AUTONOMIC TESTING 101

Many POTS patients e-mail me asking me what tests they should ask their doctor to run when their doctor suspects they have POTS.  I am not a doctor, but I have had many different autonomic tests.  Here are some of the tests commonly performed on patients with a suspected or known POTS diagnosis.  They are not all considered "autonomic" tests, but many of them can be used to evaluate the functioning of the autonomic nervous system.  Some of the tests are used to rule out other diseases, some are to determine how severe the POTS is and some are to help determine the cause of the POTS.  Not every patient needs every test, and not every doctor is aware of the availability or usefulness of each test.  By posting information on these tests here, I am NOT suggesting that every POTS patient needs every one of these tests.

Here is a good instructional video on some of the autonomic tests from the lab of Dr. Peter Novak, a well regarded autonomic neurologist in Massachusetts.



Tilt Table Test
This is probably the most common test giving to people suspected of having POTS.  The tilt test, sometimes called HUT for "heads up tilt," is a non-invasive test.  Sometimes, your doctor may put an IV line in your arm to deliver medication or draw blood during the test, but this is not always done.  Try to avoid an infusion of a stimulant drug just before they tilt you.  Some doctors do this to speed up the test, but it is not very pleasant and not needed to diagnose POTS.  

You start the test laying flat on a table.  They will put a blood pressure cuff on your arm and some electrodes on your test that record your heart rate.  Sometimes they put a 'beat to beat' blood pressure monitor on one or two of your fingers.  Your doctor will strap you to the table, usually with velcro straps.  This is just to protect you from falling in case you faint during the test.  They don't want you falling off the table and getting hurt.  Sometimes they strap you with your arms down at your sides.  Sometimes they strap you with one or both of your arms out in a T shape, like Jesus on the cross.   If they are going to give you medication through and IV line, it is usually given at this time.  Once they have your baseline laying down heart rate and blood pressure (BP) recorded, then they tilt you upright - your feet towards and ground and your head towards the ceiling.  I have heard some people worry about being flipped upside down during a tilt test.  There is no upside down part of a tilt test.  They usually tilt you upright fairly quickly - to mimic the act of going from laying down to standing.  The machines you are hooked up to are going to be recording your heart beat constantly and your BP.  Usually the BP is taken every minute, or constantly if you are hooked up to a beat to beat BP monitor.

They usually tilt you to just about 70-80 degrees - so you are not fully upright.  This is to prevent you from using your leg muscles to stand up, which can interfere with the test results.  It is very important not to wiggle or use your leg muscles at all.  Although it can be a little scary, just try to relax and remember you are strapped to the table so you aren't going to fall.  Tilt tests can last from a few moments (if you pass out right away like I did the first time I had one) to 45 minutes (if you don't pass out at all like I did during my 3rd tilt test).  The point of the test is not to make you pass out.  It is to see how your heart rate and blood pressure respond to the change in position.  Many people do not pass out during the test.

It is important to note that you can have three different results on three different tilt tests - and you could end up with three diagnoses.  This happened to me.  POTS is finnicky and the symptoms may not be consistent from day to day and hour to hour.  Also, any medications or high salt/fluid diet you are on can influence the test restults.  Be sure to talk to your doctor at least two weeks before the test to see if they want you to go off of any of your medications.  If you are trying to confirm or rule out a POTS diagnosis, you do not want to be on any meds that would skew the test results.  Sometimes they want to see how well your POTS meds are working, so they ask you to stay on your meds before the test.  This test is usually performed by an EP Cardiologist.  EP stands for Electrophysiologist.  This is a cardiologist who specializes in the electrical system of the heart.


Supine & Upright Catecholamines
This test can often be performed during a tilt test, although a tilt machine is not needed to complete the test.  This test consists of two blood draws taken about 30 minutes to an hour apart - one in the supine (laying down) position and the other in the upright (standing) position.  The blood is then evaluated for epineprhine, norepinephrine, renin, vasopressin, dopamine, aldosterone and various other hormone and neurotransmitter substances involved in the control of the autonomic nervous system.  Not every lab looks at each of the substances listed.  Some only look at one or two of the substances.  It is important to ask your doctor which substances he/she will be checking for, as you do not want to have to repeat the test at a later date if you can avoid it.  This test is very useful in the evaluation of patients with suspected "Hyperandrenergic" POTS, who commonly have extremely elevated levels of norepinephrine.

