Clinical Trial: Dietary Salt in Postural Tachycardia Syndrome

Study Status: Active, not recruiting
Recruit Status: Active, not recruiting
Study Type: Interventional

Official Title: Dietary Salt in Postural Tachycardia Syndrome

Brief Summary: Patients with 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 DA, 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.

Detailed Summary:

Study Day 1

  • Start 150 mEq Na+/day diet (POTS patients as inpatients; healthy control subjects with CRC provided outpatient diet)
  • Start a 24h urine collection (for Na+, K+, Cr, fractionated catecholamines)
  • Blood work
  • Blood volume - carbon monoxide rebreathing

Study Day 2

  • Complete 24h urine
  • Start STUDY DIET (10 mEq Na+/day or 300 mEq Na+/day in a random order) after 3 meals of 150 mEq Na+/day are complete; water ad lib

Study Day 3 - 5

  • Continue STUDY DIET; water ad lib
  • On Day 5, a 24 hr holter combined ECG monitor will be placed on the subjects.

Study Day 6

  • Continue STUDY DIET; water ad lib
  • Remove 24h Holter combined ECG monitor and BP monitor from subject
  • Start a 24h urine collection (for Na+, K+, Cr, fractionated catecholamines)
  • Complete questionnaires
  • NPO after midnight for study next day

Study Day 7 (BIG DAY)

  • Awaken early (~6am) to void (still collecting 24h urine)
  • Patient returns to bed, IV catheter inserted
  • Posture
    Sponsor: Vanderbilt University

    Current Primary Outcome: blood volume [ Time Frame: after 7 days of each dietary sodium level ]

    DAXOR (131-I labelled albumin) blood volume assay


    Original Primary Outcome: Same as current

    Current Secondary Outcome: Magnitude of suppression of aldosterone (from low sodium to high sodium diets) and a reduction in orthostatic tachycardia and orthostatic symptoms in POTS patients with the high-sodium diet. [ Time Frame: after 7 days of each dietary sodium intervention ]

    Whether plasma renin activity and aldosterone are modified appropriately by changes in dietary sodium in POTS & whether patients with POTS have improvements in their orthostatic tachycardia and symptoms as a result of a high dietary sodium level.


    Original Secondary Outcome: Same as current

    Information By: Vanderbilt University Medical Center

    Dates:
    Date Received: March 2, 2012
    Date Started: March 2012
    Date Completion: March 2018
    Last Updated: April 3, 2017
    Last Verified: April 2017