Lowering Salt Intake in Chronic Kidney Disease: A Pilot Randomized Crossover Trial

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.

Conditions

• Kidney Disease

Interventions

DIETARY_SUPPLEMENT

Low Salt Diet

Dietary sodium restriction of ≤2.0 g/day or ≤ 85 mmol/day

DIETARY_SUPPLEMENT

Usual Salt Diet

Usual salt intake (approximately \>180-200 mmol/day in the average American diet).

Sponsors & Collaborators

• Renal Research Institute

  collaborator OTHER

• University of Michigan

  lead OTHER

Principal Investigators

• Rajiv Saran, MD · University of Michigan

Study Design

Allocation

RANDOMIZED

Masking

NONE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

85 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2009-05-31

Primary Completion

2013-02-28

Completion

2013-05-31

Countries

• United States

Study Locations