Postural Orthostatic Tachycardia Syndrome
Conditions
Keywords
Orthostatic Intolerance, Tachycardia, Orthostatic Hypotension, Sodium
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.
Detailed description
Study Day 1 * Start 150 mEq Na+/day diet (POTS patients as inpatients; healthy control subjects with Clinical Research Center(CRC)- provided outpatient diet); consume 1.5-2 liters of water per day * Start a 24hour (24hr) urine collection (for sodium (Na+), potassium (K+), creatinine (Cr), fractionated catecholamines) * Blood work Study Days 2-5 * Continue 24hr urine collection * 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; consume 1.5-2 liters of water per day * On Day 5, a 24 hr Holter combined ECG monitor and BP monitor will be placed on the subjects. Study Day 6 * Continue STUDY DIET; consume 1.5-2 liters of water per day * Remove 24hr Holter combined ECG monitor and BP monitor from subject * Continue 24hr urine collection (for Na+, K+, Cr, fractionated catecholamines) * Admit to CRC in afternoon (healthy control subjects only, as POTS patients will have already been admitted). Each subject will spend the night in the CRC and remain supine * Nothing by mouth (NPO) after midnight for study next day Study Day 7 * Awaken early (\ 6am) to void (still collecting 24hr urine) * Patient returns to bed, IV catheter inserted * Posture Study (in morning; between 7-8am ideally) * Blood pressure and heart rate will be measured while supine and then while standing for up to 30 minutes * We will draw blood in each body position to measure electrolytes and hormones that regulate blood pressure and blood volume * Subjects will rate symptoms during supine period and at end of stand using Vanderbilt Orthostatic Symptoms Score (VOSS) * Total Blood Volume (DAXOR)- using injection of iodinated I-131 tagged human serum albumin nominally 25 micro-Ci of radiation blood samples drawn through IV catheter before injection and for \ 30 minutes post-injection (total - 25 ml) * This will be done after supine assessment, but before standing the subject up * Exercise Capacity Test (in the afternoon) Will estimate maximal oxygen consumption (VO2 max). This test will be conducted on a stationary bicycle. Effort will be gradually increased while expired air is measured during exhaustive physical work. All procedures are repeated at least a month later with the 2nd level of dietary salt. (Randomized to high or low salt in the first phase, the second phase is the remaining level)
Interventions
RADIATIONPlasma Volume
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.
PROCEDUREExercise Capacity Test - Bicycle
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.
PROCEDUREPosture 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
National Heart, Lung, and Blood Institute (NHLBI)
Vanderbilt University Medical Center
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
NONE
Intervention model description
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.
Eligibility
Sex/Gender
FEMALE
Age
18 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
* 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
Exclusion criteria
* 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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| 24hr Urinary Sodium | Day 6 am - Day 7 am for each dietary sodium level | Amount of sodium excreted in urine over 24hr ending on Day 7 |
| 24hr Urinary Dopamine | Between Day 6 am - Day 7 am of each dietary sodium level | Amount of dopamine excreted in urine over 24 hours ending on Day 7 |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Upright Symptom Score | Upright symptoms were assessed on the 6th day of low or high sodium diet. | Whether upright symptoms were improved in patients with POTS on a High Sodium diet relative to a Low Sodium diet. Patients were asked to report their standing symptom burden at the end of the Stand portion of the posture study, using the Vanderbilt Orthostatic Symptoms Scale (VOSS). They rated the severity of nine symptoms (palpitations, lightheadedness, mental confusion, blurred vision, shortness of breath, tremulousness, chest discomfort, headache, and nausea) on a scale ranging from a minimum of 0 (reflecting an absence of symptoms) to a maximum score of 10. The sum of the individual symptom scores was used to calculate orthostatic symptom burden for each participant. The lowest possible total score was 0, if a participant scored all 9 questions as 0, and the highest possible score was 90, if a participant scored all 9 questions as 10. Higher scores indicated worse symptoms. |
| Urinary Sodium Following Change in Dietary Sodium Days 1-2 | 24 hour collections ending on Day 2 of each diet phase | Urinary sodium excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets. |
