Sweat Test Question

[nunntrio]

I just had a QSART done on my legs that came back normal. I want to rule out completely that I do not have nerve damage that is causing my POTS. Is there any value to having a thermoregulatory sweat test or is the QSART a full proof test. I have a lot of numbness (showed up on EEMG) and I want to make sure that is not causing POTS. The Dr, that ran the test said I do not have a automonic nerve problem but he spent a whopping 6 minutes talking to me.

Any input would be great,

Thnks

[arizona girl]

I believe both those tests look for small fiber neuropathy. There is actually a better test that can do that now and will show for sure if you do or do not have small fiber. It is a skin biopsy. In arizona if you go to the Phoenix Neurological associates web site they talk about it there. You can google skin biopsy for small fiber and see if there is a location closer to you that does them or call phoenix neuro and ask them where to get it done. My Doc. there Dr. Levine did the biopsy on me they also do the labs on the specimen as well. My results showed that nerve fiber density was below normal. I also have symptoms of autonomic neuropathy. The small fiber nerves are found in your peripheral and in all parts of the body that control your autonomic functions.

An emg usually shows whether the large fiber nerves are effected. Large fiber nerves usually effect your motor function. Knowing what your symptoms are will point you in the right direction. You can have only large or only small or you can have both, that with type of symptoms will provide the correct diagnosis. Google large fiber nerve damage and see what neurological conditions for that pop up and see if one of those fit your symptoms. Your doc may be right saying that because the Qsart was normal you don't have autonomic, because he was looking for small fiber damage. I also don't think Qsart can 100% exclude small fiber. The skin biopsy is now the gold standard.

Were you diagnosed with pots because you had a positive tilt table test? Neuropathy is not the only condition that can cause the pots symptoms. If you look on the main dinet page under Pots Place you can read about the many different causes under the sections causes and mechanisms. That is what helped me know enough to ask for the small fiber testing and the skin biopsy. Hope this helps!

I just had a QSART done on my legs that came back normal. I want to rule out completely that I do not have nerve damage that is causing my POTS. Is there any value to having a thermoregulatory sweat test or is the QSART a full proof test. I have a lot of numbness (showed up on EEMG) and I want to make sure that is not causing POTS. The Dr, that ran the test said I do not have a automonic nerve problem but he spent a whopping 6 minutes talking to me.

Any input would be great,

Thnks

[Tachy Phlegming]

You need a TST for certain reasons. The TST combined with the QSART can give you evidence of where sudomotor problems may originate.

Google Harrison's neurology in clinical Medicine, p. 335

(I can't figure out how to put that link in so maybe someone else can).

[erikainorlando]

But then if you have an abnormal sweat test does this mean that there is damage to the the small fibers....autonomic fibers?

[nunntrio]

Thanks for the reply. I was told I have POTS based on a positive TT test and a posture study (done at Vanderbilt). I want to find the cause of my POTS. I decided to start with nerve issues because I do have a lot on numbness in my feet and legs. I went to a nerve Dr. closer to where I live (Houston). He did a QSART and an EMG and said my auto. nerves were fine. However he began to question the POTS diagnosis since my blood pressure fell with both my TT test and posture study. I feel like he dismissed me because he did not agree with the diagnosis so I am not confident that his assesment of no autonomic nerve damage is accurate. I actually left his office very confused. Anyway, I spent 2 weeks at Vandy and felt that they would not have kept me if the questioned the POTS diagnosis. I do have a >30 BPM increase upon standing. I will look into a nerve biopsy. If that comes back normal I know I can rule our nerve damage as the cause and look into other issues.

Thanks for the reply.

[nunntrio]

You need a TST for certain reasons. The TST combined with the QSART can give you evidence of where sudomotor problems may originate.

Google Harrison's neurology in clinical Medicine, p. 335

(I can't figure out how to put that link in so maybe someone else can).

THanks I will look into that as well.