It is very important to follow specific procedures for this test, otherwise the results will be skewed.  The catheter to draw the blood out of should be insterted, and then the patient should be allowed to lay down calmly in a quite and dark/dimly lit space for at least a half hour.  The reason the needle is inserted a half hour before the blood draw is because the pain from the needle stick is enough to spike the patients hormone levels, which would alter the test results.  Any agitation, pain, loud noises or distractions could elevate the patients norepinephrine levels, or other substances tested.  The point of the first blood draw it to get blood form the patient in a relaxed state.

After the first "relaxed" blood draw is taken, then the patient should attempt to stand up for about 30 minutes.  Since this is difficult for many POTS patients, the patient should stand for a s long as possible, or sit up and stay busy, sometimes a pattern of sitting and standing can be used since standing for the entire 30 minutes is difficult for many patients.  The patient does not need to be in the calm/quite space at this time.  In fact, putting the patient in a "normal" stress situation is probably helpful, as the point of the second blood draw is too see how much the patients's hormone and neurotransmitter levels change after a half hour of upright activities.


QSART
QSART stands for Quantitative Sudomotor Autonomic Reflex Test.  This is a non-invasive test, although it does involve a mild stinging or zapping sensation on a small area of your skin.  They place electrodes on your lower leg and sometimes your arm as well.  Then a very small and safe electrical current is put on your skin and the electrodes record how much your skin sweats in the area of the electrodes.  A deviation from normal can indicate problems with the autonomic nervous system.  This test is usually performed at an Autonomic Laboratory, which can be hard to find.  Check the research hospitals nearest to your home to see if they have an autonomic lab or at least a good neurology department that may have the equipment needed for this test.  Keep in mind that this test only check one tiny spot on your skin, so if it comes back normal, that does not rule out autonomic neuropathy entirely.  Some people have a patchy distribution of neuropathy, and that may be harder to pick up with this test.


TST
TST stands for Thermoregulatory Sweat Test.  This is like a full body deluxe version of the QSART.  As of early 2012, this test is only offered in three hospitals in the United States - Mayo Clinic in Minnesota, Cleveland Clinic and University Hospital, which also happens to be in Cleveland, down the block from Cleveland Clinic.  For this test, you have to take off your clothes and put on a small disposable bathing suit (bikini for the ladies).  You are then covered with a powder called Azithrin Red.  This is the same powder used to stamp "USDA" on raw beef in the United States.  And yes, after this test your will look like a piece of raw beef.  Once your skin is covered in powder, you lay down in a glass box that is about the size of a large refrigerator, except it is really hot in there.  They take photos of your skin with the powder on, and then the slowly turn up the heat until you begin to sweat.  They take more photos of your skin as time progresses, to view the shape and pattern that you sweat in, and also the amount of sweat you produce.  Your heart rate and body temperature is monitored to make sure you are not overheating.  You can see the test technician the whole time you are in the box.  In fact, at Cleveland Clinic they have photos of tropical beach scenes around the box and they play some relaxing Hawaiian luau music to help keep you calm.  They don't want you to sweat because you are nervous, because that could mess up the test results.  Once the test is done, you get to take a shower and scrub off the powder.  If you cannot shower yourself, they will get a nurse to assist you or let you have a wheelchair to use in the shower.  The powder turns blackish purple after it comes in contact with your sweat, which is why you will look like a side of rare beef when you are done with this test.  Try as you might, you are probably not going to get all of that powder off in the shower, and even if you do, any place that got sweaty gets stained with the dye.  Forehead, armpits, back of your shoulders... mottled black and purple.  I highly recommend wearing black clothes the day of this test and having a long sleeve cover up to wear so when you walk out after the test, people don't like at you like a diseased purple monster.

This test can help reveal patterns of hypohydrosis (lack of sweating), hyperhydrosis (too much sweating), delayed sweat responses, unusual sweat patterns (for example, no sweat on upper body and normal sweat on lower body) and certain neurological conditions.  The doctors can sometimes even identify where a spinal cord or brain lesion is, based on the sweat pattern.


