What is a QSART?

A QSART test, also called a quantitative sudomotor axon reflex test or sweat test, examines the nerves that govern sweating. During this test, electrical stimulation on your skin, generally termed iontophoresis, is applied. The QSART measures how much sweat this evokes.

What is the QSART test used for?

A QSART can aid in diagnosing conditions of the autonomic nervous system, peripheral neuropathies, and some kinds of pain disorders. The autonomic nervous system controls how the body's internal organs work; it regulates body temperature, blood pressure, heart rate, and digestion.

Your provider may use this test, and others, to diagnose the following:

• Autonomic neuropathy.
• Complex regional pain syndrome (CRPS).
• Diabetes-related neuropathy.
• Multiple sclerosis.
• Postural orthostatic tachycardia syndrome (POTS).
• Sjögren's syndrome.
• Small fibre neuropathy.

What can I do in preparation for a QSART?

Your provider will meet with you before you undergo a QSART to prepare you for what to expect from the procedure. They will provide specific instructions about what you must do to prepare. These include:

• Avoid taking certain medications that might change the test's findings.
• Avoiding tobacco smoking for at least four hours before testing starts.
• Avoid wearing socks or compression clothing on the day of the test.
• Before the test, change your eating and drinking habits.
• Wear comfortable and loose clothes on the day of the test.
• Avoid putting any lotions or body creams on the day of the test.
• If you have questions about preparing for a QSART, ask your provider before taking your test.

May I eat or drink before a QSART?

It would help if you made minor modifications to your diet and hydration status before a QSART. Your doctor may advise you that:

• Do not consume any food or beverage containing any amount of caffeine eight hours before the test
• Do not consume any alcoholic beverages 12 hours before the test
• Take a light meal three hours before
• Hydrate with many glasses of fluids on the day before the test
• Do not consume any fluids three hours before the test.

What medications can I take before a QSART?

You should keep taking all of your medications unless your doctor directs you to stop taking one or more of them.

Certain medications may impact the results of QSART, including:

• Analgesics.
• Antidepressants.
• Antihistamines.
• Anti-inflammatory agents.
• Aspirin.
• Medications for blood pressure.
• Diuretics.
• Over-the-counter medications for cold or cough (decongestants).
• You should discontinue these medications for at least 48 hours prior to the test.

What happens during a QSART?

Here's what you can expect when you undergo a QSART:

• You will be asked to remove your shoes and socks.
• You will sit or lie on your back on an examination table.
• Your doctor will clean and dry your skin and perform the test on your foot, leg, and wrist.
• Your healthcare provider will place four electrodes (small plastic strips) on your skin. Typically, three are positioned on your leg and one on your wrist. They will also apply acetylcholine to your skin. Acetylcholine is a natural neurotransmitter located inside you. The liquid applied to your skin stimulates your sweat glands during the test.
• When the QSART device is turned on, a tiny electrical impulse is transmitted through the electrodes on your skin.
• Your body will start sweating, and the machine will measure the amount.
• Your provider may move the electrodes to other body parts and repeat the abovementioned steps.

How long does a QSART take?

A QSART is a 45-minute to one-hour process.

Is a QSART painful?

No, A QSART isn't painful, though you'll feel discomfort. The passage of electrical currents can be mildly like a tickling, prickling or burning sensation where the electrodes sit on your skin.

If you do feel some pain, let your provider know.

What to expect after a QSART?

After the test, your provider will remove the electrodes from your skin, and you can put them back on your socks and shoes. You may observe some skin irritation or discolouration following the test, such as redness or a darker skin tone over the areas where your provider placed electrodes. It usually fades away within a few hours.

The information obtained from the test is transmitted to your referring physician. This physician will contact you once the results are available, typically within a few days.

What are the risks of a QSART?

A QSART is not invasive or harmful. You may find some discomfort sensations in the course of taking the test. However, most people can tolerate it without problems. If you can't tolerate the pricking sensation of an electrical current running under your skin, your provider may suggest alternative testing methods.

How do I interpret QSART test results?

Your healthcare provider will interpret the information recorded in a QSART and have the results returned to you within a few days. Test results assess the following:

• How long does it take for your body to begin sweating (onset latency).
• When you reach the peak amount of sweat produced (peak sweat production).
• The total amount of sweat you produce throughout the test (sweat volume).

These results are either standard or abnormal.

QSART normal values

A normal QSART value, or a negative result, indicates that the volume of perspiration you produce and the duration before you begin sweating are normal for your age and sex.

For example, it may take your body approximately one to two minutes to start secreting sweat. The rate of sweat production increases initially in the first five minutes and then starts reducing afterwards.

Normal values vary depending on the type of QSART testing equipment used for the test. Your provider will tell you what a normal result looks like.

What does a positive QSART mean?

A positive QSART means that your test results are abnormal. It means that something is going on that is interfering with the way your autonomic nervous system works.

Your provider may see that your body sweats longer than usual or that your body sweats a lot more during the test, for instance.

A positive QSART result is not a diagnosis but tells your provider that you probably have an underlying medical condition. Your provider can then conducts further tests or seek treatment for your symptoms.

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