[arizona girl]

Thanks for the reply. I was told I have POTS based on a positive TT test and a posture study (done at Vanderbilt). I want to find the cause of my POTS. I decided to start with nerve issues because I do have a lot on numbness in my feet and legs. I went to a nerve Dr. closer to where I live (Houston). He did a QSART and an EMG and said my auto. nerves were fine. However he began to question the POTS diagnosis since my blood pressure fell with both my TT test and posture study. I feel like he dismissed me because he did not agree with the diagnosis so I am not confident that his assesment of no autonomic nerve damage is accurate. I actually left his office very confused. Anyway, I spent 2 weeks at Vandy and felt that they would not have kept me if the questioned the POTS diagnosis. I do have a >30 BPM increase upon standing. I will look into a nerve biopsy. If that comes back normal I know I can rule our nerve damage as the cause and look into other issues.

Thanks for the reply.

Actually it is a skin biopsy not a nerve one. It is also way less painful and with less left over side effects then a nerve biopsy. Also at Vandy, I went there too, weren't you mainly being tested at their cardiovascular center? Did you see neurologists when you were there? From what I understand there are only a handful of places doing the skin biopsy in the US. I do agree though if vandy put you thru all those tests and they said you have pots, I would believe them. On my tilt test my bp/hr went up up up, until after the nitro I had a sudden drop and passed out. So I don't agree with the tx's doc, if he is dismissing you if it went down. You can have any variation of abnormal bp/hr response. My diagnosis was pots with syncope. After my biopsy I know that it is a neurological condition exhibiting cardiovascular symptoms. The good news is my neurologist ordered plasmapheresis as he believes I have the neuropathy due to an autoimmune condition. I have had 8 treatments so far and amazingly my symptoms are improving. The great thing about this treatment is we are going at the cause and not just treating symptoms. I haven't taken my bp meds in over a week. Hope you get your answers soon. If your in texas your not too far to come see Dr. Levine. He also test for all those scary causes listed here on dinet to rule them out.

[Christy_D]

My son had the TST test done in January. With that test they also diagnosed him with small fiber neuropathy. He did not sweat on the entire midsection of his body or on his upper left arm. This helped explain why he hates any heat on his stomach, abdomin area(doesn't even like the heat from sunlight through a car window).

[erik]

Google Harrison's neurology in clinical Medicine, p. 335

(I can't figure out how to put that link in so maybe someone else can).

I haven't found that exact reference, but here is an example of how to link to a Google Book (if that is what you mean). One can't just bring up a given page on demand so one should pick a phrase on the target page and then search for that phrase... then once there sometimes there is a "LINK" button in the upper right that generates something like this:

http://books.google.com/books?id=3kw0gwdYX...ART&f=false

It's tricky because they can't just put the whole book up "on demand" but sneak bits of it out as a teaser. This trick kind of gets around that for specific stuff. I searched for "QTST QSART" and found a similar sort of thing. Maybe can do this trick for something on Page 335 of Harrison's??? Not sure, sometimes these things don't work!

[nunntrio]

Arizonagirl,

Thanks for the reply. Somehow I missed it when you first posted it. Did you use Dr. Levine to help you get to the bottom of what is going on with you? I would go just about anywhere if there is a Dr. that is will to really look into what is causing my POTS. When I went to Vanderbilt they just tested me for the current research protocols they were working on and I did not ever see a Neuro. Yes, I think they were all Cardio. Dr.'s. However they did recommend on my discharge papers that I have and EMG because of the degree of neuropathy. Thank you for sharing your story. It is very encouraging to me. The fact that you were able to track down the cause of the POTS and treat that and not just mask the symptoms. Do you think Dr. Levine would be the best place to go if I wanted to try and find what is causing my POTS (or at least rule out the known causes)? Also, Do you know anything about other Dr.'s/Hosipitals that might do this?

Thanks,

[Guest tearose]

The thermoregulatory sweat test is one way of helping with a diagnosis. It is a horrible test to have too.

Like many tests, if you are more "symptomatic" at the time of the test, I believe it will show the real dysfunction clearer.