| Urinary Dopamine Following Change in Dietary Sodium Days1-2 | 24 hour collections ending on Day 2 of each dietary sodium phase | Urinary dopamine excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets. |
| Urinary Sodium Following Change in Dietary Sodium Days 2-3 | 24 hour collections ending on Day 3 of each diet phase | Urinary sodium excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets. |
| Urinary Sodium Following Change in Dietary Sodium Days 3-4 | 24 hour collections ending on Day 4 of each diet phase | Urinary sodium excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets. |
| Plasma Volume | after 7 days of each dietary sodium level | Plasma volume (PV) was determined by the indicator tracer-dilution technique, using the DAXOR Blood Volume Analyzer (BVA)-100 system (DAXOR Corporation), on Day 7 of the low sodium and high sodium dietary interventions. |
| Urinary Sodium Following Change in Dietary Sodium Days 5-6 | 24 hour collections ending on Day 6 of each diet phase | Urinary sodium excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets. |
| Urinary Dopamine Following Change in Dietary Sodium Days 2-3 | 24 hour collections ending on Day 3 of each dietary sodium phase | Urinary dopamine excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets. |
| Urinary Dopamine Following Change in Dietary Sodium Days 3-4 | 24 hour collections ending on Day 4 of each dietary sodium phase | Urinary dopamine excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets. |
| Urinary Dopamine Following Change in Dietary Sodium Days 4-5 | 24 hour collections ending on Day 5 of each dietary sodium phase | Urinary dopamine excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets. |
| Urinary Dopamine Following Change in Dietary Sodium Days 5-6 | 24 hour collections ending on Day 6 of each dietary sodium phase | Urinary dopamine excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets. |
| Urinary Sodium Following Change in Dietary Sodium Days 4-5 | 24 hour collections ending on Day 5 of each diet phase | Urinary sodium excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets |
| Magnitude of Orthostatic Tachycardia | Supine and upright heart rate were measured after 6 days of each dietary sodium level | Whether the magnitude of the heart rate increase that occurs in patients with POTS when moving from a supine to an upright position is attenuated by a High Sodium diet relative to a Low Sodium diet. Heart rate was assessed after overnight rest and fasting after midnight, following at least 60 minutes of lying quietly. Heart rate was then measured at intervals after subjects had been standing for up to 30 minutes (as tolerated). Differences between supine and standing values are presented for 5 minutes standing (or maximal stand if \<5 minutes) since several patients were unable to stand for 10 minutes. Data in POTS patients were compared to that of Healthy Controls. |
Countries
United States
Participant flow
Pre-assignment details
Healthy Participants: 17 were enrolled and randomized. 1 withdrew due to scheduling. 1 withdrew with migraines in phase 1 (low Na+). 2 withdrew in phase 1 (high Na+): 1 unable to tolerate study diet and another had difficulty cooperating with investigators. Postural Tachycardia Syndrome (POTS): 21 were enrolled and randomized. 6 withdrew before baseline due to age (1), pregnancy (1), prohibited meds (3), and scheduling (1). A 7th patient withdrew during phase 1 (high Na+) due to family illness.
Participants by arm
| Arm | Count |
|---|---|
| Healthy Participants-Low Na+ Then High Na+ Healthy controls were randomly assigned the order of dietary sodium (Na+) levels. After 1 day on diet with 150 mEq sodium/day, participants consumed low Na+ diet (10 mEq sodium/day; LS) for 6 days followed in at least 1 month by 1 day of 150 mEq sodium/day and 6 days of high Na+ diet (300 mEq sodium/day; HS). All procedures were performed at both levels | 11 |
| HealthyParticipants-HighNa+ Then Low Na+ Healthy controls were randomly assigned the order of dietary sodium (Na+) levels. After 1 day on diet with 150 mEq sodium/day, participants consumed high Na+ diet (300 mEq sodium/day; HS) for 6 days followed in at least 1 month by 1 day of 150 mEq sodium/day and 6 days of low Na+ diet (10 mEq sodium/day; LS). All procedures were performed at both levels | 2 |
| Patients With POTS-Low Na+ Then High Na+ Patients with POTS were randomly assigned the order of dietary sodium (Na+) levels. After 1 day on diet with 150 mEq sodium/day, participants consumed low Na+ diet (10 mEq sodium/day; LS) for 6 days followed in at least 1 month by 1 day of 150 mEq sodium/day and 6 days of high Na+ diet (300 mEq sodium/day; HS). All procedures were performed at both levels | 8 |
