Dietary Salt in Postural Tachycardia Syndrome

we will measure the amount of hemoglobin and myoglobin in the body by a procedure called CO rebreathing. One teaspoon of blood is taken before and after a small amount of CO has been absorbed into the bloodstream.

Using injection of iodinated I-131 tagged human serum albumin nominally 25 microcuries of radiation, blood samples are drawn before and 30 minutes after injection.

subjects breath 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.

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.