Human Sodium Balance Study

Study Overview
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Brief Summary
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The overall objective of this study is to examine how dietary sodium is used by the body. In a racially diverse sample of adults, the investigators will examine the effects of high and low dietary sodium intake on the storage and excretion of sodium and determine whether sodium distribution affects blood pressure. This has implications for how investigators interpret studies that use urine biomarkers of sodium. Study findings about tissue sodium storage also have implications for managing hypertension and related conditions.

Official Title
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Sodium Regulation in Individuals on Known Dietary Sodium Intake

Conditions
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Hypertension

Intervention / Treatment
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* Other: High dietary sodium intake
* Other: Low dietary sodium intake


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 18-69 years old; Diagnosed with high blood pressure; Taking no more than one medication for high blood pressure; Currently has a primary care provider; Willing to eat all meals provided by the study for a total of 50 days. Exclusion Criteria: Diabetes; Smoker; Serious food allergies; Currently pregnant or planning to become pregnant

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 69 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Dietary intervention consisting of two 25-day feeding periods separated by a 10-day washout.
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: High-low dietary sodium<br>High sodium diet (3400 mg/day) feeding period followed by low sodium diet (2300 mg/day) feeding period | Other: High dietary sodium intake<br>* Twenty five day feeding period of high dietary sodium (3400 mg/day)<br>Other: Low dietary sodium intake<br>* Twenty five day feeding period of low dietary sodium (2300 mg/day)<br>|
| Experimental: Low-high dietary sodium<br>Low sodium diet (2300 mg/day) feeding period followed by high sodium diet (3400 mg/day) feeding period | Other: High dietary sodium intake<br>* Twenty five day feeding period of high dietary sodium (3400 mg/day)<br>Other: Low dietary sodium intake<br>* Twenty five day feeding period of low dietary sodium (2300 mg/day)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Estimated sodium concentration in skin and muscle | The concentration of sodium in skin and muscle will be measured, and the difference in concentrations resulting from high versus low sodium intakes will be calculated. Skin and muscle sodium stores will be non-invasively quantified using 23sodium-magnetic resonance imaging (23Na-MRI). | 60 days | 
| Estimated sodium concentration in bone | The concentration of sodium in bone will be measured, and the difference in concentrations resulting from high versus low sodium intakes will be calculated. Sodium storage in bone will be measured non-invasively using in vivo neutron activation analysis (IVNAA) technology to quantify the concentration of Na in the hand. | 60 days | 
| Concentration of sodium, potassium, and hormone regulators in excreted urine | Urinary concentration of sodium, potassium, and hormones (renin, angiotensin, aldosterone, free cortisol, free cortisone, glucocorticoid, and mineralocorticoid) will be measured and variation over time will be calculated. | 60 days | 
| Blood pressure | Blood pressure under high versus low dietary sodium conditions will be measured. | 60 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Racial differences in concentrations of sodium in skin, muscle and bone | Blacks/African Americans mean sodium concentrations versus the average of the means of each of the other racial/ethnic groups will be examined. | 60 days | 
| Racial differences in concentration of urinary potassium excretion | The concentration of potassium excreted in urine will be compared between Blacks/African Americans versus the pooled sample of other racial/ethnic groups. | 60 days | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Blood pressure, Sodium, Salt, Randomized controlled trial, balance, humans