| Patients With POTS-High Na+ Then Low Na+ Patients with POTS were randomly assigned the order of dietary sodium (Na+) levels. After 1 day on diet with 150 mEq sodium/day, participants consumed high Na+ diet (300 mEq sodium/day; HS) for 6 days followed in at least 1 month by 1 day of 150 mEq sodium/day and 6 days of low Na+ diet (10 mEq sodium/day; LS). All procedures were performed at both levels | 6 |
| Total | 27 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 | FG002 | FG003 |
|---|---|---|---|---|---|
| Overall Study | Physician Decision | 0 | 1 | 1 | 3 |
| Overall Study | Withdrawal by Subject | 1 | 2 | 1 | 2 |
Baseline characteristics
| Characteristic | Healthy Participants-Low Na+ Then High Na+ | Total | Patients With POTS-High Na+ Then Low Na+ | Patients With POTS-Low Na+ Then High Na+ | HealthyParticipants-HighNa+ Then Low Na+ |
|---|---|---|---|---|---|
| Age, Continuous | 31 years STANDARD_DEVIATION 6 | 33 years STANDARD_DEVIATION 7 | 32 years STANDARD_DEVIATION 6 | 36 years STANDARD_DEVIATION 9 | 35 years STANDARD_DEVIATION 10 |
| Ethnicity (NIH/OMB) Hispanic or Latino | 1 Participants | 2 Participants | 1 Participants | 0 Participants | 0 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 10 Participants | 25 Participants | 5 Participants | 8 Participants | 2 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Asian | 1 Participants | 1 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Black or African American | 1 Participants | 1 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) More than one race | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) White | 9 Participants | 25 Participants | 6 Participants | 8 Participants | 2 Participants |
| Region of Enrollment United States | 11 participants | 27 participants | 6 participants | 8 participants | 2 participants |
| Sex: Female, Male Female | 11 Participants | 27 Participants | 6 Participants | 8 Participants | 2 Participants |
| Sex: Female, Male Male | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk | EG003 affected / at risk |
|---|---|---|---|---|
| deaths Total, all-cause mortality | 0 / 13 | 0 / 13 | 0 / 14 | 0 / 14 |
| other Total, other adverse events | 0 / 13 | 1 / 13 | 0 / 14 | 0 / 14 |
| serious Total, serious adverse events | 0 / 13 | 0 / 13 | 0 / 14 | 0 / 14 |
Outcome results
Primary
24hr Urinary Dopamine
Amount of dopamine excreted in urine over 24 hours ending on Day 7
Time frame: Between Day 6 am - Day 7 am of each dietary sodium level
Population: 24hr urine samples ending on Day 7 were collected for 13 healthy controls and 14 patients with POTS
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Healthy Participants Who Consumed Low Sodium Diet as Intervention A or Intervention B | 24hr Urinary Dopamine | 223 micrograms |
| Healthy Participants Who Consumed High Sodium Diet as Intervention A or Intervention B | 24hr Urinary Dopamine | 236 micrograms |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed Low Sodium Diet. | 24hr Urinary Dopamine | 202 micrograms |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed High Sodium Diet | 24hr Urinary Dopamine | 205 micrograms |
Primary
24hr Urinary Sodium
Amount of sodium excreted in urine over 24hr ending on Day 7
Time frame: Day 6 am - Day 7 am for each dietary sodium level
Population: 24hr urine samples ending on Day 7 were collected for 13 healthy controls and 14 patients with POTS
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Healthy Participants Who Consumed Low Sodium Diet as Intervention A or Intervention B | 24hr Urinary Sodium | 16.8 milliequivalents |
| Healthy Participants Who Consumed High Sodium Diet as Intervention A or Intervention B | 24hr Urinary Sodium | 280 milliequivalents |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed Low Sodium Diet. | 24hr Urinary Sodium | 14.7 milliequivalents |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed High Sodium Diet | 24hr Urinary Sodium | 245 milliequivalents |
Secondary
Magnitude of Orthostatic Tachycardia
Whether the magnitude of the heart rate increase that occurs in patients with POTS when moving from a supine to an upright position is attenuated by a High Sodium diet relative to a Low Sodium diet. Heart rate was assessed after overnight rest and fasting after midnight, following at least 60 minutes of lying quietly. Heart rate was then measured at intervals after subjects had been standing for up to 30 minutes (as tolerated). Differences between supine and standing values are presented for 5 minutes standing (or maximal stand if \<5 minutes) since several patients were unable to stand for 10 minutes. Data in POTS patients were compared to that of Healthy Controls.
