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. The ANS controls body functions that happen automatically, such as breathing, heartbeat, body temperature, and digestion. If there are problems with the ANS, it is known as autonomic neuropathy. Autonomic testing can show which part of your ANS is affected and how seriously it's affected.
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
Follow your provider's specific instructions. Common preparations: avoid caffeine for 8 hours, stay well hydrated with noncaffeinated beverages the day before, avoid alcohol for 12 hours, and do not smoke or use tobacco for 4 hours before the test. Your provider may also ask you to stop certain medications.
Procedures
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. There are no known risks to having an ultrasound. You may have some skin irritation from the electrodes used in a sweat test.
Understanding results
Autonomic testing results are reviewed by your healthcare provider. They will consider your medical history, symptoms, and physical exam to interpret the findings. The following patterns are based on the test results.
- Normal: All autonomic test results are within normal limits. This suggests that your autonomic nervous system is functioning properly. Limitation: Normal results do not completely rule out autonomic neuropathy, as early or mild problems may not be detected. Next step: No further testing may be needed unless symptoms persist.
- Abnormal: One or more autonomic test results were not normal. This may indicate a problem with your autonomic nervous system (autonomic neuropathy). Your provider will use this information along with your history, symptoms, and physical exam to make a diagnosis. Limitation: Abnormal results do not by themselves confirm a specific diagnosis. They may be caused by many conditions, including diabetes, autoimmune diseases, certain medicines, or infections. Next step: Your provider may order additional tests to identify the underlying cause and develop a treatment plan.
- 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
Your healthcare provider will consider your medical history, symptoms, and physical exam alongside your test results. If results are abnormal, additional tests may be ordered to determine the cause of the autonomic nervous system problem.
- 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?