[ramakentesh]

i think depending on who your speaking to that about 4 out of 20 POTS patients have small fiber or long tract neuropathy that causes High flow pots in the hands and feet that is rarely visible. usually the hyperadrenergic state results in normal vasoconstriction but with excessive central adrenergic stimulation because cardiac nervation is usually intact. The body has to use excessive norepinephrine to get the hands and feet / legs to constrict appropriately but the heart and central vasculature is not impaired so is highly sensitive to this norepinephrine increase - its almost a norepinephrine resistance scenario exclusive to the hands and feet.

Other POTs patients (the other 60% or so) have either low flow POTs - reduced arm and leg blood flow and excessive vasoconstriction or the Hyper state and or normal flow POTS ( a larger subgroup) with stomach pooling and parasympathetic withdrawal and impaired cerebral autoregulation.

this gets confused because around 40% of patients have inappropriate renin activity and this tends to cross over with all groups.

The low flow subgroup is broken up into the hyper Angiotensin II reduced neuronal nitric oxide group with vasomotor failure and the NET deficiency with increased all over vasoconstriction, postural hypertension and cerebral vasospasm as the means by which cerebral blood flow is reduced.

[nunntrio]

i think depending on who your speaking to that about 4 out of 20 POTS patients have small fiber or long tract neuropathy that causes High flow pots in the hands and feet that is rarely visible. usually the hyperadrenergic state results in normal vasoconstriction but with excessive central adrenergic stimulation because cardiac nervation is usually intact. The body has to use excessive norepinephrine to get the hands and feet / legs to constrict appropriately but the heart and central vasculature is not impaired so is highly sensitive to this norepinephrine increase - its almost a norepinephrine resistance scenario exclusive to the hands and feet.

Other POTs patients (the other 60% or so) have either low flow POTs - reduced arm and leg blood flow and excessive vasoconstriction or the Hyper state and or normal flow POTS ( a larger subgroup) with stomach pooling and parasympathetic withdrawal and impaired cerebral autoregulation.

this gets confused because around 40% of patients have inappropriate renin activity and this tends to cross over with all groups.

The low flow subgroup is broken up into the hyper Angiotensin II reduced neuronal nitric oxide group with vasomotor failure and the NET deficiency with increased all over vasoconstriction, postural hypertension and cerebral vasospasm as the means by which cerebral blood flow is reduced.

Thanks for the response. You seem to have a ton of knowledge so I hope you don't mind if I ask a few questions. I've read through the tpes you listed and have a basic understanding of them. How do you know which one of these groups you fall into? Or where can you go to find out?

[arizona girl]

Hi, I must of missed this, sorry for late reply. What I would say is that emg doesn't rule out neuropathy, only large fiber neuropathy. I know that are several small fiber biopsy places in the nation. My pheresis is done outpatient at Good Samaritan in phoenix. The treatment is twice a week, so you need to be near a hospital or center that does this outpatient. I don't know where the other hospitals are. There may be one nearer you. I would call Dr. Levine's and find out if there is someone closer to where you live. Phoenix Neurological does have a web page and is getting ready to open their own autonomic lab minus tilt. A neurologist that specializes in autoimmune neuropathy is the type you are looking for. My experience at vanderbilt was similar they have a research agenda that they stick pretty close to.

I feel very lucky that l found Levine. If I hadn't asked about small fiber I would never have known he existed. The TTT and skin biopsy totally changed the course of my treatment and testing. I'm hopeful I will improve, but research, testing and treatment for small fiber is very young. The autoimmune factor is also less researched in dysautonomia's. I have had mono and been exposed to TB, HHV6 and cytomegalo viruses. Dinet and a doctor at UCLA who told me not to accept that diagnosis, made me realize that I couldn't settle for just a pot's diagnosis and that it was probably being caused by something else. We know here there a lots of other causes. I don't understand why anyone once pots is diagnosed wouldn't pursue it further.

I'm so glad that my story was encouraging to you. That is why I posted it, if I can help anyone else get to a medical conclusion faster then I did, then my ardeous course to diagnosis won't have been for nothing. Good luck with this and don't give up until you are satisfied. The fact that Vanderbilt says you should see a neuro, really supports your cause and gives you credibility.