Valsalva Maneuver
This is a fairly simple non-invasive test.  Your doctor will give you a tube to blow into.  Sometimes the tube has a pressure gauge on it and you are instructed to keep the pressure above a certain number.  Your doctor will be monitoring your heart beat and blood pressure before, during and after you blow into the tube.  Your doctor may make you breathe in and out very fast a few times or hold your breath during this test.  The results are used to help evaluate your autonomic reflexes.


Small Fiber Nerve Skin Biopsy
There are two different types of skin biopsies that can be done on to evaluate the patient's small fiber nerves.  One looks at the small fiber sensory nerves, and the other looks at small fiber autonomic nerves.  These are both very minor 3-4mm skin biopsies that just feel like a pinch.  The generally don't require stitches or leave any numbness.  A good pathologist can count the number of nerve fibers present, and note whether there are any damaged fibers or other unusual features in the biopsy tissue.  About 50% of POTS patients are known to have autonomic neuropathy.  Many doctors are aware of the skin biopsy that looks for small fiber sensory nerves, but there seems to be less awareness of the availability of small fiber autonomic nerve analysis.  Here is a five minute educational video for doctors on how to perform the skin biopies from a company that produces the test kits.  The actual biopsy is performed just after minute 2:30.  As you can see, it is very small.


Nerve Biopsy
This is very different than a small fiber nerve skin biopsy.  During a nerve biopsy, a doctor cuts out a portion of a patients large fiber nerve and exams it for any abnormalities.  The nerve is often taken from the foot of shin area, and this procedure can leave a sizable area of numbness or even muscular weakness after the procedure.  A nerve biopsy is usually only considered once a Nerve Conduction Study(NCS) or Eletromyelogram (EMG) has shown an abnormalities in large fiber nerves.  Large fiber nerve involvement is uncommon in POTS, although some patients may have an underlying neurological condition that is causing their POTS, and sometimes that underlying condition can involve large fiber nerves.


Muscle Biopsy
I include this here simply because so many patients confuse the various forms of biopsies.  A muscle biopsy is not a routine POTS test.  However, it is sometimes used to evaluate patients for mitochondrial diseases, neuromuscular disorders and to determine the cause of weakness.  Muscle biopsies can show abnormalities in the nerves that innervate muscles (motor nerves) or abnormalities in the muscle tissues. This is an important distinction.  The test should not be done on a muscle that was subjected to EMG testing within the past month, as that can impacts the results.


Upper Endoscopy
While not truly an autonomic function test, dysautonomia patients who have severe or disabling GI symptoms may be advised to have an upper endoscopy.  Prior to the test, the patient usually has to fast for a certain period of time - less than a day usually.  This is important because if there is food in your stomach your doctor won't be able to see things clearly down there, and it is also dangerous to eat or drink prior to being sedated, because it increases your risk of vomiting and choking on vomit. If you are told not to eat or drink before this test, follow those instructions carefully. During this test, the patient is given a sedative to make them drowsy, and the doctor places a long thing tube in the mouth, down the throat, through the esophagus and into the stomach.  The tube has a small camera and a light on the end of it, so the doctor can look for ulcers, inflammation and other abnormalities in the stomach.  Sometimes the doctor will take a small biopsy of the stomach using the endoscopy tube, to make sure the stomach lining is normal when viewed under a microscope.

After the test, sometimes you can have a mild sore throat from the tube they slid down into your stomach.  Just drink plenty of fluids and maybe eat soft foods for a day or two, like mashed potatoes or soup.



Colonoscopy
This is essentially the same thing as the upper endoscopy described above, except the doctor takes a slightly different tube and places it into the anus and up into the colon and intestines.  This is sometimes done to rule out various causes of GI distress and to obtain biopsies for things like Celiac Disease (although most doctors prefer a small intestine biopsy to diagnose Celiac, which is usually obtained during an endoscopy).