Time frame: Supine and upright heart rate were measured after 6 days of each dietary sodium level
Population: Data is not included for 1 patient with POTS on a Low Sodium diet since that patient was unable to stand for even 1 minute.
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Healthy Participants Who Consumed Low Sodium Diet as Intervention A or Intervention B | Magnitude of Orthostatic Tachycardia | 23 beats per minute |
| Healthy Participants Who Consumed High Sodium Diet as Intervention A or Intervention B | Magnitude of Orthostatic Tachycardia | 19 beats per minute |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed Low Sodium Diet. | Magnitude of Orthostatic Tachycardia | 60 beats per minute |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed High Sodium Diet | Magnitude of Orthostatic Tachycardia | 46 beats per minute |
Secondary
Plasma Volume
Plasma volume (PV) was determined by the indicator tracer-dilution technique, using the DAXOR Blood Volume Analyzer (BVA)-100 system (DAXOR Corporation), on Day 7 of the low sodium and high sodium dietary interventions.
Time frame: after 7 days of each dietary sodium level
Population: No data analysis for 1 healthy control who had poor venous access on Day 7 of the high sodium diet.
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Healthy Participants Who Consumed Low Sodium Diet as Intervention A or Intervention B | Plasma Volume | 2805 mL |
| Healthy Participants Who Consumed High Sodium Diet as Intervention A or Intervention B | Plasma Volume | 3032 mL |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed Low Sodium Diet. | Plasma Volume | 2362 mL |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed High Sodium Diet | Plasma Volume | 2633 mL |
Secondary
Upright Symptom Score
Whether upright symptoms were improved in patients with POTS on a High Sodium diet relative to a Low Sodium diet. Patients were asked to report their standing symptom burden at the end of the Stand portion of the posture study, using the Vanderbilt Orthostatic Symptoms Scale (VOSS). They rated the severity of nine symptoms (palpitations, lightheadedness, mental confusion, blurred vision, shortness of breath, tremulousness, chest discomfort, headache, and nausea) on a scale ranging from a minimum of 0 (reflecting an absence of symptoms) to a maximum score of 10. The sum of the individual symptom scores was used to calculate orthostatic symptom burden for each participant. The lowest possible total score was 0, if a participant scored all 9 questions as 0, and the highest possible score was 90, if a participant scored all 9 questions as 10. Higher scores indicated worse symptoms.
Time frame: Upright symptoms were assessed on the 6th day of low or high sodium diet.
Population: Upright symptom scores were inadvertently not obtained for the following number of participants:~Healthy Participants on Low Sodium diet: 3 Healthy Participants on High Sodium diet: 2 Patients with POTS on Low Sodium diet: 5 Patients with POTS on High Sodium diet: 6
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Healthy Participants Who Consumed Low Sodium Diet as Intervention A or Intervention B | Upright Symptom Score | 1 score on a scale |
| Healthy Participants Who Consumed High Sodium Diet as Intervention A or Intervention B | Upright Symptom Score | 0 score on a scale |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed Low Sodium Diet. | Upright Symptom Score | 30 score on a scale |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed High Sodium Diet | Upright Symptom Score | 19 score on a scale |
Secondary
Urinary Dopamine Following Change in Dietary Sodium Days1-2
Urinary dopamine excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets.
Time frame: 24 hour collections ending on Day 2 of each dietary sodium phase
Population: One healthy control neglected to collect urine during this time interval on the low sodium diet
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Healthy Participants Who Consumed Low Sodium Diet as Intervention A or Intervention B | Urinary Dopamine Following Change in Dietary Sodium Days1-2 | 228 micrograms |
| Healthy Participants Who Consumed High Sodium Diet as Intervention A or Intervention B | Urinary Dopamine Following Change in Dietary Sodium Days1-2 | 200 micrograms |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed Low Sodium Diet. | Urinary Dopamine Following Change in Dietary Sodium Days1-2 | 207 micrograms |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed High Sodium Diet | Urinary Dopamine Following Change in Dietary Sodium Days1-2 | 202 micrograms |
Secondary
Urinary Dopamine Following Change in Dietary Sodium Days 2-3
Urinary dopamine excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets.
