Postural Tachycardia SyndromeNCT01783288
Aldosterone & Sodium Regulation in Postural Tachycardia Syndrome - Screening
A study testing Autonomic Function Testing, Posture Study and Measurement of Total Blood Volume in people with Postural Tachycardia Syndrome, run by Vanderbilt University at 1 site in United States.
Trial summary
The purpose of the study is to determine whether patients meet criteria for Postural Tachycardia Syndrome (or not) and have reduced blood volume (or not). Both of these are important screening elements to Aim 3 of a National Institutes of Health Grant. The purposes of Aim 3 are to determine 1. Read more about this study
- Who is it for?
- Ages 18 to 50 years, women onlyHealthy volunteers can take part
- Conditions the study is for
- Postural Tachycardia Syndrome
- What is being tested?
- Autonomic Function Testing, Posture Study and Measurement of Total Blood Volume
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 110 participants
- Where
- 1 siteUnited States
- Study dates
- Feb 2013to Dec 2026
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 50 years
- Women only
- Healthy volunteers accepted
- Adult
Who may be able to join
- Age between 18-50 years old
- Patients with suspected POTS and healthy volunteers
- Sedentary healthy subjects of similar age and gender than patients will also be recruited.
- Only female participants are eligible.
- Able and willing to provide informed consent
Who cannot join
- Smokers
- Overt cause for postural tachycardia, i.e., acute dehydration
- Significant cardiovascular, pulmonary, hepatic, or hematological disease by history or prior testing
- Highly trained athletes
- Subjects with somatization or severe anxiety symptoms will be excluded
- Pregnant (positive pregnancy test) or breastfeeding
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- Hypertension defined as supine resting BP>145/95 mmHg off medications 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
Trial locations and contacts
1 site in 1 country.
United States1 site
Vanderbilt University Medical Center
Nashville, Tennessee, 37232
About this study
Official title: Aldosterone and Sodium Regulation in Postural Tachycardia Syndrome - Screening Protocol
The purpose of the study is to determine whether patients meet criteria for Postural Tachycardia Syndrome (or not) and have reduced blood volume (or not). Both of these are important screening elements to Aim 3 of a National Institutes of Health Grant. The purposes of Aim 3 are to determine 1. whether a high dietary sodium level appropriately expands plasma volume in Postural Orthostatic Tachycardia, 2. whether plasma renin activity and aldosterone are modified appropriately by changes in dietary sodium in Postural Tachycardia Syndrome and 3. whether patients with Postural Tachycardia Syndrome have improvements in their orthostatic tachycardia and symptoms as a result of a high dietary sodium level.
Read the detailed description
The protocol consists of a screening visit and evaluation of their autonomic nervous system status. The following activities are part of this study. Subjects may stay for 2 nights and 3 study days.
Day 0 Participants will be admitted to the Clinical Research Center, their medical history, physical exam, routine lab work (hemoglobin/hematocrit \& CMP) and a serum pregnancy test will be done during that first day. They will also be asked to fill out a health questionnaire. Later that day they will be evaluated to determine the extent of fatigue, depression and anxiety ratings, autonomic symptoms and quality of life, with the use of questionnaires.
Subjects may be asked to stop taking some medications for up to 7 days; it will be decided on an individual basis and after considering each medication and its effect to the autonomic nervous system. If subjects are asked to discontinue the medication, they will ask them to keep a diary of symptoms and to contact the PI or staff by phone if any new symptom appears. If necessary, medications will be restarted.
Testing day 1:
In the morning during the posture test, 5 teaspoons of blood will be drawn while subject is lying down, and after sitting and or standing for 30 minutes to measure substances produced by the body in response to inflammation and oxidative stress and to determine hormones that regulate the blood pressure. Blood pressure and heart rate will be measured in these different positions. A total of 10 tablespoons will be drawn.
In the afternoon, more tests will be performed designed to determine how well the autonomic nervous system is working in regulating blood pressure and heart rate. Autonomic function test will be performed to see how the involuntary nervous system is working. For these tests, heart rate will be recorded using a continuous electrocardiographic trace, blood pressure using a cuff around one arm and/or finger and heart's pumping capacity (cardiac output) will be measured by analyzing the shift of fluids in the body (body impedance) and/or by analyzing the air that is breathe.
