title: A Randomized Crossover Trial of Dietary Sodium Restriction in Stage 3-4 CKD.
abstract: OBJECTIVE
  Patients with chronic kidney disease (CKD) are often volume expanded and hypertensive. Few controlled studies have assessed the effects of a sodium-restricted diet (SRD) in CKD.
  
  
  METHODS
  We conducted a randomized crossover trial to evaluate the effect of SRD (target <2 g sodium per day) versus usual diet on hydration status (by bioelectrical impedance spectroscopy) and blood pressure (BP) between May of 2009 and May of 2013. A total of 58 adults with stage 3-4 CKD were enrolled from two academic sites: University of Michigan (n=37) and University of North Carolina at Chapel Hill (n=21); 60% were men, 43% were diabetic, 93% were hypertensive, and mean age was 61 years. Participants followed SRD or usual diet for 4 weeks, followed by a 2-week washout period and a 4-week crossover phase. During the SRD, dieticians provided counseling every 2 weeks, using motivational interviewing techniques.
  
  
  RESULTS
  Whole-body extracellular volume and calf intracellular volume decreased by 1.02 L (95% confidence interval [95% CI], -1.48 to -0.56;P<0.001) and -0.06 L (95% CI, -0.12 to -0.01;P=0.02), respectively, implying decreased fluid content on the SRD compared with usual diet. Significant reductions in urinary sodium (-57.3 mEq/24 h; 95% CI, -81.8 to -32.9), weight (-2.3 kg; 95% CI, -3.2 to -1.5), and 24-hour systolic BP (-10.8 mmHg; 95% CI, -17.0 to -4.6) were also observed (allP<0.01). Albumin-to-creatinine ratio did not change significantly and mean serum creatinine increased slightly (0.1 mg/dl; 95% CI, -0.01 to 0.2;P=0.06). No period or carryover effects were observed. Results were similar when analyzed from phase 1 only before crossover, althoughPvalues were modestly larger because of the loss of power.
  
  
  CONCLUSIONS
  In this randomized crossover trial, implementation of SRD in patients with CKD stage 3-4 resulted in clinically and statistically significant improvement in BP and hydration status. This simple dietary intervention merits a larger trial in CKD to evaluate effects on major clinical outcomes.
authors.affiliation: Division of Nephrology, Department of Internal Medicine.
authors.forename: Rajiv
authors.initials: R
authors.lastname: Saran
authors.affiliation: Department of Biostatistics, Kidney Epidemiology and Cost Center.
authors.forename: Robin L
authors.initials: RL
authors.lastname: Padilla
authors.affiliation: Department of Biostatistics, Consulting for Statistics, Computing and Analytics Research, and.
authors.forename: Brenda W
authors.initials: BW
authors.lastname: Gillespie
authors.affiliation: Division of Nephrology, Department of Internal Medicine.
authors.forename: Michael
authors.initials: M
authors.lastname: Heung
authors.affiliation: Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan.|Division Cardiology, Department of Internal Medicine, Ann Arbor Veterans Affairs Health System, Ann Arbor, Michigan.
authors.forename: Scott L
authors.initials: SL
authors.lastname: Hummel
authors.affiliation: Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Vimal Kumar
authors.initials: VK
authors.lastname: Derebail
authors.affiliation: Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan.
authors.forename: Bertram
authors.initials: B
authors.lastname: Pitt
authors.affiliation: Renal Research Institute, Research Division, New York, New York; and.
authors.forename: Nathan W
authors.initials: NW
authors.lastname: Levin
authors.affiliation: Renal Research Institute, Research Division, New York, New York; and.
authors.forename: Fansan
authors.initials: F
authors.lastname: Zhu
authors.affiliation: Renal Research Institute, Research Division, New York, New York; and.
authors.forename: Samer R
authors.initials: SR
authors.lastname: Abbas
authors.affiliation: Renal Research Institute, Research Division, New York, New York; and.
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.affiliation: Renal Research Institute, Research Division, New York, New York; and.|Division of Nephrology, Department of Internal Medicine, Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: Peter
authors.initials: P
authors.lastname: Kotanko
authors.affiliation: Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Philip
authors.initials: P
authors.lastname: Klemmer
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure; D003404:Creatinine / Q000097:blood; D018592:Cross-Over Studies; D004039:Diet, Sodium-Restricted / Q000009:adverse effects; D017097:Electric Impedance; D045604:Extracellular Fluid; D005260:Female; D006801:Humans; D007424:Intracellular Fluid; D008297:Male; D008875:Middle Aged; D062405:Motivational Interviewing; D000074267:Organism Hydration Status; D051436:Renal Insufficiency, Chronic / Q000178:diet therapy* / Q000503:physiopathology; D012709:Serum Albumin / Q000378:metabolism; D012964:Sodium / Q000652:urine; D015431:Weight Loss
chemical_list: D012709:Serum Albumin; D012964:Sodium; D003404:Creatinine
keywords: ambulatory blood pressure monitoring; bioelectrical impedance; crossover design; motivational interviewing; salt sensitivity