Time frame: 24 hour collections ending on Day 3 of each dietary sodium phase
Population: The urine sample for 1 healthy control was collected during this interval of the low sodium diet phase, but the sample was inadvertently sent to the wrong lab for analysis
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Healthy Participants Who Consumed Low Sodium Diet as Intervention A or Intervention B | Urinary Dopamine Following Change in Dietary Sodium Days 2-3 | 183 micrograms |
| Healthy Participants Who Consumed High Sodium Diet as Intervention A or Intervention B | Urinary Dopamine Following Change in Dietary Sodium Days 2-3 | 185 micrograms |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed Low Sodium Diet. | Urinary Dopamine Following Change in Dietary Sodium Days 2-3 | 205 micrograms |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed High Sodium Diet | Urinary Dopamine Following Change in Dietary Sodium Days 2-3 | 171 micrograms |
Secondary
Urinary Dopamine Following Change in Dietary Sodium Days 3-4
Urinary dopamine excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets.
Time frame: 24 hour collections ending on Day 4 of each dietary sodium phase
Population: The urine sample for 1 healthy control was collected during this interval of the low sodium diet phase, but the sample was inadvertently sent to the wrong lab for analysis
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Healthy Participants Who Consumed Low Sodium Diet as Intervention A or Intervention B | Urinary Dopamine Following Change in Dietary Sodium Days 3-4 | 222 micrograms |
| Healthy Participants Who Consumed High Sodium Diet as Intervention A or Intervention B | Urinary Dopamine Following Change in Dietary Sodium Days 3-4 | 193 micrograms |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed Low Sodium Diet. | Urinary Dopamine Following Change in Dietary Sodium Days 3-4 | 203 micrograms |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed High Sodium Diet | Urinary Dopamine Following Change in Dietary Sodium Days 3-4 | 177 micrograms |
Secondary
Urinary Dopamine Following Change in Dietary Sodium Days 4-5
Urinary dopamine excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets.
Time frame: 24 hour collections ending on Day 5 of each dietary sodium phase
Population: Urine was collected and analyzed for 13 healthy controls and 14 patients with POTS during this time interval of the low sodium and high sodium diets
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Healthy Participants Who Consumed Low Sodium Diet as Intervention A or Intervention B | Urinary Dopamine Following Change in Dietary Sodium Days 4-5 | 213 micrograms |
| Healthy Participants Who Consumed High Sodium Diet as Intervention A or Intervention B | Urinary Dopamine Following Change in Dietary Sodium Days 4-5 | 202 micrograms |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed Low Sodium Diet. | Urinary Dopamine Following Change in Dietary Sodium Days 4-5 | 205 micrograms |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed High Sodium Diet | Urinary Dopamine Following Change in Dietary Sodium Days 4-5 | 214 micrograms |
Secondary
Urinary Dopamine Following Change in Dietary Sodium Days 5-6
Urinary dopamine excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets.
Time frame: 24 hour collections ending on Day 6 of each dietary sodium phase
Population: Urine was collected and analyzed for 13 healthy controls and 14 patients with POTS during this time interval of the low sodium and high sodium diets
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Healthy Participants Who Consumed Low Sodium Diet as Intervention A or Intervention B | Urinary Dopamine Following Change in Dietary Sodium Days 5-6 | 227 micrograms |
| Healthy Participants Who Consumed High Sodium Diet as Intervention A or Intervention B | Urinary Dopamine Following Change in Dietary Sodium Days 5-6 | 210 micrograms |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed Low Sodium Diet. | Urinary Dopamine Following Change in Dietary Sodium Days 5-6 | 211 micrograms |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed High Sodium Diet | Urinary Dopamine Following Change in Dietary Sodium Days 5-6 | 199 micrograms |
Secondary
Urinary Sodium Following Change in Dietary Sodium Days 1-2
Urinary sodium excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets.
Time frame: 24 hour collections ending on Day 2 of each diet phase
Population: One healthy control neglected to collect urine during this time interval on low sodium diet, and a urine sample for another healthy control on high sodium diet was inadvertently not analyzed for sodium
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Healthy Participants Who Consumed Low Sodium Diet as Intervention A or Intervention B | Urinary Sodium Following Change in Dietary Sodium Days 1-2 | 145 milliequivalents |
| Healthy Participants Who Consumed High Sodium Diet as Intervention A or Intervention B | Urinary Sodium Following Change in Dietary Sodium Days 1-2 | 134 milliequivalents |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed Low Sodium Diet. | Urinary Sodium Following Change in Dietary Sodium Days 1-2 | 143 milliequivalents |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed High Sodium Diet | Urinary Sodium Following Change in Dietary Sodium Days 1-2 | 160 milliequivalents |
Secondary
Urinary Sodium Following Change in Dietary Sodium Days 2-3
Urinary sodium excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets.