You are sedated during this procedure and it does not hurt.  Before this test, most patients are given something the night before to drink to help clean out their intestines.  The most common cleanser given is called GoLytely.  It is clear and viscous and sometimes they have flavor packets you can add to it to make it more tolerable.  Either way, it's not fun to drink.  I couldn't have the flavor packets because they had something in them I was allergic to, so I had to drink mine straight up.  I found it easiest to cover a glass with saran wrap and stick a straw through it (so I wouldn't have to smell the liquid).  It tasted so gross that I was vomiting it back up, so my doctor let me suck on a watermelon Jolly Rancher candy as I drank it.  I have also heard of some people drinking it with clear apple juice.  I would ask your doctor first.  And once you start drinking the cleanser, you do not want to be far from the bathroom.  Find your comfy PJs and be prepared to hang out in the bathroom for the rest of the night.  

Gastric Emptying Study (Gastric Emptying Scintigraphy)

Many patients with POTS and other forms of dysautonomia have impairments to the movement of food through their GI tract.  This is called gastroparesis.  This test helps your doctor determine whether you have a delayed movement in your GI tract.  During a Gastric Emptying Study, you eat something solid (like a scrambled egg), and something liquid (like water or broth), that has been laced with an radioactive substance, called a radiotracer.  Then the doctor or radiology technician places a machine similar to a Geiger counter over your stomach to detect the amount of radiotracer left in the stomach.  The levels are usually measured at 1, 2, 3 and 4 hours.  If 10% of the food is still left in the stomach at the four hour mark, the patient is usually diagnosed with gastroparesis.  This test can also be used to detect food moving too quickly through the GI tract.

Barium Swallow and Modified Barium Swallow

During a regular Barium Swallow, you are told to fast for a period of time before the test.  Then you are given something to eat that has some barium on it.  Barium shows up on x-rays very well, so this test can be used to see if food is moving properly though your GI tract.  During the regular barium swallow, they x-ray your stomach area.  

During a modified barium swallow, they use a moving x-ray image called video-flouroscopy to watch you chew and swallow gooey/chewy foods, crunchy/dry foods, liquids and sometimes sugar pills that have barium on them.  They are looking to see if your tongue, throat, esophagus and lower esophageal sphincter (valve at the top of your stomach) are functioning properly.

Breath Test

Some doctors use a breathe test to determine how well the stomach is functioning.  The patient eats a meal containing a small amount of a radioactive isotope.  Then breath samples are taken to determine how much of that isotope is present in the carbon dioxide the patient exhales.

Esophageal Motility Study (Esophageal Manometry)
During this test, a doctor places a thing tube into the nose, through the back of the the throat
and into the esophagus, then down into the stomach.  Once the tube is in place, you are asked to swallow.  The tube measures the pressure inside your esophagus.  This can be used to check if your esophagus is working properly to move food and liquids down to your stomach.


Blood Tests
In addition to the supine & upright catecholamine tests described above, here is a sampling of some of the more common blood tests doctors perform on patients suspected of having POTS.  Most often, these tests are used to rule out other illness as the underlying cause of the patients POTS symptoms.  Sometimes, the tests are used to help identify which treatment options would be most beneficial for a POTS patient.

CBC  - complete blood count - this looks at a patinets red blood cells, white blood cells, hematocrit, etc.  This would help a doctor look for signs of infection, anemia or other hematological abnormalities.

BMP or CMP - basic or complete metabolic panel - this looks at electrolytes, which are often off balance in POTS patients, particularly potassium, which is often low.

Mono/Epstein Bar Virus - about 50% of POTS patients develop POTS after a viral infection, and since Eppstein Bar is one of the most common human viruses, and is also known to cause symptoms similar to POTS, this virus is commonly tested for.  Keep in mind that almost 95% of humans have been exposed to Epstein Bar by the time they reach adulthood, and once you have had it, your body will continue to produce IgG antibodies to it probably for the rest of your life.  A positive IgG does not mean you have an active Epstein Bar infection.  There are four or five different tests for the Epstein Bar virus that are required to decipher between a current infection, a recent infection, or a long ago infection.  You should probably see an experienced infectious disease specialist if you or your doctor suspect Epstein Bar or mononucleosis.