Arizonagirl,

Thanks for the reply. Somehow I missed it when you first posted it. Did you use Dr. Levine to help you get to the bottom of what is going on with you? I would go just about anywhere if there is a Dr. that is will to really look into what is causing my POTS. When I went to Vanderbilt they just tested me for the current research protocols they were working on and I did not ever see a Neuro. Yes, I think they were all Cardio. Dr.'s. However they did recommend on my discharge papers that I have and EMG because of the degree of neuropathy. Thank you for sharing your story. It is very encouraging to me. The fact that you were able to track down the cause of the POTS and treat that and not just mask the symptoms. Do you think Dr. Levine would be the best place to go if I wanted to try and find what is causing my POTS (or at least rule out the known causes)? Also, Do you know anything about other Dr.'s/Hosipitals that might do this?

Thanks,

[Guest tearose]

in response to this from arizona girl... "I don't understand why anyone once pots is diagnosed wouldn't pursue it further."

I'm just thinking outloud here...

First, if the treatment plan you have is working then the dx of POTS got you to a better place. That may be enough for some.

Further,

After hundreds of tests and many trips to specialists we all somehow have learned to manage the best possible with the dx of POTS. Some people have EDS or other things that contribute to their POTS/Dysautonomia and other unique body challenges. There are so very many other possibilities you can make yourself get sick trying to find the "one final answer" in a field that is still so new and unknown... there is MCAD, Mitochondrial Diseases, auto-immune possibilities...at what point is it good to step back and try the "fix" without enduring the thousands of dollars and many more tests which may still give no definitive answer?

I recently tried using CoQ10 at high doses and only got to 800mg and had to stop because I got migraines taking it! It spared me doing the MITO workup because the "treatment" made me sicker that I am right now.

I guess it is a very personal thing we discuss with our PCP's.

tearose

[arizona girl]

Of course that is what I meant there are many things that can cause it and some of them are life threatening. I'm speaking to people who are new to Pots, or who haven't had a "fix" or affective treatments yet and aren't satisfied. Some newbie's may not even know that anything else could cause pots. There has already been a thread about this on the forum. One of the things Dr. Grubb said to me was "I worry about my patients who attribute everything to their Pots diagnosis, because sometimes they miss what is really wrong with them like cancer, and they find out to late. You can have more then one thing wrong." Small fiber is only one of many that could be considered. Believe me once I knew what to test for from dinet, I tested for everything I could, thanks also to a neuro who, also knew what to test for without me asking. The skin biopsy was so easy and simple. The TTT test, skin biopsy and now catehcolamine test have been the first truly nonsubjective positive diagnostic findings I've had. Those of us who have had positive TTT's after being told for so long that nothing was wrong, fell such a sense of relief and so vindicate that we think finally this it, they've figured it out. Well it sort of is, in truth though it is another opportunity for new doors to open that couldn't be opened before. II want to get better if I can, treating symptoms only hadn't worked for me, it makes sense to try to find cause and treat that if possible. Just because there are so many things to wade through doesn't mean we shouldn't at least attempt too. Of course I agree it is personal decision, but if possible it should be an informed one.

This is what Dr Yan Go at UCLA said to me, "Your BP went up on TTT? Don't let them tell you it's Pots, you have not had a complete work up yet, there are many things this could be including small cell cancer, go to mayo." She scared me. If she hadn't said anything and I had not read the research here on dinet, I too might have just stopped with pots. I spent two years in the process trying the traditional treatments for pots, as I'm ortho hypertensive they really did little and I had terrible side affects from the beta blocker vanderbilt put me on. If you already know your pots is secondary to something else like EDS or Anemia treating that will hopefully improve symptoms, I do know that. I wouldn't tell anyone how to test or treat other known conditions, unless I had them myself. I can only speak to my story and hope to help shorten the course to diagnosis for someone else who is new to pots and may have similar symptom patterns.

