Dietary Sodium's Effect on Urinary Sodium and Dopamine Excretion in Patients With Postural Tachycardia Syndrome

NCT01563107 | Completed Results

• 2 other identifiers: VUMC 111633R01HL071784
• Study Type: interventional
• Target: 38
• Locations: 1 country
• Sites: 1

Brief Summary

Patients with Postural Tachycardia Syndrome (POTS) may not adequately expand their plasma volume in response to a high sodium diet. Mechanisms involved in the regulation of plasma volume, such as the renin-angiotensin-aldosterone system and renal dopamine (DA), may be impaired in POTS and may respond inappropriately to changes in dietary sodium. The investigators propose that the changes in urinary sodium and dopamine excretion caused by consuming low-sodium and high-sodium diets will be different between patients with POTS and healthy volunteers. The purpose of this study is to determine (1) whether changes in dietary sodium level appropriately influence sodium excretion in POTS; (2) whether changes in dietary sodium level appropriately influence DA excretion in POTS; (3) whether a high dietary sodium level appropriately expands plasma volume in POTS; and (4) whether patients with POTS have improvements in their orthostatic tachycardia and symptoms as a result of a high dietary sodium level.

Conditions

Postural Orthostatic Tachycardia Syndrome

Keywords

Orthostatic Intolerance; Tachycardia; Orthostatic Hypotension; Sodium

Outcome Measures

Primary Outcomes (2)

• 24hr Urinary Sodium

  Amount of sodium excreted in urine over 24hr ending on Day 7

  Day 6 am - Day 7 am for each dietary sodium level

• 24hr Urinary Dopamine

  Amount of dopamine excreted in urine over 24 hours ending on Day 7

  Between Day 6 am - Day 7 am of each dietary sodium level

Secondary Outcomes (13)

• Plasma Volume

  after 7 days of each dietary sodium level

• Magnitude of Orthostatic Tachycardia

  Supine and upright heart rate were measured after 6 days of each dietary sodium level

• Upright Symptom Score

  Upright symptoms were assessed on the 6th day of low or high sodium diet.

• Urinary Sodium Following Change in Dietary Sodium Days 1-2

  24 hour collections ending on Day 2 of each diet phase

• Urinary Dopamine Following Change in Dietary Sodium Days1-2

  24 hour collections ending on Day 2 of each dietary sodium phase

Study Arms (2)

High Salt Diet

EXPERIMENTAL

POTS and healthy controls will be randomly assigned the order of dietary sodium levels. All procedures are performed at both levels. The high sodium diet will provide 300 milliequivalents (mEq) sodium/day.

Radiation: Plasma Volume; Procedure: Exercise Capacity Test - Bicycle; Procedure: Posture Study

Low Salt Diet

EXPERIMENTAL

POTS and healthy controls will be randomly assigned the order of dietary sodium levels. All procedures are performed at both levels. The low sodium diet will provide 10 mEq sodium/day.

Radiation: Plasma Volume; Procedure: Exercise Capacity Test - Bicycle; Procedure: Posture Study

Interventions

Plasma Volume RADIATION

Using injection of iodinated I-131 tagged human serum albumin nominally 25 micro-Ci of radiation, blood samples are drawn before and 30 minutes after injection.

Also known as: DAXOR

High Salt Diet; Low Salt Diet

Exercise Capacity Test - Bicycle PROCEDURE

subjects breathe room air through a mouthpiece and exhale the air into a tube that connects to a machine (metabolic cart) that analyzes carbon dioxide and oxygen content, which allows the investigator to calculate the amount of oxygen they are using under resting and exercise conditions.

Also known as: VO2 Max (maximal oxygen consumption)

High Salt Diet; Low Salt Diet

Posture Study PROCEDURE

Blood pressure and heart rate will be measured while supine and then while standing for up to 30 minutes. Blood will be drawn in each position to measure hormones that regulate blood pressure and blood volume.

Also known as: Standing Orthostatic Challenge

High Salt Diet; Low Salt Diet

Eligibility Criteria

• Age: 18 Years - 50 Years
• Sex: female
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Premenopausal patients with POTS and healthy volunteers, 18-50 years old, who are non-smokers and free of medications with the potential to influence blood pressure
• Patients diagnosed with postural tachycardia syndrome by the Vanderbilt Autonomic Dysfunction Center
• Patients who Increase heart rate ≥30 beats/min with position change from supine to standing (10 minutes)
• For patients, chronic symptoms consistent with POTS that are worse when upright and get better with recumbence
• Only female participants are eligible. Since 80-90% of POTS patients are female, and there can be differences in measures with the menstrual cycle, including a small number of males might introduce a significant amount of noise.
• Able and willing to provide informed consent

You may not qualify if:

• Smokers
• Overt cause for postural tachycardia, i.e., acute dehydration
• Significant cardiovascular, pulmonary, hepatic, or hematological disease by history or screening results
• Positive pregnancy test or breastfeeding
• Hypertension defined as BP\>145/95 off medications when supine or needing antihypertensive medication
• Other factors which in the investigator's opinion would prevent the participant from completing the protocol, including poor compliance during previous studies or an unpredictable schedule
• Unable to give informed consent

Sponsors & Collaborators

• Vanderbilt University Medical Center: lead
• National Heart, Lung, and Blood Institute (NHLBI): collaborator

Study Sites (1)

Vanderbilt University Medical Center

Nashville, Tennessee, 37232, United States

Location

MeSH Terms

Conditions

Postural Orthostatic Tachycardia Syndrome; Orthostatic Intolerance; Tachycardia; Hypotension, Orthostatic

Interventions

Plasma Volume

Condition Hierarchy (Ancestors)

Primary Dysautonomias; Autonomic Nervous System Diseases; Nervous System Diseases; Neurologic Manifestations; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Arrhythmias, Cardiac; Heart Diseases; Cardiovascular Diseases; Cardiac Conduction System Disease; Pathologic Processes; Hypotension; Vascular Diseases

Intervention Hierarchy (Ancestors)

Blood Volume; Blood Physiological Phenomena; Circulatory and Respiratory Physiological Phenomena; Hemodynamics; Cardiovascular Physiological Phenomena

Results Point of Contact

• Title: Alfredo Gamboa MD
• Organization: Vanderbilt University Medical Center

alfredo.gamboa@vumc.org

6158751003

Study Officials

• Alfredo Gamboa, MD

  Vanderbilt University Medical Center

  PRINCIPAL INVESTIGATOR

Publication Agreements

• PI is Sponsor Employee: Yes

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Associate Professor

Model Details: Randomization tables will be used to determine whether the 10 milliequivalents (mEq) sodium/day or 300 mEq sodium/day diet will be consumed first. Both diets will be completed on each subject (randomized crossover study), so all of the study procedures (after screening) will be repeated.

Study Record Dates

• First Submitted: March 22, 2012
• First Posted: March 26, 2012
• Study Start: March 1, 2012
• Primary Completion: December 1, 2020
• Study Completion: December 1, 2020
• Last Updated: January 25, 2022
• Results First Posted: January 25, 2022

Record last verified: 2021-12

Locations

US (1)