Lowering Salt Intake in Chronic Kidney Disease: A Pilot Randomized Crossover Trial
Condition: Kidney Disease
MeSH terms: Kidney Diseases; Renal Insufficiency, Chronic
Study type: Interventional

Summary: 
      ABSTRACT

      Background:

      It is well recognized that excess dietary salt intake plays a major role in the development
      of hypertension. Chronic Kidney Disease (CKD) is associated with excess salt and water
      retention (excess volume) which is associated with hypertension.

      Hypotheses:

      Hypothesis 1:

      Dietary salt restriction will improve volume status in subjects with CKD stages 3-4 as
      assessed by Bioelectrical Impedance Analysis (BIA).

      Hypothesis 2:

      Dietary salt restriction will result in improved blood pressure control in patients with CKD
      stages 3-4.

      Hypothesis 3:

      Dietary salt restriction will decrease albuminuria in patients with CKD stages 3-4.

      Patients and Trial Design: This randomized crossover pilot study is designed to assess the
      effect of salt restriction on volume status in patients with CKD stages 3 and 4.

      Subjects will be randomized to a treatment order: (1) 4 weeks of salt restriction of <85 mmol
      sodium per day, a 2 week washout period, and 4 weeks of usual salt diet, OR (2) 4 weeks of
      usual diet, 2 weeks washout, and 4 weeks of salt restriction. Patients will receive dietary
      counseling in person at each study visit and at weekly intervals by phone calls from study
      dieticians. At weeks 0, 4, 6 and 10, patients will undergo assessments for (i) physical
      examination with assessments for weight, blood pressure, pulse, anthropometrics and a
      standardized clinical assessment of volume status. (ii) volume status using bioelectrical
      impedance analysis (BIA) (iii) 24-hour urine testing for, albumin, creatinine and aldosterone
      Every 2 weeks throughout the study, a 24-hour urine sodium will be measured for compliance,
      and serum electrolytes will be assessed for safety.

      Data Analysis: BIA measurements in the low salt group will be compared with the regular diet
      group using the standard linear model analysis for 2x2 crossover trials. Additionally,
      24-hour ambulatory and static blood pressure and 24-hour urine aldosterone levels will be
      compared between the two groups.

      Future Implications: A significant reduction in the degree of volume expansion (as assessed
      by BIA) and blood pressure as a result of a salt restricted diet would have implications for
      renal and cardiovascular protection and would warrant confirmation by a larger randomized
      trial.
    


Intervention name(s): Low Salt Diet; Usual Salt Diet
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): Dietary sodium restriction of ≤2.0 g/day or ≤ 85 mmol/day; Usual salt intake (approximately >180-200 mmol/day in the average American diet).
Other intervention name(s): Low salt diet, CKD, Bioimpedance analysis (BIA)
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: None (Open Label)
Keywords: Kidney Disease; Albuminuria; Glomerular filtration rate; Volume status; Bioimpedance analysis