Plasma norepinephrine levels and significance of heart rate rise during tilt

[Bamboozlem]

Hi,

I have EDS Hypermobile (diagnosed last year) and POTs (diagnosed this Summer).

First question: understanding plasma norepinephrine levels.
Blood levels were taken in the supine position, and after 5 and 10 minutes of orthostatic stress.
Here are results from the lab chemistry test:
Epinephrine 0.6
Norepinephrine 5.8 - flagged as high
Cortisol 199
Phosphate 3.4 - flagged as low

Just curious about Norepinephrine as 5.8
I've been looking online, and see 80-​520 pg/mL is the normal range for plasma norepinephrine, so I'm not sure what 5.8 means, or what range it's using.

Second question: is there any significance in how high your heart rate jumps?
My resting heart rate in supine position was 53 beats per minute.
During tilt, it rose to 117 beats per minute, and I was tilted down after 15 minutes.
It jumped 64 beats and I was diagnosed with "mild" POTs, but the thing is, while I recognize I am high functioning, I don't feel that it's "mild".
I guess my question is - what does it matter, in terms of symptoms, of how high your heart jumps? Is it there any significance to it?  i.e.. the difference between jumping over  30 vs. over 40 vs. over 50, etc.?

Any info greatly appreciated.

[Heiferly]

Hey. These are great, insightful comments. In regard to the reference range, they vary by lab, so the best thing for you to do is to call the lab where you had the testing done and ask them what their reference range is! They should be able to tell you that easily.

As for the heart rate increment and telling "mild" POTS from more severe forms, I hope I can answer that well for you. The truth is, the amount of heart rate increase upon upright tilt does not correlate well with the severity of the symptoms from one patient to another; however, my observations indicate that it's quite likely that higher HR increment correlates to worse symptoms when comparing one day to another in the same patient with POTS. So, you may be able to tell you're having a worse day because your heart rate is going higher today than it did any day in the past week, for example, but comparing your HR to that of another patient probably won't be very telling about whose case is more "severe."

I know this is a very touchy subject, because the truth is that "mild" POTS can still be very troubling and disabling. If you're sick enough to meet the criteria to be diagnosed with POTS, you're pretty sick, especially during flare-ups. However, there is a system for rating the different "grades" of POTS that is based on how congestive heart failure is graded. You can find that in Table 1 of the following PDF:

http://www.dynakids.org/Documents/pots_article2.pdf

I suspect that some physicians view Grade II as "mild" POTS and Grade III as "severe" POTS. Grade I probably only applies to a minority of POTS patients, such that it would be regarded as "extremely mild" POTS. Notice how none of these "grade" descriptions are very descriptive of what symptoms are experienced by the patient. This is merely a system for roughly classifying the level of disability that results from the symptoms. Moreover, with so few categories in this classification system, a LOT of differences are too "fine-toothed" to be differentiated by this system.

At any rate, that's my guess as to what they were referring to when saying you have "mild" POTS. I wouldn't be terribly concerned about it, so long as you're not applying for disability based on that. If you are homebound/bedbound by your condition and unable to keep meaningful employment, that's definitely something to discuss with your doctor.

Let me know if you have further questions.
-H.

[Red_Star]

I did find one normal plasma norepinephrine reference range listed as: 0.150 to 0.350 ng/mL. I'm not sure but it would make sense the higher your heart rate is the worse the condition is.