Serum sodium levels increase significantly with decreasing renal function, according to the findings of a small study presented at the 52nd congress of the European Renal Association-European Dialysis and Transplant Association in London.

The retrospective observational study, led by Pauline A. Swift, MBChB, of the South West Thames Renal Unit, St. Helier Hospital, London, studied 42 patients with chronic kidney disease (mean estimated glomerular filtration rate [eGFR] of 38.2 mL/min/1.73 m2 at time zero) and who had a mean follow-up period of 63.4 months. The researchers found that each 1 mL/min/1.73 m2 decrease in eGFR was associated with a significant 0.020 mmol/L increase in serum sodium. On average, eGFR declined by 5.0 mL/min/1.73 m2 per year.

“This study has shown a small but significant increase in serum sodium with decreasing eGFR,” the authors concluded in a poster presentation. “This is a novel finding and one that supports the suggestion that salt balance is likely to be an important factor in the development of high blood pressure in this population.”

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The researchers noted that hypertension increases in prevalence as CKD progresses, and it is likely that salt intake plays an increasingly important role in blood pressure regulation with declining kidney function.