Quantitative Sudomotor Axon Reflex Test


How to say it: Kwan-tit-tay-tiv Soo-do-mo-tore Reflex Test


The Quantitative Sudomotor Axon Reflex Test (QSART) measures how well the nerves that control sweating are working.

Reasons for Procedure

QSART may be done to diagnose or assess:

Possible Complications

Problems from the test are rare.

What to Expect

Prior to Test

  • Do not eat or drink anything with caffeine or smoke 4 hours before the test.
  • Do not drink anything with alcohol for 12 to 14 hours before the test.
  • Talk to your doctor if you take any medicines, herbs, or supplements.

Certain medications may interfere with the test. These medications may need to be stopped up to 1 week before the procedure. Talk to your doctor before the procedure about all medications you are taking.


Anesthesia will not be needed. The test does not cause pain, just a mild burning or discomfort.

Description of the Procedure

The skin on the leg and wrist will be cleaned. Three electrodes filled with a chemical will be placed on the leg and 1 electrode will be placed on the wrist. A mild electrical current will be applied to help the chemical stimulate the sweat glands. The sweat response is measured.

How Long Will It Take?

2 to 3 hours

Will It Hurt?

A mild burning sensation may be felt at the electrode during the test.

Post-procedure Care

At the Care Center

Right after the procedure, the electrodes will be removed and your skin will be cleaned. You will be able to leave after the procedure.

It may take 3 days or longer to receive the results of your test, depending on where the data is analyzed.

Call Your Doctor

Call your doctor if you have a rash at the electrode site.

If you think you have an emergency, call for emergency medical services right away.


Department of Neurology—University of Pittsburgh

The Foundation for Peripheral Neuropathy

Canadian Resources:

Canadian Decompression and Neuropathy Center

Health Canada


Electrodiagnostic testing: Nerve Conduction Studies and Electromyography (EMG). Department of Neurology—University of Pittsburgh website. Available at: http://www.neurology.upmc.edu/neuromuscular/patient_info/testing.html. Accessed July 17, 2020.

QSART testing. Vanderbilt Autonomic Dysfunction Center website. Available at: https://ww2.mc.vanderbilt.edu/adc/38922. Accessed July 17, 2020.

Quantitative sudomotor axon reflex test. The Foundation for Peripheral Neuropathy website. Available at: https://www.foundationforpn.org/what-is-peripheral-neuropathy/evaluation-and-tests/quantitative-sudomotor-axon-reflex-test/. Accessed July 17, 2020.

Quantitative sudomotor axon reflex test (QSART). Cleveland Clinic website. Available at: https://my.clevelandclinic.org/health/articles/qsart. Accessed July 17, 2020.

Last reviewed July 2020 by EBSCO Medical Review Board Dr. Lukas Rimas, MD  Last Updated: 7/17/2020