Dietary Salt in Postural Tachycardia Syndrome

Summary

Patients with POTS may not adequately expand their plasma volume in response to a high-sodium (Na+) diet. Mechanisms involved in the regulation of plasma volume, such as the renin-angiotensin-aldosterone system and renal dopamine, may be impaired in POTS and may respond inappropriately to changes in dietary sodium.The purpose of this study is to determine (1) whether a high dietary sodium level appropriately expands plasma volume in POTS; (2) whether plasma renin activity and aldosterone are modified appropriately by changes in dietary sodium in POTS; and (3) 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

Interventions

RADIATION

Blood Volume

we will measure the amount of hemoglobin and myoglobin in the body by a procedure called CO rebreathing. One teaspoon of blood is taken before and after a small amount of CO has been absorbed into the bloodstream.

RADIATION

Total Blood Volume

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

PROCEDURE

Exercise Capacity Test - Bicycle

subjects breath 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.

PROCEDURE

Posture Study

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.

Sponsors & Collaborators

• National Institutes of Health (NIH)

  collaborator NIH

• National Heart, Lung, and Blood Institute (NHLBI)

  collaborator NIH

• Vanderbilt University

  lead OTHER

Principal Investigators

• Alfredo J Gamboa, MD · Vanderbilt University

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

NONE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

50 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2012-03-31

Primary Completion

2020-12-31

Completion

2021-12-31

Countries

• United States

Study Locations