Diagnosing Postural Orthostatic Tachycardia Syndrome (POTS)
What is postural orthostatic tachycardia syndrome?
Postural orthostatic tachycardia syndrome (POTS) is a type of dysautonomia (an umbrella term for health conditions that affect the functioning of the autonomic nervous system). POTS is characterized by reduced blood circulation when standing upright from a reclined position. The blood pools in the lower extremities of the body, which results in reduced blood flow to the heart and brain. Reduced blood flow causes the heart rate to rapidly increase. With POTS syndrome, the heart rate increases at least 30 beats per minute in adults and at least 40 beats per minute in adolescents during the first 10 minutes of standing.
POTS is difficult to diagnose due to the differing symptoms experienced by each person with the condition. Because POTS shares symptoms with various other medical conditions, a proper diagnosis of POTS may take months or even years. It is important to find a physician with in-depth knowledge about the condition in order to obtain a proper diagnosis.
- The tilt table test is the preferred diagnostic test for POTS. During this test, the individual lies down on a table, and straps are placed on the body for stabilization and safety purposes. The test begins with the body in a horizontal position, and the table slowly moves to a vertical position, eventually placing the individual in an upright position. A health care professional closely monitors heart rate and blood pressure as the table position changes. Although fainting may occur, the individual is safely strapped to the tilt table, so there is no risk of falling. The tilt table test is a safe and effective way to diagnose POTS.
- Blood and urine tests can help identify the cause of POTS and eliminate the possibility of other conditions that mimic the symptoms of POTS.
- A quantitative sudomotor axon reflex test (QSART) measures the autonomic nerves that control sweating. This test requires mild electrical stimulation on the skin.
- An autonomic breathing test measures the rise and fall of blood pressure and volume during exercise.
- A skin nerve biopsy may be performed to evaluate small nerve fibers. This test is relatively painless and safe.
- Other tests that may be performed include a tuberculin skin test, echocardiogram, or blood volume with hemodynamic studies.