First of all, both tests are great. If your local area only
offers one of them, take it. If your local area offers both tests, which one is
better? Shall you do both? My personal preference is plasma metanephrines. The
plasma test is convenient and can be done to any patient at any time. The only
small drawback is the blood draw itself. If you really hate needles, the plasma
test could be an issue. The urine test offers no practical advantage over the plasma
test. In theory and in earlier reports, the urine test is less prone to false
positive results. In real clinical practice, the urine test and the plasma test
perform similarly. The urine test is laborious to collect (24-hour urine is
required), not reliable in patients with kidney problems, and hard to do in
children. Lastly, the urine test results have to be corrected by urine creatinine.
I have seen patients who passed ~5 liters of urine in 24 hours; of course the
metanephrines levels are higher simply because of the large urine volume. The results
usually are more accurate after they are divided by the total amount of
creatinine in the urine. Again I want to emphasize that I personally don’t see
why one would need the urine metanephrines for pheo diagnosis if plasma test is
available. There is also no need to do both tests.
Dr. Pheo
Hi Dr Pheo,
ReplyDeleteShould the urine collection container have a preservative added?
Also, do you agree with some of the recent papers that put the chance of a pheo with NF1 and high bp at up to 50%?
There are also a few published case histories where people have had a pheo without ever getting a positive test result - is this happening more often now?
Many thanks for your blog, it is very much appreciated.
Dear Debbie Sutherland,
ReplyDeleteThanks for your compliments.
The urine preservative is preferred but probably not essential.
I think the rate of pheo is lower than 50% in patients with NF1 and hypertension.
People with small pheos can have normal tests. Extra-adrenal pheos (paragangliomas) may be non-functional as well. Sizable adrenal pheos are mostly functional and associated with high test results.
Dr. Pheo
Many thanks for your reply. My 24hr collection has come back negative but my GP has no idea what's causing episodes of bp spikes with tachycardia and arrythmia and migraine. Am waiting to see an endocrinologist but the wait list is long!
ReplyDeleteI have severe muscle weakness and only just dx with NF1 even though in my 50's.
Any suggestions of what differential dx could be looked at would be appreciated.
Dear Debbie Sutherland,
DeleteSorry but I don't know. There are many differential diagnoses of pheo. Please discuss with your local doctors.
Dr. Pheo
Dr. Pheo,
ReplyDeleteWonderful blog. Thank you for your time and so much informative knowledge.
When I was a child (12 years old or so) doctors thought I had a Pheo based on some lab results...they couldn’t find one on my adrenals so no further test were done. It’s been 20 years and I can’t verify what the past labs were. Fast forward to now (42 years old) , I have been diagnosed with POTS Syndrome which you know has very similar symptoms. I just panic out of the blue, often after meals. I have abdominal bloating, can’t regulate body temp, palpitations, blood pressure spikes with movement and standing. Have passed out twice. All cardio test are negative. AC1 is good but my BS spikes to 180 all the time (has been In the 200’s on occasions). I strongly believed I could have a Pheo but MET labs are all negative now. Abdominal MRI showed the following:
Small mildly T2 hyperintense foci in the spleen are nonspecific but could represent cysts or hemangiomata. Hepatic size is within limits of hepatic signal is normal 0.7 cm on 72 hyperintense focus is seen in right hepatic lobe.
Adrenal glands and kidneys appear normal.
Impression: subcentimeter T2 foci in the liver and spleen likely represent cysts or hemangiomata. Ultrasound confirmation recommended.
Could these cysts possibly be pheo’s?
Dear Just SWEET Freeborn BOYS!,
DeleteIt is clear that you don't have pheo. Cysts are common in liver and spleen; they are usually not a health problem.
Dr. Pheo
Dr Pheo,
ReplyDeleteI have recently been tested for theochromocytoma because I've been having spikes in blood pressure. I have two recommended blood tests and the 24 hour urine test all of which came back with high levels and indicating pheo. I was then sent for a CT scan which I had to drink a solution before and die was injected through IV during the scan. I was told no tumor showed in the scan. So no pheo. Is it possible that it would not show in CT scan. I'm still getting high bp spikes and day to day bp still high. Should I be concerned?
Dear Unknown,
DeleteThis will depend on how high your test results actually are. Please let me know the exact test results and the normal range of the tests.
Dr. Pheo
I am under surveillance for positive SDHB mutation
ReplyDelete10 family members have positive mutations and 3 with active pheo’s. In the past my urine and blood has been
Normal but recently I had plasma Mets done and first lab came back with low catecholamines...so doc re ordered....now this one has high dopamine —250!( should be <20)....should I be concerned ?
Dear Kevinandlaurafairley,
DeleteAn isolated and slightly high dopamine level should not be a concern.
Dr. Pheo
Hello,
ReplyDeleteI have MEN2A. I'm always nervous and sometimes I have anxiety.
I have the following results with 24h urine test:
Normetanephrine: 407 , ref range 88-444
Metanephrine: 245, ref range 85-345
All the other values are normal, but I'm afraid because I did very low urine in the last spot (second morning) because I was nervous. I'm thinking that if I had expelled the urine normally, the normetanephine value would be above the uppercut value.
My doctor says its all ok but I'm worried about this
Dear Megan,
DeleteI agree with your doctor that you probably don't have an active pheo. In people with MEN2A or 2B, the metanephrine level (more important than normetaneprhine) is the one to watch for.
Dr. Pheo