Participants will be tilted up on a tilt table for 10 minutes while recording their heart rate and blood pressure. The autonomic function tests include asking the participants to breathe deeply for two minutes and breathing rapidly for 30 seconds, maintaining a handgrip for 3 minutes, blowing against pressure for 15 seconds and placing one hand in ice water for 1 minute. All these tests are meant to stimulate the autonomic nervous system to produce changes in blood pressure and heart rate of short duration that reflect how well the involuntary nervous system is working.
Testing day 2:
In the morning, total blood volume will be measured by using iodinated I-131 tagged human serum albumin, a material with a very small amount of radioactive substance. The test involves drawing a blood sample before the I-131 is given, then giving the I-131 through a catheter in one vein, waiting 12 minutes before the second blood sample is drawn to check its concentration. Blood samples will also be drawn while subjects are lying down to measure for hormones, which control blood pressure and heart rate. Blood will drawn at several points during the study. The total amount of blood drawn during this study is approximately 3 teaspoons.
In the afternoon, exercise capacity test with estimation of maximal oxygen consumption (VO2 max) will be done. This test will be conducted on a stationary bicycle and the resistance will be gradually increased while the expired air is measured during exhaustive physical work. The test will last approximately 30 minutes. A mouthpiece with a one way re-breathing valve attached to a breathing tube will be used to collect air samples during the exercise test. Essentially, subjects will breathe room air through a mouthpiece, and then expire the air into a tube that connects to a machine (metabolic cart). This machine analyzes carbon dioxide and oxygen content, which allows us to calculate the amount of oxygen they are using under resting and exercise conditions.
The workload will be gradually increased on the bike by increasing the resistance. As the workload increases, oxygen consumption also increases. Throughout the test period exhaled air will be collected. When subjects can no longer continue, the test will be stopped. Blood pressure will be measured at the end of each resistance-stage. Heart rate data will be recorded continuously.
Before and after completing the exercise test, subjects will be required to complete a "warm-up" and "cool-down" session including stretching exercises.
- Conditions
- Postural Tachycardia Syndrome
- Being tested
- Autonomic Function Testing, Posture Study, Measurement of Total Blood Volume, Exercise Capacity Test
- Keywords
- Postural tachycardia syndrome, orthostatic intolerance, orthostatic tachycardia, POTS
- Medical subject headings
- Postural Orthostatic Tachycardia Syndrome, Orthostatic Intolerance
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Autonomic Function TestingOther
heart rate and blood pressure will be continuously monitored while participants undergo a variety of breathing techniques (deep breathing, rapid breathing, blowing against resistance) and during sustained handgrip and cold pressor (hand in ice water). All tests are meant to stimulate the autonomic nervous system to produce changes in blood pressure and heart rate of short duration that reflect how well the autonomic nervous system is functioning.
Also during autonomic function testing, cardiac output will be measured to analyze the shift of fluids in the body (body impedance) and / or by analyzing the air that is breathed.
Posture StudyOther
Also called Supine & standing blood pressure, heart rate & blood draws.
Blood pressure, heart rate and blood samples (for catecholamines and hormones) will be measured \& collected in the supine (lying) and upright position for each participant.
Measurement of Total Blood VolumeProcedure or surgery
Also called blood sample at baseline and at 12 minutes, I-131 is administered.
Total blood volume is measured by using iodinated I-131 tagged human serum albumin.
Exercise Capacity TestOther
Also called Masimal Oxygen Consumption Test
Participants will ride on a stationary recumbent bicycle and the resistance will be gradually increased while expired air is measured.
| Study group | Role | What they receive |
|---|---|---|
| All participants | Other | All participants will be administered all procedures as described previously.
Interventions:
Autonomic Function Testing, Posture Study ,Measurement of Total Blood Volume ,Exercise Capacity Test Receives: Other: Autonomic Function Testing; Other: Posture Study; Procedure: Measurement of Total Blood Volume; Other: Exercise Capacity Test |
What is being measured
The primary outcome is the main question the study is designed to answer.
blood volume deviation (%) from individual predicted volumes
Compare blood volume deviations using the 131-I-Albumin method. Deviations will be reported as a percentage deviation from an individual's predicted value. These values will be compared between POTS patients and healthy control groups.
