POTS Adrenergic Ab (CIHR Aims #1&2)

Inclusion Criteria: * Patients who have been previously diagnosed with POTS * Control subjects (patients not diagnosed with POTS) * Age between 18 - 60 years * Males and Females (Give that \>80% of POTS patients are female, we will attempt to enroll a similar percentage of female control subjects) * Able and willing to provide consent Exclusion Criteria: * 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 * Use of drospirenone (a spironolactone analogue) containing oral contraceptive agent * 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