Lyme Disease and associated co-infections like Bartonella, Erlichia and Babesosis - when ticks transmit enough saliva to transmit a disease, they rarely only transmit one infectious agent.  Most ticks have numerous pathogens in their bodies, and as such, it would be rare to find a patient who has become sick from a tick bourne illness who has only one type of infection.  Lyme and it's common co-infectious can be notoriously hard to test for and diagnose.  The standard blood tests for Lyme, both the Western Blot and the ELISA, are notorious for high false negatives - that is, they will return a negative result, when the patient actually has a known case of Lyme Disease.  If you suspect Lyme or one of it's co-infections, I highly recommend finding a reputable LLMD (lyme literate medical doctor).  LLMD is not some official designation, so any doctor can claim to be an LLMD.  Probably the best way to find a good Lyme doctor is to call your local or state Lyme Disease patient alliance.  They will know who is good at diagnosing and treating Lyme, and who isn't.

Mycoplasma - there are several species of mycoplasma bacteria that cause infections in humans, the most common of which is Mycoplasma pneumoniae - the bacteria that causes "walking pneumonia."  While most cases of walking pneumonia are experienced as an annoying chest cold, but not as severe as a case of true "pneumonia," a small percentage of Mycoplasma pneumonia cases can lead to neurological impairment.  Mycoplasma pneumonia has been implicated in the onset of POTS, and it is treatable with strong antibiotics if needed and if it is caught early enough in the infection.

B12, Homocysteine, Methylmalonic Acid - these tests are used to make sure your B12 levels are normal, and to make sure your body is able to properly utilize B12.  B12 is important for proper nerve health, and if your B12 is low, it could be the cause of you POTS symptoms.

CoQ10 - This is an essential vitamin-like substance that is found in all cells in the human body.  It is required for energy production within the cell and plays and important role as an antioxidant.  Normal levels of CoQ10 are important to overall health.

Vitamin D (D2 and D3) - this is low in most Americans and Europeans (those residing in far northern latitudes), and is linked with an increased risk for infection, autoimmune diseases and even some forms of cancer.  While low Vitamin D is probably not the cause of your POTS, correcting any deficiency you may have could help you feel better overall.

Lead, Mercury, Cadmium, Arsensic (organic and inorganic) - these are commonly tested to rule our heavy metal poisoning.  Even if you have no known exposures to these substances, it is actually quite common to have elevated levels of these substances if you live in an industrialized nation.  My cadmium was high, although my doctor told me this was just the same as everyone else who lives in New York.  Cadmium is in air pollution and it rains down into our drinking water and lakes and streams, and that is how it ends up in our bodies.

Immune System Related Tests
Sed Rate and CRP - these are tests that look for general inflammation in the body.  If they come back positive, it does not tell the doctor what specifi disease or inflammatory process is occuring, but it does give a general clue that there is some inflammatory process occuring - wheter it be from an injury, inflammation, infection, allergies, autoimmune disease, etc.

SS-A and SS-B - These are antibodies seen in about 70% of Sjogren's Syndrome patients.  Sjogren's can be the underlying cause of POTS.  However, even if your antibodies are negative, that does not rule out Sjogren's.  Only a minor salivary gland lip biopsy can rule it out for sure.

RF - rheumatoid factor.  Rf is seen in several autoimmune diseases, some of which can cause autonomic neuropathy and in turn POTS.

ANA and ENA - this are also antibody tests which can be positive from various conditions, some of which are autoimmune.  ANA can also be elevated after infections.

Lupus Band Test - this is a minor skin biopsy used to evaluate a patient for Lupus, and autoimmune disesae that is known to be associated with some cases of POTS.

Complement Levels - your doctor can test various complement levels, like C3, C4 and C5, to see if your immune system is under an abnormal influence, possible from an autoimmune disease.  And elevated or reduced complement level does not confirm a specific autoimmune disease, but if gives your doctor a hint that something is going on with your immune system.

Paraneoplastic Panel - this is a panel of several antibody tests to look for neurological antibodies associated with rare cancers.  These cancers are hard to detect on scans, but often the antibodies they trigger cause neurological damage before the tumors can be seen.  In the US, this test is usually performed at your home lab and then sent off to Mayo Clinic's lab in Minnesota.



This is only a partial list. There are many other tests your doctors may perform to evaluate you for POTS and to try to identify the underlying cause of your POTS.