium excretion < 1.5 g/day than with 2.0-2.5 g/day and 2.5-3.0 g/day.

Conflict of interest statement

Competing Interests: The authors declare the following competing interests: Kyowa Hakko Kirin Co., Ltd., Otsuka Pharmaceutical Co., Ltd., Dainippon Sumitomo Pharma Co., Ltd., and Mochida Pharmaceutical Co., Ltd. provided support in the form of research grants for other research, but did not have any additional role in the design, data collection and analysis, decision to publish, or preparation of the manuscript of this study. This does not alter the authors’ adherence to PLOS ONE policies on sharing data and materials.

Figures

Fig 1. Flowchart of number of eligible patients after screening.

Fig 2. Association between 24h (A) urinary sodium and (B) potassium excretion and hazard ratio for 30% decline in eGFR or death.

Multivariable spline regression analyses of hazard ratios and 95% confidence intervals of 30% decline of eGFR or death, adjusted for age, sex, body mass index, history of CVD, diabetic retinopathy, blood pressure, HbA1c, eGFR, uric acid, total cholesterol, high density lipoprotein, 24h urinary albumin excretion and (A) 24h urinary potassium excretion or (B) 24 urinary sodium excretion.