Autonomic Testing

Autonomic testing helps find out if your autonomic nervous system (ANS) is working as well as it should. Your ANS controls body functions that happen automatically (without you thinking about them). These functions include your breathing, heartbeat, body temperature, and digestion.

If there are problems with the function of your ANS, it's known as autonomic neuropathy. Autonomic neuropathy damages the nerves that control your internal organs. This can lead to problems with your: Heart rate and blood pressure; Digestive system; Bladder; Sex organs; Sweat glands; Eyes; Blood glucose; The most common causes of autonomic neuropathy include diabetes, autoimmune diseases, some types of medicines, and certain infections, such as HIV.

Autonomic testing can show which part of your ANS is affected and how seriously it's affected. This can help your health care provider develop the most effective treatment strategy for you.

Why this test is done

You may need this test if you have symptoms of autonomic neuropathy, sometimes referred to as dysautonomia. Symptoms will vary depending on which part of your nervous system is affected.

Stomach and gastrointestinal symptoms can include:

• Constipation
• Diarrhea
• Nausea and vomiting

Bladder and urinary symptoms can include:

• Difficulty urinating
• Leaking urine
• Urinating more often than usual

Heart and lung symptoms can include:

• Rapid heart rate
• Shortness of breath with activity or exercise
• Dizziness
• Fainting
• Weakness

Other symptoms can include:

• Too much or not enough sweating
• Sexual problems; such as erectile dysfunction in men and vaginal dryness in women
• The pupils of your eyes being slow to adjust to changes in light and darkness
• Getting low blood glucose and not knowing it (since you may not have the symptoms)

How to prepare

Your provider will give you specific instructions on how to prepare, but many autonomic tests require the following preparations:

• Don't eat or drink anything with caffeine for eight hours before your test.
• Keep well hydrated with noncaffeinated beverages the day before your test.
• Don't drink alcohol for 12 hours before your test.
• Don't smoke or use tobacco products for four hours before your test.

Check with your provider about how to prepare for your test. They will also let you know if you need to stop taking any medicines before your test.

Other names for this test

tilt table test, quantitative sudomotor axon reflex test (QSART), thermoregulatory sweat test (TST), passive head-up tilt test, head-upright tilt test