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Plasma catecholamines in HTN? What do I do with this?


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So a provider order a plasma catecholamine on a new patient which I had just started lisinopril on (72 y/o M with BP 180/100 - hasn't been to doc in years). Plasma epinephrine comes back elevated 3x upper normal (neg norepi/dopamine). I've never ordered this, I don't know how to interpret this, I can't find any good info on this panel.

 

My initial instinct is to get a 24 hr urine frac catecholamine/metanephrines to r/o pheo. But my initial plan was to try 2 HTN meds before further testing.

Somebody hit me on the head with an education hammer or provide me with a good link/suggestion, please. thanks :=-0:

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We usually do a serum metanephrines if we suspect a pheo. A plasma epi sounds very "instantaneous" -- kind of like a serum glucose rather than an A1c. I would add another anytihypertensive and see what happens rather than chase the zebra, unless there are other symptoms besides a pressure of 180/100.

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Consider a 24 hr BP monitor to document/exclude BP spikes in an otherwise normotensive, or less severe hypertensive pt.. If you treat an arbitrary elevated reading you can create a hypotensive state by reactively increasing meds. If in-house, sono/CT adrenals.

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Interesting discussion. Unfortunately lots of people who have not been taking antihypertensives come in with pressures like that and more. We typically get them back weekly until they are under control. It is people who don't improve that go off for additional testing. It is, however, not all that common for a true hypertensive can be controlled on a single agent. And yes, one pressure doesn't make a hypertensive.

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No one thus far has brought up a critical question regarding the severe category BP reading and the need to treat versus obtain additional dx information. If they took a BP they most likely checked the other vitals. What was the HR with this reading? It is for this very reason that I also ask folks who are felt to be reliable patients to not only check home BP readings, but to also note the HR. If someone has a pheo to the point of elevating their BP significantly they should also see a corresponding increase in HR.

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I want to clarify my last post a bit. The plasma catecholamines are more sensitive than the 24hr urine catecholamines but I don't think it is considered very useful these days so I don't know why it would have been ordered up front. I checked Up-to-date, which seems to agree. The 24hr urine for cat/met would provide a better picture. Plasma metanephrines would be useful if suspicion is high(which you don't think it is at this point).

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No one thus far has brought up a critical question regarding the severe category BP reading and the need to treat versus obtain additional dx information. If they took a BP they most likely checked the other vitals. What was the HR with this reading? It is for this very reason that I also ask folks who are felt to be reliable patients to not only check home BP readings, but to also note the HR. If someone has a pheo to the point of elevating their BP significantly they should also see a corresponding increase in HR.

 

All other vitals in WNL. His pulse has been in the 70s for multiple visits and BP measurements at home have been in the 170s after lisinopril and cutting down on his caffiene intake. Just saw him today, put him on hctz 12.5 and will see him again in a week or 2 to see how he's doing. Already did a ecg that was nsr, no LVH apparently. I'm not planning on looking for pheo, but now that I have this plasma epi... Well, I'm not going to look for pheo unless he can't be controlled with 3 anti-HTN rx's.

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Hope this helps:

 

http://labtestsonline.org/understanding/analytes/catecholamine/tab/sample

 

Catecholamines testing is primarily used to help detect or rule out pheochromocytomas in symptomatic people. It also may be ordered when a pheochromocytoma is removed to monitor for recurrence. The blood test is most useful when the person has persistent hypertension or is currently experiencing an episode of hypertension. This is because the hormones do not linger in the blood; they are used by the body, metabolized, and/or excreted. Urine catecholamines testing measures the total amount of catecholamines released in 24 hours. Since the hormone levels may fluctuate significantly during this period, the urine test may detect excess production that is missed with the blood test. Blood and urine tests may be ordered together or separately to look for excessive amounts of both catecholamines and their metabolites.

 

 

Since these tests are affected by drugs, foods, and stresses, false positive tests can occur. For this reason, catecholamine testing is not recommended as a screen for the general public. Doctors will frequently investigate a positive result by evaluating a person's stresses, work to alter or minimize any influences, and then repeat the test to confirm the original findings.

 

 

Occasionally, the tests may be ordered on an asymptomatic person if an adrenal or neuroendocrine tumor is detected during a scan conducted for another purpose or if the person has a strong personal or family history of pheochromocytoma.

 

 

When is it ordered?

Catecholamines testing is ordered when a doctor either suspects that a person has a pheochromocytoma or wants to rule out the possibility. He may order it when someone has persistent or recurring hypertension along with symptoms such as headaches, sweating, flushing, and rapid heart rate. It may also be ordered when a person has hypertension that is not responding to treatment as people with pheochromocytomas are frequently resistant to conventional therapies.

 

 

Occasionally, the test may be ordered when an adrenal tumor is detected incidentally or when someone has a family history of pheochromocytomas. It may also be used as a monitoring tool when a person has been treated for a previous pheochromocytoma.

 

 

 

 

What does the test result mean?

 

 

 

 

Since the catecholamines test is sensitive to many outside influences and pheochromocytomas are rare, a doctor may see more false positives with this test than true positives. If a symptomatic person has large amounts of catecholamines in her blood and/or urine, further investigation is indicated. Serious illness and stress can cause moderate to large temporary increases in catecholamine levels. Doctors must evaluate the person as a whole - her physical condition, emotional state, medications, and diet. When interfering substances and/or conditions are found and resolved, the doctor will frequently re-test the person to determine whether the catecholamines are still elevated. The doctor may also order blood and/or urine metanephrine testing to help confirm his findings and imaging tests, such as an MRI, to help locate the tumor(s).

 

 

If catecholamine levels are elevated in a person who has had a previous pheochromocytoma, then it is likely that either treatment was not fully effective or that the tumor is recurring.

 

 

If the concentrations of catecholamines are normal in both the plasma and urine, then it is unlikely that a person has a pheochromocytoma. Pheochromocytomas do not necessarily produce catecholamines at a constant rate, however. If the person has not had a recent episode of hypertension, their blood and urine concentrations of catecholamines could be at normal or near normal levels even when a pheochromocytoma is present.

 

 

 

 

Is there anything else I should know?

While plasma and urine catecholamines testing can help detect and diagnose pheochromocytomas, they cannot tell the doctor where the tumor is, whether there is more than one, or whether or not the tumor is benign (although most are). The amount of catecholamines produced does not necessarily correspond to the size of the tumor. This is a physical characteristic of the tumor tissue. The total amount of catecholamines produced will tend to increase, however, as the tumor increases in size.

 

 

A variety of medications can interfere with catecholamines testing. However, it is important to talk to the doctor before discontinuing any prescribed medications. He will work with the person being tested to identify potentially interfering substances and drug treatments and to determine which of them can be safely interrupted and which must be continued for the person's well-being. Some of the substances that can interfere with catecholamines testing include: acetaminophen, aminophylline, amphetamines, appetite suppressants, coffee, tea, and other forms of caffeine, chloral hydrate, clonidine, dexamethasone, diuretics, epinephrine, ethanol (alcohol), insulin, imipramine, lithium, methyldopa (Aldomet), MAO (monoamine oxidase) inhibitors, nicotine, nitroglycerine, nose drops, propafenone (Rythmol), reserpine, salicylates, theophylline, tetracycline, tricyclic antidepressants, and vasodilators. The effects of these drugs on catecholamines results will be different from person to person and are often not predictable.

 

 

While 90% of pheochromocytomas are found in the adrenal glands, most of the remaining 10% are typically found in the abdominal cavity. The World Health Organization uses the term "extra-adrenal paraganglioma" to describe catecholamine-producing tumors that are not located in the adrenal glands.

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