Pheochromocytoma question

[fbc3000]

My question concerns the symptoms and diagnosis of pheochromocytoma.   Several years ago, I developed several symptoms such as flushing, fast heart rate, exercise intolerance, and other symptoms suggestive of possible pheo.  We did a blood test offered by NIH and it showed normetanephrine over 3,800 pg/dl and norepinephrine over 450 pg/dl.   Because plasma free metanephrine was normal, the researcher noted on the blood test that it wasn't likely a pheo.   I have never had these tests again but I have been forced to take a CCB for several years without knowing why.   Off of the CCB, I develop exercise hypertension at times and have a hyperadrenergic situation.   Oddly, at rest my BP is very low and I have bradycardia.  I am also now developing other health problems exacerbated by exercise and I am wondering if a pheo could actually be a possibility.  

Is it normal to have plasma normetanephrine levels this high?  Do people with pheos sometimes have normal plasma free metanephrines but abnormal normetanephrines?

Thanks!  

[fbc3000]

I just wanted to update this thread.  I had the plasma free metanephrines test recently.  The plasma free metanephrine test was <.20 in the low normal range, but the plasma free normetanephrine was elevated at 1.2 nmol/l.   A later 24-hour urine test was normal, along with a later plasma free metanephrines test.   Not sure what this means, but I think I have excessive elevations in noradrenaline at times for some reason, which follows or exacerbates my other endocrine and autoimmune conditions - Raynauds, UCTD, pituitary disease, adrenal insufficiency, etc.

[fbc3000]

There are plot graphs in the above study showing plasma total normetanephrines for pheo patients in a very similar distribution pattern as the patients with high plasma free normetanephrines and high urine normetanephrines.   Normetanephrines, however measured, appear in the study to be the most sensitive for diagnosing pheos.  Next in line is plasma norepinephrine.

Although most patients with pheos are probably high in both plasma free normetanephrines and total plasma normetanephrines, a point is made that one patient in the study had an isolated result of high plasma total normetanephrines only.   This patient had Von Hippel Lindau disease.  

It seems that patients with high normetanephrines of any kind should probably be followed up with further testing over time to accurately exclude a pheo or other similar disease process, especially when norepinephrine or other values are also above the values typically shown with healthy patients.  

Also, it appears that patients with isolated high total plasma normetanephrines should be screened for kidney disease and any other disease that impairs the body's ability to clear normetanephrine.  

[fbc3000]

If anyone out there is interested in the significance of plasma total normetanephrines versus plasma free normetanephrines, I found the following study helpful:

http://www.eje-online.org/content/162/5/951.full.pdf

[fbc3000]

I just realized that the information in my prior post listed pg/dl when it should have read pg/ml.   The total plasma normetanephrine was over 3,800 pg/ml and the norepinephrine was over 450 pg/ml.  

Thanks!