Time frame: 24 hour collections ending on Day 3 of each diet phase
Population: 24hr urine samples were collected and analyzed for 13 healthy controls and 14 patients with POTS during both the low sodium and high sodium diet phases
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Healthy Participants Who Consumed Low Sodium Diet as Intervention A or Intervention B | Urinary Sodium Following Change in Dietary Sodium Days 2-3 | 88.0 milliequivalents |
| Healthy Participants Who Consumed High Sodium Diet as Intervention A or Intervention B | Urinary Sodium Following Change in Dietary Sodium Days 2-3 | 199 milliequivalents |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed Low Sodium Diet. | Urinary Sodium Following Change in Dietary Sodium Days 2-3 | 70.1 milliequivalents |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed High Sodium Diet | Urinary Sodium Following Change in Dietary Sodium Days 2-3 | 154 milliequivalents |
Secondary
Urinary Sodium Following Change in Dietary Sodium Days 3-4
Urinary sodium excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets.
Time frame: 24 hour collections ending on Day 4 of each diet phase
Population: 24hr urine samples were collected and analyzed for 13 healthy controls and 14 patients with POTS during both the low sodium and high sodium diet phases
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Healthy Participants Who Consumed Low Sodium Diet as Intervention A or Intervention B | Urinary Sodium Following Change in Dietary Sodium Days 3-4 | 32.7 milliequivalents |
| Healthy Participants Who Consumed High Sodium Diet as Intervention A or Intervention B | Urinary Sodium Following Change in Dietary Sodium Days 3-4 | 230 milliequivalents |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed Low Sodium Diet. | Urinary Sodium Following Change in Dietary Sodium Days 3-4 | 28.9 milliequivalents |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed High Sodium Diet | Urinary Sodium Following Change in Dietary Sodium Days 3-4 | 222 milliequivalents |
Secondary
Urinary Sodium Following Change in Dietary Sodium Days 4-5
Urinary sodium excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets
Time frame: 24 hour collections ending on Day 5 of each diet phase
Population: The urine sample for 1 patient with POTS was collected during this time interval during high sodium diet but it was inadvertently not analyzed.
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Healthy Participants Who Consumed Low Sodium Diet as Intervention A or Intervention B | Urinary Sodium Following Change in Dietary Sodium Days 4-5 | 17.3 milliequivalents |
| Healthy Participants Who Consumed High Sodium Diet as Intervention A or Intervention B | Urinary Sodium Following Change in Dietary Sodium Days 4-5 | 216 milliequivalents |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed Low Sodium Diet. | Urinary Sodium Following Change in Dietary Sodium Days 4-5 | 21.6 milliequivalents |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed High Sodium Diet | Urinary Sodium Following Change in Dietary Sodium Days 4-5 | 264 milliequivalents |
Secondary
Urinary Sodium Following Change in Dietary Sodium Days 5-6
Urinary sodium excretion will be measured every 24 hours as the participant adapts from the 150 mEq Na/day diet to the 10 and 300 mEq Na/day diets.
Time frame: 24 hour collections ending on Day 6 of each diet phase
Population: 24hr urine samples were collected and analyzed for 13 healthy controls and 14 patients with POTS during both the low sodium and high sodium diet phases
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Healthy Participants Who Consumed Low Sodium Diet as Intervention A or Intervention B | Urinary Sodium Following Change in Dietary Sodium Days 5-6 | 21.6 milliequivalents |
| Healthy Participants Who Consumed High Sodium Diet as Intervention A or Intervention B | Urinary Sodium Following Change in Dietary Sodium Days 5-6 | 260 milliequivalents |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed Low Sodium Diet. | Urinary Sodium Following Change in Dietary Sodium Days 5-6 | 18.2 milliequivalents |
| Postural Tachycardia Syndrome (POTS) Participants Who Consumed High Sodium Diet | Urinary Sodium Following Change in Dietary Sodium Days 5-6 | 242 milliequivalents |