Measured: 2 days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted4 Feb 2013 (estimated)
- Study startFeb 2013
- Primary completionDec 2026 (estimated)
- Study completionDec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Postural Tachycardia SyndromeStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Screening
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 110 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Vanderbilt University
- Sponsor type
- University, hospital or other
- Collaborators
- National Institutes of Health (NIH), National Heart, Lung, and Blood Institute (NHLBI)
- Responsible party
- Principal investigator, Alfredo Gamboa, Vanderbilt University
- Investigators
- Alfredo J Gamboa, MD, Principal investigator, Vanderbilt University Medical Center
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT01783288
- Sponsor's protocol ID
- IRB 121817
- Other IDs
- R01HL102387
- Status last verified
- Jan 2026
- First submitted
- 25 Jan 2013
- Last updated
- 13 Jan 2026
- Results posted
- No
- Data monitoring committee
- No
Study at a glance
From the registry record, last updated by the sponsor on 13 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Aldosterone and Sodium Regulation in Postural Tachycardia Syndrome - Screening Protocol
- ClinicalTrials.gov ID
- NCT01783288
- Acronym / sponsor ID
- IRB 121817
- Conditions
- Postural Tachycardia Syndrome
- Keywords
- Postural tachycardia syndrome, orthostatic intolerance, orthostatic tachycardia, POTS
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 110 participants (estimated)
- Lead sponsor
- Vanderbilt UniversityUniversity, hospital or other
- Collaborators
- National Institutes of Health (NIH), National Heart, Lung, and Blood Institute (NHLBI)
- Study start
- Feb 2013 (actual)
- Primary completion
- Dec 2026 (estimated)
- Study completion
- Dec 2026 (estimated)
- First posted
- 4 Feb 2013 (estimated)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of the study is to determine whether patients meet criteria for Postural Tachycardia Syndrome (or not) and have reduced blood volume (or not). Both of these are important screening elements to Aim 3 of a National Institutes of Health Grant. The purposes of Aim 3 are to determine 1. whether a high dietary sodium level appropriately expands plasma volume in Postural Orthostatic Tachycardia, 2. whether plasma renin activity and aldosterone are modified appropriately by changes in dietary sodium in Postural Tachycardia Syndrome and 3. whether patients with Postural Tachycardia Syndrome have improvements in their orthostatic tachycardia and symptoms as a result of a high dietary sodium level.
Detailed description
The protocol consists of a screening visit and evaluation of their autonomic nervous system status. The following activities are part of this study. Subjects may stay for 2 nights and 3 study days.
Day 0 Participants will be admitted to the Clinical Research Center, their medical history, physical exam, routine lab work (hemoglobin/hematocrit \& CMP) and a serum pregnancy test will be done during that first day. They will also be asked to fill out a health questionnaire. Later that day they will be evaluated to determine the extent of fatigue, depression and anxiety ratings, autonomic symptoms and quality of life, with the use of questionnaires.
Subjects may be asked to stop taking some medications for up to 7 days; it will be decided on an individual basis and after considering each medication and its effect to the autonomic nervous system. If subjects are asked to discontinue the medication, they will ask them to keep a diary of symptoms and to contact the PI or staff by phone if any new symptom appears. If necessary, medications will be restarted.
Testing day 1:
In the morning during the posture test, 5 teaspoons of blood will be drawn while subject is lying down, and after sitting and or standing for 30 minutes to measure substances produced by the body in response to inflammation and oxidative stress and to determine hormones that regulate the blood pressure. Blood pressure and heart rate will be measured in these different positions. A total of 10 tablespoons will be drawn.
In the afternoon, more tests will be performed designed to determine how well the autonomic nervous system is working in regulating blood pressure and heart rate. Autonomic function test will be performed to see how the involuntary nervous system is working. For these tests, heart rate will be recorded using a continuous electrocardiographic trace, blood pressure using a cuff around one arm and/or finger and heart's pumping capacity (cardiac output) will be measured by analyzing the shift of fluids in the body (body impedance) and/or by analyzing the air that is breathe.
Participants will be tilted up on a tilt table for 10 minutes while recording their heart rate and blood pressure. The autonomic function tests include asking the participants to breathe deeply for two minutes and breathing rapidly for 30 seconds, maintaining a handgrip for 3 minutes, blowing against pressure for 15 seconds and placing one hand in ice water for 1 minute. All these tests are meant to stimulate the autonomic nervous system to produce changes in blood pressure and heart rate of short duration that reflect how well the involuntary nervous system is working.