Thanks to dinet I was able to read through all the different causes and recognized myself/symptoms as small fiber, it turned out to be the right one this time. Though it is probably autoimmune based, mine is idiopathic and can't be proved other than by symptom improvement from treatment. Like pots many things can also cause small fiber neuropathy. Dr. Grubb told me they are finding new antibodies all the time.

I've been sick for a very long time, same symptoms, different diagnosis, tried treatments for all, to no avail no improvement, except for glucophage for the PCOS/insulin resistance. Yes, I too have at times given up and had enough or didn't have insurance. Then things would get worse and I'd have to get back on the horse again. The truth is when I first got sick they probably couldn't even diagnosis small fiber or treat it, but they can now. How much better I will get remains to be seen, but if I do I will surely let you all know. Then you can decide for yourselves if it fits you and if you should consider pursuing it. Surprising to me there have been changes, I was skeptical, I didn't even want to get my hopes up. It is still too soon to know, but it is a step in the right direction.

I wish there were other here who had been down the path I'm now going on. I would love to ask them questions and get guidance. So far though no else here, has responded that they have done what I'm doing. Please if there is anyone else, I'd love to hear from you? If there is no one else, then I hope my story and treatments one day can help someone else. I love how all our different stories come together here on the forum and create a better more full understanding of dysautonomia.

[nunntrio]

Hi, I must of missed this, sorry for late reply. What I would say is that emg doesn't rule out neuropathy, only large fiber neuropathy. I know that are several small fiber biopsy places in the nation. My pheresis is done outpatient at Good Samaritan in phoenix. The treatment is twice a week, so you need to be near a hospital or center that does this outpatient. I don't know where the other hospitals are. There may be one nearer you. I would call Dr. Levine's and find out if there is someone closer to where you live. Phoenix Neurological does have a web page and is getting ready to open their own autonomic lab minus tilt. A neurologist that specializes in autoimmune neuropathy is the type you are looking for. My experience at vanderbilt was similar they have a research agenda that they stick pretty close to.

I feel very lucky that l found Levine. If I hadn't asked about small fiber I would never have known he existed. The TTT and skin biopsy totally changed the course of my treatment and testing. I'm hopeful I will improve, but research, testing and treatment for small fiber is very young. The autoimmune factor is also less researched in dysautonomia's. I have had mono and been exposed to TB, HHV6 and cytomegalo viruses. Dinet and a doctor at UCLA who told me not to accept that diagnosis, made me realize that I couldn't settle for just a pot's diagnosis and that it was probably being caused by something else. We know here there a lots of other causes. I don't understand why anyone once pots is diagnosed wouldn't pursue it further.

I'm so glad that my story was encouraging to you. That is why I posted it, if I can help anyone else get to a medical conclusion faster then I did, then my ardeous course to diagnosis won't have been for nothing. Good luck with this and don't give up until you are satisfied. The fact that Vanderbilt says you should see a neuro, really supports your cause and gives you credibility.

Arizonagirl,

Thanks for the reply. Somehow I missed it when you first posted it. Did you use Dr. Levine to help you get to the bottom of what is going on with you? I would go just about anywhere if there is a Dr. that is will to really look into what is causing my POTS. When I went to Vanderbilt they just tested me for the current research protocols they were working on and I did not ever see a Neuro. Yes, I think they were all Cardio. Dr.'s. However they did recommend on my discharge papers that I have and EMG because of the degree of neuropathy. Thank you for sharing your story. It is very encouraging to me. The fact that you were able to track down the cause of the POTS and treat that and not just mask the symptoms. Do you think Dr. Levine would be the best place to go if I wanted to try and find what is causing my POTS (or at least rule out the known causes)? Also, Do you know anything about other Dr.'s/Hosipitals that might do this?

Thanks,

I actually email my local neuro and asked of he would be willing to do a skin bioopsy. He said he would but of course I could not get an appointment for another month. I will have to confirm with him that it is a small fiber. If not hopefully he can help me find where I can get one done close by. I live in Houston which has a huge medical center so I would hope I could get one. I also hope he is open to helping me this time. Last time he blew me off but he has since received the report from Vandy confirming the POTS. You are right if nothing else my trip to Vandervbilt has given be credibility for my health problems.

