Type of Pots

[kelly1258]

How do I find out what type of Pots my daughters have?

[supineallthetime]

I'm not certain but I think this requires close testing by one of the few Autonomic Specialists that are out there, like at the key autonomic centers... Vanderbilt, Cleveland Clinic, Mayo MN, etc.

I believe there are no certainties even with expert testing (except for the very very rare situations like NET deficiency) but they can "characterize" things by looking for pooling, flow measures, signs of peripheral neuropathy, measuring catecholamines in various postures, etc.  Once they characterize the disorder, they may have a jump start on treatment approaches but it is still largely trial & error.

I've not been through that process, this is just what I gather from reading other peoples stories... perhaps someone who has had that degree of testing can comment...

[kelly1258]

I have been looking into NET deficiency .  How do you test for this?

[supineallthetime]

Not sure if there is a "clinical" procedure to do so.  My understanding is that its in the "research realm".  Here are some articles that kind of cover it from a research perspective.  They seem to have measured buildup or clearance of norepinephrine... and also examined related genetic markers.  I'm only operating at an "overview" level of understanding at best here!

http://content.nejm.org/cgi/content/full/342/8/541

http://www3.interscience.wiley.com/journal/120754485/abstract

Even though the first of those two was from 2000, I believe this is all still considered theoretical in terms of pinning down a cause for some POTS/OI folks (as the article mentions, this relates to a subset of those with the syndrome).  My understanding is that it offers a hypothesis to "Hyperadrenergic POTS" as opposed to that which is secondary to a neuropathy or other potential (or theoretical) causes.

[Heiferly]

It depends heavily on who your doctor is that is managing her POTS.  

Dr. Grubb in Toledo, for example, divides POTS cases into two broad categories:  PD [partial dysautonomic] and H [hyperadrenergic/hyperadrenic].  He has suggested that there may be subcategories beneath this, but that further research is needed to explore this.

Dr. Stewart in New York, however, divides POTS cases into three categories:  low-flow, normal-flow, and high-flow. One of his categories may roughly correlate to Dr. Grubb's H-POTS category, but the two paradigms aren't entirely parallel and at any rate, that discussion is beyond the scope of this post.  

You may also hear terms such as "florid POTS," "late POTS," that act as modifiers which are used by some diagnosticians and eschewed by others.

Still other specialists suspect that POTS is not a single entity at all and prefer not to pigeon-hole their patients, offering a more descriptive diagnosis instead.  

Looking at it from that perspective, you might consider the "type" of POTS to be one where syncope is comorbid or not, one with a certain percentage of blood pooling in dependent limbs/splanchnic bed in the upright position, one with partial or complete sympathetic denervation of the legs (autonomic neuropathy), etc.

In early 2000, a small number of patients with genetic defects with norepinephrine transporters were identified, and this opened up a new subcategory of POTS patients.  Research into this is still ongoing, though it is thought that the relative percentage of POTS patients this pertains to is small.

This also brings up the point of primary vs. secondary POTS.  A finding of denervation/neuropathy could lead to further testing which might reveal underlying autoimmune disease, in which case you would have a primary diagnosis of whichever autoimmune disease is found and a diagnosis of Secondary POTS.  POTS can be secondary to a host of different causes, some of which are more difficult to detect than others.  


Is there a specific classification you're seeking?  If so, I may be able to tell you what tests would be needed to make that determination.

[Heiferly]

Sorry, I hadn't read your post about NET deficiency when I replied.  Vanderbilt was working on the test as of March, if I understand this correctly:

http://vanderbilt.technologypublisher.com/technology/1802

You may want to inquire at the contact information listed there.  Here's the article on which gene they identified:

http://www.ncbi.nlm.nih.gov/pubmed/12805287

Let us know if you find out anything!