Autonomic Testing
Reviewed
Also called: Autonomic Testing, tilt table test, quantitative sudomotor axon reflex test, QSART, thermoregulatory sweat test, TST
Autonomic testing helps find out if your autonomic nervous system (ANS) is working as well as it should.
Specimen: Not applicable (no laboratory specimen; the tests are performed on the body directly)
Why this test may be ordered
- To check for problems with the autonomic nervous system (ANS).
- To evaluate symptoms of autonomic neuropathy, such as dizziness, fainting, abnormal heart rate or blood pressure, digestive issues, bladder problems, sweating abnormalities, sexual dysfunction, or difficulty adjusting to light changes.
- To help determine which part of the ANS is affected and how severe the problem is.
Preparation and collection
Your provider will give you specific instructions on how to prepare, but many autonomic tests require the following preparations: Don't eat or drink anything with caffeine for eight hours before your test. Keep well hydrated with noncaffeinated beverages the day before your test. Don't drink alcohol for 12 hours before your test. Don't smoke or use tobacco products for four hours before your test. Check with your provider about how to prepare for your test. They will also let you know if you need to stop taking any medicines before your test.
There are different types of autonomic tests. Depending on your symptoms, your provider may perform one or more of the following tests: Deep Breathing Test and Valsalva Maneuver. These tests measure your heart rate and blood pressure while doing certain types of breathing. This test measures your blood pressure and heart rate as you change your posture and position to find why you have had lightheadedness or fainted. If the test causes you to faint, the table will be quickly returned to the flat position.
Some people faint during a tilt table test. If that happens, you will immediately be tilted back to a normal position. During and after a tilt table test, you may experience nausea, vomiting, or weakness. Weakness may last a few hours, but other symptoms usually go away quickly. You may have some skin irritation from the electrodes used in a sweat test.
Understanding results
To make a diagnosis, your provider will also consider your medical history, symptoms, and results from your physical exam.
- Not normal: If any of your autonomic test results were not normal, it likely means that there is a problem with your ANS. Limitation: To make a diagnosis, your provider will also consider your medical history, symptoms, and results from your physical exam. Next step: Sometimes they will order more tests, especially if the cause of your ANS problem is unknown.
- Not normal, with another disease causing the problem: If another disease is causing your ANS problems, treating that disease may help. Limitation: Otherwise, treatment focuses on helping with your symptoms. Next step: This could include medicines and/or lifestyle changes.
- Physical risks: fainting, nausea, vomiting, weakness during tilt table test; skin irritation from electrodes in sweat tests.
- Emotional risks: possible anxiety during testing or from fainting episode.
- False positives/negatives: not explicitly stated, but results are interpreted in context of history and exam; abnormal results do not alone diagnose a condition.
- No specimen collection; no laboratory analysis involved.
What to do next
If you have questions about your results, talk to your provider.
- What symptoms led you to recommend autonomic testing?
- Which specific autonomic tests will I be having?
- How should I prepare for each test?
- Are there any medications I should stop before the test?
- What should I expect during and after the test? How long will it take? What are the possible risks? How will I get my results? When will they be available? Who will explain them to me? Will I need any follow-up tests? What happens if the results are abnormal? What treatment options are available if I have autonomic neuropathy? Are there lifestyle changes I can make to help manage my symptoms? Are there any support groups or resources for people with autonomic neuropathy?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.