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Blood Work For Norepinephrine?


Jacquie802
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Hi guys,

Just curious why the doc wants me to sit, stand, etc. while getting my blood drawn..I think he said it is going to measure my norepinephrine, but I'm not sure why it matters the position you are in...Is something released in your blood???? Just very confused!

Jacquie

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Yups indeed- when we change position, our norepinephrine levels often jump way up, which is often what we refer to as that adrenaline rush that helps to cause our POTS symptoms.

There are other similar topics, so i'd suggest doing a search for it. Good luck!

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Guest tearose

Oh yeah, I forgot about this test. This is another diagnostic gem for hyperadrenergic dx.

When you lay down the norepinepherine measures one level, when you sit up, it will respond differently and then when you stand...you will probably reach your highest levels.

I think they have to "save" the bloods and send them to a special lab for this test. Although things have changed since I did this test. Where are you doing this?

best regards, tearose

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It's not just for hyperadrenergic types, though. It can be useful for them to see what your body chemistry is doing in particular.

They might look for other catecholamines besides the NE, too- various hormones and metabolites which might be way off when you're changing position.

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A few years ago, a pair of identical twins who had had POTS for many years were found to have a "loss of function" mutation in the gene that carries the recipe for making the norepinephrine transporter, which is a protein found on the outside of some cells, including nerve and muscle cells (as well as some white blood cells). There was a misspelling in the recipe, so the protein that was made didn't work properly.

In a normal person, about 80% of the norepinephrine (which is a "fight or flight" neurotransmitter and hormone, like adrenaline) released by a nerve cell gets picked back up by the norepinephrine transporters of the cell that secreted it. The other 20% "spills over" into the general circulation. If you have a defective norepinephrine transporter, the norepinephrine stays in the synapse longer, so it can have more of an effect. Plus, more of it "spills over" into the bloodstream. So, if your norepinephrine transporters are malfunctioning, or missing, then you will have higher levels of norepinephrine in your blood than a normal person would, especially when you are standing up. That's why they take samples while you are lying down and standing up.

The loss of function mutation in the twins wasn't found in any unrelated people. Instead, researchers at Baker Heart Institute in Australia have found that the gene for the norepinephrine transporter is normal, but it is accidentally "switched off," so it is not being used to make the norepinephrine transporter. Some of the people with this finding get panic disorder, and some get POTS, and some get both.

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

http://www.mc.vanderbilt.edu/reporter/index.html?ID=1039

http://www.ncbi.nlm.nih.gov/entrez/query.f...l=pubmed_docsum

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Hi,

The testing is going to be done @ Boston Medical Center. :)

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Hi, Jacquie:

Good luck with your norepinephrine testing. I'd be interested to hear what you learn from it. The affect of norepinephrine in POTS has had my attention because I was (and still am) on an SNRI (serotonin norepinephrine reuptake inhibitor) prior to my diagnosis of POTS. My rheumatologist prescribed Cymbalta (the SNRI) for neuropathic pain due to fibromyalgia.

My understanding is a reuptake inhibitor would result in increased amounts of that neurotransmitter in the blood stream because it prevents the inital releasing neuron from absorbing the 80% that lthomas mentioned. I see on the forums that others have had this same drug prescribed for POTS. What I don't completely understand is if those diagnosed have higher blood stream levels of norepinephrine levels to start, why does increasing it help? Is the theory that the presence of more is a sign of the body trying to compensate (rather than a malfunction) and the SNRI boosts that compensatory measure to a functional level?

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Personally, I suspect that blocking norepinephrine reuptake does exactly nothing for a POTS patient. If you don't have norepinephrine transporters to begin with, then you don't have the target that the drug is supposed to work on. That would be like trying to ring a doorbell that isn't even there. Maybe the SNRI is having some sort of an effect by reducing serotonin reuptake. Some SSRIs are relatively activating, so maybe that gives some people some benefit.

When the theory of the norepinephrine reuptake was first suggested by someone on this forum, I asked a friend of mine who does antidepressant research what would happen to someone who doesn't have any norepinephrine transporters. First he said, "No norepinephrine reuptake? How could someone live like that?" I said, "Not well, evidently." He said, "That would be like taking massive doses of some kinds of antidepressant." I said, "No wonder I'm unreasonably cheerful."

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First he said, "No norepinephrine reuptake? How could someone live like that?" I said, "Not well, evidently." He said, "That would be like taking massive doses of some kinds of antidepressant." I said, "No wonder I'm unreasonably cheerful."

^^^That just cracked me up. Thanks for the good laugh and for the explanation. :ph34r:

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great post lthomas. good references. too bad the full text pubmed article is $30 :unsure:

regarding SNRIs and SSRIs - my understanding is that these are usually medications that act only (or mostly) on the brain and not the CNS/ ANS. So for example I take the SNRI Strattera for ADHD because (so the theory goes) my brain doesn't have enough NE. But I have POTS so my blood (plasma) NE is probably too high (I haven't had it tested). I don't have any improvement in POTS when I stop taking Strattera so I'm reasonable sure that it's only acting on my brain, not the rest of my body. A SNRI that acts on the body is probably a bad idea for POTS patients. The opposite would make more sense - a NE reuptake agonist? I wonder if the lady with the NET disorder has the same issue with her brain NE? I guess brain neurons and other nuerons are the same? I think she'd have mental issues besides just POTS if her brain NE was too high.

Jacquie - yes, your body releases norepinephrine (NE) into your blood. The amount of NE depends on a lot of things including body position. Normally, a person's blood NE level increases when they stand but in POTS patients it goes way up much higher than normal.

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