Like you I have a hard time excepting POTS as my final diagnosis. I understand that is a very personal decision and everyone must decide when enough is enough when it come to tests. For myself, I have not been helped by any treatments (Beta Blokers, Florinef, Midrodine etc) In fact they all make me feel 1000% worse. Because of this, the only hope I have right now of ever feeling better or having much quality to my life is finding the underlying cause and treating it. I have decided to rule out the causes one by one. At this point I am focusing on the nerves because it seems like a logical place to start considering my neuropathy. I do differ from you in that my Blood Pressure does drop slightly on the TTT and Posture Studies. I think if it rose it would be a greater indicator of a nerve problem.

I would love to find a Dr. that is willing to help me with my journey. It is overwhelming to try go a seperate Dr. rule out each cause individually. I need to do someresearch, I may end up at Dr. Levine. However I would like to try someone closer if possible. There are some people on this forum who sound like they have Dr.'s that are willing to do that. At this point my Dr.'s just want to throw different drugs at me (not of which have helped) and not search for the cause.

Please keep us posted on your treatment. I will be very interested to hear if it helps. The boundries of medicine have to be pushed if progress is to be made.

[Elegiamore]

I feel that I should share this: the absolutely WORST POTS experience of all time for me was thermoregulatory sweat test, which had at Mayo, MN. They cover you with powder and put in you a box, like a coffin, with loud music to distract you. Then they turned up the heat big time. They had told me that it would be only so many minutes, but soon I realized that it was past the time and I was STILL IN THE BOX and about to syncope.

I started beating and begging for help when I noticed that something massive was going on in the room. Eventually, they came and told me they were "sorry" but that they had an emergency and LEFT ME IN TOO LONG! I could not breath and was unable to comprehend how it was supposed to be so blasted hot in that box.

There are no words for how sick I was, but since I was lying down, I didn't syncope.

When they open the box, they check out the powder to see where you did or didn't sweat and wash you off. By that time, they said "we are walking you out but do NOT look across the room to the other box." Duh, I looked.

They hadKILLED THE LADY in the other box from the malfunction of both hot boxes. My husband, sitting in the lobby, went up to the desk and asked where am I in that it was taking way too long. Then he sees them wheel a body bag out of my room. He went totally hysterical as they made him wait to tell him which patient died in the BOX!

This is a TRUE STORY. I asked where was my IV for sweating up a storm and being put in a defective box, and they REFUSED to give me on. As my husband wheeled me to the room, of course, I passed out cold. THEN I had terrible suffering (throwing up, all over severe pain, severe chest pain, etc.) until we waited for them to give me an IV.

If you gave me a million dollars, I would not allow Mayo to test me for anything ever again.

And natch, I had POTS and a negative result from the box test. Hope that helps.

[Christy_D]

I feel that I should share this: the absolutely WORST POTS experience of all time for me was thermoregulatory sweat test, which had at Mayo, MN. They cover you with powder and put in you a box, like a coffin, with loud music to distract you. Then they turned up the heat big time. They had told me that it would be only so many minutes, but soon I realized that it was past the time and I was STILL IN THE BOX and about to syncope.

I started beating and begging for help when I noticed that something massive was going on in the room. Eventually, they came and told me they were "sorry" but that they had an emergency and LEFT ME IN TOO LONG! I could not breath and was unable to comprehend how it was supposed to be so blasted hot in that box.

There are no words for how sick I was, but since I was lying down, I didn't syncope.

When they open the box, they check out the powder to see where you did or didn't sweat and wash you off. By that time, they said "we are walking you out but do NOT look across the room to the other box." Duh, I looked.

They hadKILLED THE LADY in the other box from the malfunction of both hot boxes. My husband, sitting in the lobby, went up to the desk and asked where am I in that it was taking way too long. Then he sees them wheel a body bag out of my room. He went totally hysterical as they made him wait to tell him which patient died in the BOX!

