If dysautonomia is suspected, you may hear terms like tilt table test, QSART, or autonomic reflex screen. Here’s what each test measures, what to expect, and why the results matter.
Bedside testing
Active stand test
You lie down for several minutes while heart rate and blood pressure are recorded, then stand for up to 10 minutes while measurements continue. It’s simple and often the first step in evaluating POTS and orthostatic hypotension. A version where you lean against a wall is sometimes called the NASA lean test.
Formal autonomic testing
These tests are performed at specialized autonomic labs, often within neurology or cardiology departments.
Tilt table test
You lie on a table that tilts you upright while heart rate and blood pressure are continuously monitored. It helps diagnose POTS, orthostatic hypotension, and vasovagal syncope, and can capture a fainting episode under controlled conditions.
Heart rate response to deep breathing
You breathe slowly and deeply while heart rate is recorded. A healthy vagus nerve causes heart rate to rise and fall with breathing. A reduced response suggests parasympathetic nerve dysfunction.
Valsalva maneuver
You blow against resistance for about 15 seconds. The heart rate and blood pressure pattern during and after shows how well the autonomic reflexes that control blood pressure are working.
QSART (quantitative sudomotor axon reflex test)
A mild electrical stimulus with a sweat-stimulating medication measures sweat output at several spots on the arm and leg. Reduced sweating can indicate small nerve fiber damage.
Thermoregulatory sweat test
You’re gently warmed while a powder that changes color with sweat shows which areas of skin sweat normally.
Skin biopsy for small fiber neuropathy
A tiny skin sample, usually from the lower leg, is examined to count small nerve fibers. It’s the standard test for small fiber neuropathy, which can cause burning pain and autonomic symptoms.
Preparing for testing
Testing centers usually provide instructions that may include:
- avoiding caffeine, nicotine, and heavy meals beforehand,
- wearing comfortable clothing, and
- holding certain medications. Only stop medications if the ordering clinician tells you to.
Why testing matters
Formal testing can:
- confirm the specific type of dysautonomia,
- identify nerve involvement,
- separate dysautonomia from heart rhythm problems, and
- document findings that help with ongoing care.
Not everyone needs every test. A careful history and bedside measurements often guide which tests, if any, will add useful information.
Serving Oklahoma City, Tulsa, and all of Oklahoma
Venturis Clinic sees patients from Oklahoma City and surrounding areas, including Tulsa, and from across Oklahoma, and helps coordinate formal autonomic testing when it’s needed. Learn more on our Dysautonomia in Oklahoma City page.
Frequently asked questions
Is a tilt table test painful?
No. It can reproduce symptoms like lightheadedness or fainting, which is part of what the test is designed to capture, and you’re monitored throughout.
Do I need a tilt table test to be diagnosed with POTS?
Not always. An active stand test is often sufficient, and a tilt table test may be recommended in some cases.
What does QSART show?
It measures sweat nerve function and can suggest small fiber nerve damage.
How long does autonomic testing take?
A full autonomic reflex screen often takes one to two hours. An active stand test takes about 15 to 20 minutes.
Wondering which tests make sense for you? Book a free 15-minute discovery call, or learn more about dysautonomia care in Oklahoma City.
This page is for educational purposes and is not a substitute for individual evaluation.
By Alvin Philipose, DC, ICCP
Sources
- Sheldon RS, et al. Heart Rhythm. 2015;12(6):e41–e63.
- Freeman R, et al. Clinical Autonomic Research. 2011;21(2):69–72.