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

This study has been completed.
Renal Research Institute
Information provided by (Responsible Party):
Rajiv Saran, University of Michigan Identifier:
First received: September 9, 2009
Last updated: August 4, 2015
Last verified: August 2015



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.


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.

Condition Intervention
Kidney Disease Dietary Supplement: Low Salt Diet Dietary Supplement: Usual Salt Diet

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)
Official Title: Lowering Salt Intake in Chronic Kidney Disease: A Pilot Randomized Crossover Trial

Resource links provided by NLM:

Further study details as provided by Rajiv Saran, University of Michigan:

Primary Outcome Measures:
  • Primary Outcome: Change in volume status (intracellular, extracellular volume, and total body water) as measured by BIA using both whole body and segmental techniques [ Time Frame: 12 Weeks ]

Enrollment: 35
Study Start Date: May 2009
Study Completion Date: May 2013
Primary Completion Date: February 2013 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Low Salt Diet
Dietary sodium restriction of ≤2.0 g/day or ≤ 85 mmol/day for two weeks
Dietary Supplement: Low Salt Diet
Dietary sodium restriction of ≤2.0 g/day or ≤ 85 mmol/day
Other Name: Low salt diet, CKD, Bioimpedance analysis (BIA)
Placebo Comparator: Ususal Salt Diet
Usual salt intake (approximately >180-200 mmol/day in the average American diet).
Dietary Supplement: Usual Salt Diet
Usual salt intake (approximately >180-200 mmol/day in the average American diet).


Ages Eligible for Study:   18 Years to 85 Years   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

Individuals eligible to participate in this study must meet all of the following criteria:

  • Willing and able to provide written, signed informed consent after the nature of the study has been explained, and prior to any research-related procedures.
  • Age ≥ 18 years and ≤ 85 years.
  • Willing and able to comply with all study procedures.
  • Patients with eGFR of 20 to 60 ml/min/173m2 by the abbreviated (4-variable) MDRD equation and a relatively stable clinical course.
  • Sitting systolic blood pressure ≥ 100 mmHg prior to study entry (to exclude people at risk from hypotension from dietary salt reduction).

Exclusion Criteria:

Individuals who meet any of the following exclusion criteria will not be eligible to participate in the study:

  • Recent acute illness (≤1 month). Minor ailments such as a recovered common cold or allergic rhinitis would not be considered as exclusion criteria but would be left to the site PI's discretion.
  • Recent hospitalization (≤1 month) unless clearly for a minor elective procedure unlikely to interfere with BIA measurements. The final decision will be left to the site PI's discretion.
  • Any psychological condition (including alcoholism) that could interfere with the patient's ability to comply with the study protocol.
  • Subjects with baseline 24-hour urinary sodium excretion ≤100 mmol/day.
  • Amputation of a limb other than fingers or toes.
  • Pacemaker, defibrillator, implantable pump, artificial joint, pins, plates or other types of metal objects in the body (other than dental fillings).
  • Coronary stents or metal suture material in the heart.
  • Use of any investigational product or investigational medical device within 30 days prior to screening, or requirement for any investigational agent prior to completion of all scheduled study assessments.
  • Weight over 300 pounds (limitation for examination table).
  • Pregnancy or lactation.
  • Patients with kidney diseases known to be associated with salt wasting (see above).
  • Patients with atrial fibrillation as ambulatory blood pressure measurements may not be accurate in this setting.
  • Any condition that, in the view of the PI, places the subject at high risk of poor treatment compliance or of not completing the study.
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00974636

United States, North Carolina
University of North Carolina
Chapel Hill, North Carolina, United States, 27599
Sponsors and Collaborators
University of Michigan
Renal Research Institute
Principal Investigator: Rajiv Saran, MD University of Michigan
  More Information

Responsible Party: Rajiv Saran, MD, MS, MRCP, Associate Professor, University of Michigan Identifier: NCT00974636     History of Changes
Other Study ID Numbers: HUM00016384
Study First Received: September 9, 2009
Last Updated: August 4, 2015

Keywords provided by Rajiv Saran, University of Michigan:
Kidney Disease
Glomerular filtration rate
Volume status
Bioimpedance analysis

Additional relevant MeSH terms:
Kidney Diseases
Renal Insufficiency, Chronic
Urologic Diseases
Renal Insufficiency processed this record on September 21, 2017