GFR decline and urinary excretion rates of sodium negatively related in CKD patients: study

Chronic kidney disease (CKD) means your kidneys are damaged and can't filter blood the way they should. The main risk factors for developing kidney disease are diabetes, high blood pressure, heart disease, and a family history of kidney failure.

Multiple 24-hour urine collections are necessary to adequately assess sodium and potassium intake. So, a group of researchers assessed kidney function decline for four years after baseline in relation to seven-time averaged 24-hour urinary sodium and potassium excretion (UNaV, UKV), their UNaV/UKV ratio, and their categorical combination in outpatients with chronic kidney disease (CKD).

This retrospective cohort study was based on 240 outpatients with baseline chronic kidney disease (CKD) stages 3-5, baseline age 20 years or more (median age 72.0 years), and a median follow-up (with interquartile range) of 2.9 (1.4– 4.0) years. Outcome was the percentage change in annual slope of estimated glomerular filtration rate (delta eGFR per year).

The results of the study are as follows:

In linear mixed models, percentage changes in delta eGFR per year were -3.26% (95% confidence interval -5.85 to -0.60), +5.20% (2.34 to 8.14), and -5.20% (-7.64 to -2.69), respectively, per one standard deviation increase in the seven-time, averaged UNaV and UKV, and their UNaV/UKV ratio. Additionally, percentage changes per year in delta eGFR per year were -16.27% (-23.57 to -8.27) in the middle-to-high UNaV and low UKV group, compared with the low UNaV and middle-to-high UKV group.

Thus, the researchers concluded that their study reinforces the observation of opposite associations between GFR decline and urinary excretion rates of sodium (positive) and potassium (negative), respectively. Whether changes in dietary sodium and potassium intake slow GFR decline still requires further study.

Reference:

A multiple 24-hour urine collection study indicates that kidney function decline is related to urinary sodium and potassium excretion in patients with chronic kidney disease by Soshiro Ogata et al. published in Kidney International.

DOI: https://doi.org/10.1016/j.kint.2021.10.030