Overview

What is the quantitative sudomotor axon reflex test (QSART)?

The quantitative sudomotor axon reflex test (QSART, or sweat test) measures the nerves that control sweating. The test can help diagnose autonomic nervous system disorders, peripheral neuropathies and some types of pain disorders. The autonomic nervous system controls the working of your body’s internal organs, which includes regulating body temperature, blood pressure, heart rate and digestion.

The test involves a mild electrical stimulation on the skin called iontophoresis, which allows acetylcholine, a naturally occurring chemical, to stimulate your sweat glands. The QSART measures the volume of sweat produced by this stimulation.

Test Details

Can I eat or drink before the quantitative sudomotor axon reflex test (QSART)?

You can eat a light meal. However:

Don’t eat or drink anything with caffeine, or smoke four hours before the test.
Don’t drink anything with alcohol for 12 to 14 hours prior to the test.

What medications can I take before the QSART?

Some medications can interfere with the test. Make sure your provider knows all the medications you’re taking.

Don’t take any over-the-counter cold or cough medications, aspirin, antihistamines, antidepressants or diuretics 48 hours before the test.

What should I expect during the QSART?

Please come to the test room wearing loose clothing. You’ll be asked to remove your shoes and socks, including compression stockings. The technician will discuss the steps of the test and answer any questions you may have. Then:

The technician will wipe the skin on your foot, leg and wrist with acetone.
Four electrodes filled with acetylcholine are then placed on three areas of the leg and one on the wrist.
The iontophoretic stimulators are turned on, and sweat responses are measured.

The test takes approximately 45 minutes to one hour. A mild burning discomfort may be experienced at the site of stimulation during the test.

Results and Follow-Up

What happens after the quantitative sudomotor axon reflex test (QSART)?

Your data is collected by the technician, and the final report is sent to the provider who referred you for the test. Within a few days your provider will provide you with the results. Different clinics may have different procedures. Ask your provider for details on your test results and follow-up.

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Quantitative Sudomotor Axon Reflex Test (QSART)