This is a TRUE STORY. I asked where was my IV for sweating up a storm and being put in a defective box, and they REFUSED to give me on. As my husband wheeled me to the room, of course, I passed out cold. THEN I had terrible suffering (throwing up, all over severe pain, severe chest pain, etc.) until we waited for them to give me an IV.

If you gave me a million dollars, I would not allow Mayo to test me for anything ever again.

And natch, I had POTS and a negative result from the box test. Hope that helps.

I am so sorry you had that experience! That sounds absolutely horrible. My sons TST was done at University Hospital in Cleveland and was not bad at all. The tec talked to him the whole time and my husband and I were able to stay in the room with him where he could see us. They kept asking him how he was if he could stay in for a couple of minutes more. They gradually brought the temperature up and gradually cooled him down. It was very controlled.

[spaceorca]

Here are a few thoughts on this very interesting thread:

First, as many probably know (but for the benefit of some newbies), there are two types of "sweat" tests. One is the thermoregulatory sweat test where they powder you up, put you in a box, and heat you up. My son has refused to have this test done (and, in fact, none of his doctors have pushed it) for exactly the reason suggested by the Mayo experience: It is so clear that he doesn't sweat, and that he quickly overheats, that it would be very dangerous for him to do this test. Hyperthermia is very dangerous!! I personally think it is irresponsible for any doctor to suggest the TST for a patient who already has clear "every day" evidence of low sweat function. In my opinion, the risks just aren't worth the benefits of seeing just how much the patient does and doesn't sweat. And what a horrible, horrible experience for you, your family, and everyone else involved!

There is another type of "sweat" test, the QSART, that is quite different. They put little suction cups on five places on your body (legs and arms) and prick the skin in those areas with a little acetylcholine (a hormone that provokes sweating). For some patients, the test causes modest discomfort in those areas; for others, it is barely noticeable. But with electronic tracings, the doctor can tell how the autonomic system is responding. In particular, this test can indicate whether there is an underlying small fiber neuropathy.

Based on this test (and all of the clinical findings), my son's neurologist was quite comfortable diagnosing a small fiber neuropathy. He told us, in fact, that many biopsies fail to confirm a small fiber neuropathy because it is hit or miss whether the biopsy happens to come from an affected area. And some people with small fiber neuropathy have heightened pain responses. This is true of my son, so the doctor worried about him developing permanent pain at any biopsy site.

Just a few further thoughts on these different tests!

[nunntrio]

I feel that I should share this: the absolutely WORST POTS experience of all time for me was thermoregulatory sweat test, which had at Mayo, MN. They cover you with powder and put in you a box, like a coffin, with loud music to distract you. Then they turned up the heat big time. They had told me that it would be only so many minutes, but soon I realized that it was past the time and I was STILL IN THE BOX and about to syncope.

I started beating and begging for help when I noticed that something massive was going on in the room. Eventually, they came and told me they were "sorry" but that they had an emergency and LEFT ME IN TOO LONG! I could not breath and was unable to comprehend how it was supposed to be so blasted hot in that box.

There are no words for how sick I was, but since I was lying down, I didn't syncope.

When they open the box, they check out the powder to see where you did or didn't sweat and wash you off. By that time, they said "we are walking you out but do NOT look across the room to the other box." Duh, I looked.

They hadKILLED THE LADY in the other box from the malfunction of both hot boxes. My husband, sitting in the lobby, went up to the desk and asked where am I in that it was taking way too long. Then he sees them wheel a body bag out of my room. He went totally hysterical as they made him wait to tell him which patient died in the BOX!

This is a TRUE STORY. I asked where was my IV for sweating up a storm and being put in a defective box, and they REFUSED to give me on. As my husband wheeled me to the room, of course, I passed out cold. THEN I had terrible suffering (throwing up, all over severe pain, severe chest pain, etc.) until we waited for them to give me an IV.

If you gave me a million dollars, I would not allow Mayo to test me for anything ever again.

And natch, I had POTS and a negative result from the box test. Hope that helps.

Wow, that is a truely awful story. I am sorry that you had to go through this. It sounds like a fairly simple test with little risk but that is obviously not the case. Thank you for sharing your story.