High dietary intake of sodium and potassium might increase the likelihood of chronic kidney disease (CKD) progression, according to a new study.
Previous trials yielded conflicting results, so a team led by Jiang He, MD, of Tulane University in New Orleans, prospectively investigated levels of these minerals and outcomes in 3,939 stage 2–4 CKD patients in the Chronic Renal Insufficiency Cohort (CRIC) study. Urinary sodium and potassium excretion were measured annually for 3 years using 24-hour urine samples to gauge habitual dietary intake. CKD progression was defined as development of end-stage renal disease or a halving of estimated glomerular filtration rate (eGFR) rate.
During follow-up, 939 instances of progression and 540 deaths occurred, according to results published online ahead of print in the Journal of the American Society of Nephrology. Compared with patients with the lowest quartile of urinary sodium (less than 116.8 mmol within 24 hours), CKD patients with the highest sodium levels (194.6 mmol or more within 24 hours) had 54% increased odds of CKD progression, 45% increased odds of early death from any cause, and a 43% increased odds of a composite of these outcomes.
Similarly, compared with patients with the lowest quartile of urinary potassium (less than 39.4 mmol within 24 hours), CKD patients with the highest urinary potassium (67.1 mmol or more within 24 hours) had 59% increased odds of CKD progression and 42% increased odds of the composite outcome (42%).
The researchers adjusted results for multiple factors, such as eGFR at baseline, urinary creatinine, and use of antihypertensive medications. Sodium-related increases in blood pressure might not explain the increased risks, they suggested, opening the possibility of other causal pathways. Proteinuria might be an important mechanism for progression, according to the investigators.
High potassium might lead to harmful effects in CKD patients, the researchers suggested, but potassium homeostasis differs by race.
“These data warrant future clinical trials to test the effect of a moderate reduction in dietary sodium and potassium intake on CKD progression in patients with high dietary sodium or potassium intake,” Dr. He stated in a news release. “The findings could ultimately impact dietary recommendations for patients with CKD to slow disease progression.”
- He J, Mills KT, Appel LJ, et al. Urinary Sodium and Potassium Excretion and CKD Progression. J Am Soc Nephrol. 27, 2015. doi: 10.1681/ASN.2015010022.
- High Dietary Sodium and Potassium May Worsen Chronic Kidney Disease [News Release]. American Society of Nephrology Public Relations; September 17, 2015. Accessed November 12, 2015.
- Most Americans Should Consume Less Sodium. Centers for Disease Control and Prevention. http://www.cdc.gov/salt/ Accessed November 12, 2015.