Dietary Sodium's Effect on Urinary Sodium and Dopamine Excretion in Patients With Postural Tachycardia Syndrome
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 38
- 试验地点
- 2
- 主要终点
- 24hr Urinary Sodium
研究概览
简要总结
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.
详细描述
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
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Crossover
- 主要目的
- Basic Science
- 盲法
- None
入排标准
- 年龄范围
- 18 Years 至 50 Years（Adult）
- 性别
- Female
- 接受健康志愿者
- 是
入选标准
- •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
排除标准
- •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
结局指标
主要结局
24hr Urinary Sodium
时间窗: 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
时间窗: 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
次要结局
- 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 3-4(24 hour collections ending on Day 4 of each diet phase)
- Urinary Sodium Following Change in Dietary Sodium Days 4-5(24 hour collections ending on Day 5 of each diet phase)
- Urinary Dopamine Following Change in Dietary Sodium Days 4-5(24 hour collections ending on Day 5 of each dietary sodium phase)
- Urinary Dopamine Following Change in Dietary Sodium Days 5-6(24 hour collections ending on Day 6 of each dietary sodium phase)
- Urinary Sodium Following Change in Dietary Sodium Days 2-3(24 hour collections ending on Day 3 of each diet phase)
- Urinary Sodium Following Change in Dietary Sodium Days 5-6(24 hour collections ending on Day 6 of each diet phase)
- Urinary Dopamine Following Change in Dietary Sodium Days 3-4(24 hour collections ending on Day 4 of each dietary sodium phase)
- 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)
- 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)
- Urinary Dopamine Following Change in Dietary Sodium Days 2-3(24 hour collections ending on Day 3 of each dietary sodium phase)
研究者
Alfredo Gamboa
Associate Professor
Vanderbilt University Medical Center