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


BACKGROUND
Universal Trial Number U1111-1125-2149 registered on 13/10/2011; Australian New Zealand Clinical Trials Registry Number ACTRN12611001097932 registered on 21/10/2011.
Princess Alexandra Hospital, 199 Ipswich Road, Woolloongabba, QLD, Australia. Katrina.Campbell@health.qld.gov.au.
Katrina L
KL
Campbell
David W
DW
Johnson
Judith D
JD
Bauer
Carmel M
CM
Hawley
Nicole M
NM
Isbel
Michael
M
Stowasser
Jonathan P
JP
Whitehead
Goce
G
Dimeski
Emma
E
McMahon
D054392:Adipokines / Q000097:blood*; D000368:Aged; D001826:Body Fluids / Q000378:metabolism*; D003404:Creatinine / Q000097:blood*; D004039:Diet, Sodium-Restricted / Q000379:methods*; D004311:Double-Blind Method; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D020097:Natriuretic Peptide, Brain / Q000097:blood; D010446:Peptide Fragments / Q000097:blood; D051436:Renal Insufficiency, Chronic / Q000175:diagnosis / Q000178:diet therapy* / Q000503:physiopathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
D054392:Adipokines; D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain; D003404:Creatinine