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

Completed · Not applicable

Conditions studied: Kidney Disease

In brief

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.

Key facts

Study ID

NCT00974636

Run by

University of Michigan

People needed

35

Starts

2009-05-01

Expected to finish

2013-05-01

Last updated by the study team

2015-08-05

Who can join

Age: 18 and older, up to 85. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

• 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).

You may not qualify if…

• 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.

Where it is running

• University of North Carolina — Chapel Hill, North Carolina, United States

Full record on ClinicalTrials.gov

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