In diagnosing autonomic neuropathy, a physician is likely to perform a physical examination and compile a medical history of the patient. Autonomic neuropathy may be difficult to diagnose because many of its symptoms are similar to those of other medical conditions.

A physician will start by looking for physical signs that may indicate autonomic neuropathy. This may include abdominal distention or abdominal sounds that indicate decreased movement of food through the digestive tract. An examination of the eyes may indicate sluggishness in pupil reaction. Patients will likely be asked about their symptoms, including their ability to sweat, urinate or have regular bowel movements.

A physician may also conduct autonomic testing, which are a group of tests designed to measure a patient’s heart rate, blood pressure and flow, skin temperature and ability to sweat. Autonomic testing may include:

• Breathing tests. These tests record heart rate and blood pressure in response to breathing exercises. For example, a patient may be asked to take deep breaths for a minute or blow into a tube to increase pressure in the chest (the Valsalva maneuver).
  
  
• Tilt-table test. The patient lies on a table that is tilted to raise the upper part of the body. This stresses the autonomic nervous system (ANS), and the ANS response is measured through blood pressure and heart rate. Lower than normal rates may indicate autonomic neuropathy.
  
  
• Thermoregulatory sweat test. The patient is coated with a special powder and then asked to enter a chamber. As the temperature inside the chamber is increased, the powder on the patient changes color in response to perspiration. Abnormal perspiration activity may indicate autonomic neuropathy.
  
  
• Quantitative sudomotor axon reflex test (QSART). This may be used to measure a patient’s ability to sweat. Electrodes are placed on the patient’s arms and/or legs. Then, a small electrical current is passed through the electrodes to activate the ANS nerves that affect a person’s sweat glands to induce sweating.

An important element in the diagnosis of autonomic neuropathy is ruling out other conditions that may have similar symptoms. Additional tests that may be used in this manner include:

• Barium contrast studies. X-rays of the gastrointestinal tract are taken after a patient has consumed a special liquid (barium). This test may be used to identify physical obstruction or other abnormalities within the digestive tract that may be causing the patient’s gastrointestinal symptoms.
  
  
• Radionuclide imaging. Special radioactive chemicals are introduced into the patient’s body and then imaging tests are conducted in order to identify changes in size, shape, position or function of internal organs. This type of test may be performed to identify abnormal gastric movement, which may indicate autonomic neuropathy or other conditions.
  
  
• Esophagogastroduodenoscopy (EGD). Also called an upper endoscopy, this test is performed by inserting a small, flexible tube with an attached camera through the mouth and into the digestive tract (after a patient has been sedated). This test may identify other causes of a patient’s gastrointestinal symptoms.
  
  
• Ultrasound. Uses high frequency sound waves to produce an image of the bladder and other parts of the urinary tract, which are then analyzed for irregularities.
  
  
• Bladder function tests. These may include a voiding cystourethrogram (VCUG), in which x-rays are taken as the bladder fills and empties. Bladder function tests may indicate whether a patient’s bladder can effectively contract and empty.  

Additional diagnostic tests may be warranted, depending on the suspected cause of a patient’s symptoms.