Testing day 2:
In the morning, total blood volume will be measured by using iodinated I-131 tagged human serum albumin, a material with a very small amount of radioactive substance. The test involves drawing a blood sample before the I-131 is given, then giving the I-131 through a catheter in one vein, waiting 12 minutes before the second blood sample is drawn to check its concentration. Blood samples will also be drawn while subjects are lying down to measure for hormones, which control blood pressure and heart rate. Blood will drawn at several points during the study. The total amount of blood drawn during this study is approximately 3 teaspoons.
In the afternoon, exercise capacity test with estimation of maximal oxygen consumption (VO2 max) will be done. This test will be conducted on a stationary bicycle and the resistance will be gradually increased while the expired air is measured during exhaustive physical work. The test will last approximately 30 minutes. A mouthpiece with a one way re-breathing valve attached to a breathing tube will be used to collect air samples during the exercise test. Essentially, subjects will breathe room air through a mouthpiece, and then expire the air into a tube that connects to a machine (metabolic cart). This machine analyzes carbon dioxide and oxygen content, which allows us to calculate the amount of oxygen they are using under resting and exercise conditions.
The workload will be gradually increased on the bike by increasing the resistance. As the workload increases, oxygen consumption also increases. Throughout the test period exhaled air will be collected. When subjects can no longer continue, the test will be stopped. Blood pressure will be measured at the end of each resistance-stage. Heart rate data will be recorded continuously.
Before and after completing the exercise test, subjects will be required to complete a "warm-up" and "cool-down" session including stretching exercises.
Study design
- Primary purpose
- Screening
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| All participants | Other | Other: Autonomic Function Testing, Other: Posture Study, Procedure: Measurement of Total Blood Volume, Other: Exercise Capacity TestAll participants will be administered all procedures as described previously. Interventions: Autonomic Function Testing, Posture Study ,Measurement of Total Blood Volume ,Exercise Capacity Test |
Who may qualify
- Ages
- 18 to 50 years
- Sex
- Female only
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Age between 18-50 years old
- Patients with suspected POTS and healthy volunteers
- Sedentary healthy subjects of similar age and gender than patients will also be recruited.
- Only female participants are eligible.
- Able and willing to provide informed consent
Key exclusion criteria (9 listed)
- Smokers
- Overt cause for postural tachycardia, i.e., acute dehydration
- Significant cardiovascular, pulmonary, hepatic, or hematological disease by history or prior testing
- Highly trained athletes
- Subjects with somatization or severe anxiety symptoms will be excluded
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Autonomic Function Testingheart rate and blood pressure will be continuously monitored while participants undergo a variety of breathing techniques (deep breathing, rapid breathing, blowing against resistance) and during sustained handgrip and cold pressor (hand in ice water). All tests are meant to stimulate the autonomic nervous system to produce changes in blood pressure and heart rate of short duration that reflect how well the autonomic nervous system is functioning. Also during autonomic function testing, cardiac output will be measured to analyze the shift of fluids in the body (body impedance) and / or by analyzing the air that is breathed. | Other | All participants |
| Posture StudyAlso: Supine & standing blood pressure, heart rate & blood draws.Blood pressure, heart rate and blood samples (for catecholamines and hormones) will be measured \& collected in the supine (lying) and upright position for each participant. | Other | All participants |
| Measurement of Total Blood VolumeAlso: blood sample at baseline and at 12 minutes, I-131 is administered.Total blood volume is measured by using iodinated I-131 tagged human serum albumin. | Procedure or surgery | All participants |
| Exercise Capacity TestAlso: Masimal Oxygen Consumption TestParticipants will ride on a stationary recumbent bicycle and the resistance will be gradually increased while expired air is measured. | Other | All participants |
Primary outcome
blood volume deviation (%) from individual predicted volumes
Time frame: 2 days
Compare blood volume deviations using the 131-I-Albumin method. Deviations will be reported as a percentage deviation from an individual's predicted value. These values will be compared between POTS patients and healthy control groups.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 13 Jan 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Alfredo J Gamboa, MD principal investigator
Vanderbilt University Medical Center
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Autonomic Function Testing, Posture Study and Measurement of Total Blood Volume in people with Postural Tachycardia Syndrome, run by Vanderbilt University at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 9 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 13 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
blood volume deviation (%) from individual predicted volumes (time frame: 2 days). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 13 Jan 2026.