Open Access Highly Accessed Research article

A randomized trial of sodium-restriction on kidney function, fluid volume and adipokines in CKD patients

Katrina L Campbell123*, David W Johnson123, Judith D Bauer2, Carmel M Hawley123, Nicole M Isbel123, Michael Stowasser123, Jonathan P Whitehead234, Goce Dimeski25 and Emma McMahon12

Author Affiliations

1 Princess Alexandra Hospital, 199 Ipswich Road, Woolloongabba, QLD, Australia

2 University of Queensland, Brisbane, QLD, Australia

3 Translational Research Institute, Brisbane, QLD, Australia

4 Mater Research Institute, The University of Queensland, Brisbane, QLD, Australia

5 Chemical Pathology, Pathology Queensland, Princess Alexandra Hospital, Brisbane, QLD, Australia

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BMC Nephrology 2014, 15:57  doi:10.1186/1471-2369-15-57

Published: 4 April 2014

Abstract

Background

Dietary sodium restriction is a key management strategy in chronic kidney disease (CKD). Recent evidence has demonstrated short-term reduction in blood pressure (BP) and proteinuria with sodium restriction, however the effect on other cardiovascular-related risk factors requires investigation in CKD.

Methods

The LowSALT CKD study involved 20 hypertensive Stage III-IV CKD patients counselled by a dietitian to consume a low-sodium diet (<100 mmol/day). The study was a randomised crossover trial comparing 2 weeks of high-sodium (additional 120 mmol sodium tablets) and low-sodium intake (placebo). Measurements were taken after each crossover arm including BP (peripheral and central), adipokines (inflammation markers and adiponectin), volume markers (extracellular-to-intracellular [E/I] fluid ratio; N-terminal pro-brain natriuretic peptide [NT-proBNP]), kidney function (estimated Glomerular Filtration Rate [eGFR]) and proteinuria (urine protein-creatinine ratio [PCR] and albumin-creatinine ratio [ACR]). Outcomes were compared using paired t-test for each cross-over arm.

Results

BP-lowering benefits of a low-sodium intake (peripheral BP (mean ± SD) 148/82 ± 21/12 mmHg) from high-sodium (159/87 ± 15/10 mmHg) intake were reflected in central BP and a reduction in eGFR, PCR, ACR, NTproBNP and E/I ratio. There was no change in inflammatory markers, total or high molecular weight adiponectin.

Conclusions

Short-term benefits of sodium restriction on BP were reflected in significant change in kidney function and fluid volume parameters. Larger, long-term adequately powered trials in CKD are necessary to confirm these results.

Trial registration

Universal Trial Number U1111-1125-2149 registered on 13/10/2011; Australian New Zealand Clinical Trials Registry Number ACTRN12611001097932 registered on 21/10/2011.

Keywords:
Dietary sodium; Nutrition; Chronic kidney disease; Cardiovascular disease; Blood pressure; Kidney function; Inflammation