Catecholamines, plasma and urine

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Also known as: Dopamine; adrenaline (epinephrine); noradrenaline (norepinephrine); free urine catecholamines

At a Glance

Why Get Tested?

To help diagnose or rule out a phaeochromocytoma or other neuroendocrine tumour

When to Get Tested?

If you have symptoms of persistent or episodic high blood pressure such as severe headaches, rapid heart rate and sweating

Sample Required?

A 24-hour urine sample (collected into a bottle containing a small amount of acid) or possibly a blood sample taken from a vein in the arm

Note: These tests are affected by certain drugs, foods, and stresses. Inform your doctor of any medicines you are taking and follow any instructions you are given for things to do or foods to avoid before sample collection.

Test Preparation Needed?

You may be asked to lie down and rest quietly for 15-30 minutes prior to sample collection, and your blood may be collected while you are lying down. In other circumstances, you may just be seated upright with little or no rest time before the sample collection.

The Test Sample

What is being tested?

Catecholamines are a group of similar hormones produced in the medulla (central portion) of the adrenal glands. The adrenal glands are small, triangular organs which sit on top of each kidney. The main catecholamines are dopamine, adrenaline (epinephrine), and noradrenaline (norepinephrine). These hormones are released into the bloodstream in response to physical or emotional stress. They help transmit nerve impulses in the brain, increase the release of glucose and fatty acid into the blood (for energy), widen the small air passages in the lungs, and widen (dilate) the pupils of the eye. Noradrenaline also reduces the size blood vessels (increasing blood pressure) and adrenaline increases heart rate and metabolism.

After completing their actions, the hormones are metabolised to form inactive compounds. Dopamine becomes 3-methoxytyramine (3-MT) and homovanillic acid (HVA), noradrenaline changes to normetanephrine and hydroxymethylmandelic acid (HMMA) (also called vanillylmandelic acid (VMA)), and adrenaline becomes metanephrine and HMMA. Both the hormones and their breakdown products (metabolites) are removed in the urine.

Normally, catecholamines and their metabolites are present in the body in small, varying amounts that only increase greatly during and shortly after a period of stress. Phaeochromocytomas and other neuroendocrine tumours, however, can produce large amounts of catecholamines, resulting in greatly increased levels of the hormones and their metabolites in both the blood and urine. This can cause persistent high blood pressure and/or bouts or episodes of very high blood pressure, resulting in severe headaches, palpitations, sweating, sickness, anxiety, and tingling in the fingers and toes.

About 80-85% of phaeochromocytomas are found in the adrenal glands. While a few are cancerous, most are benign meaning that they do not spread beyond their original location, although most do continue to grow. Left untreated, the symptoms may get worse as the tumour grows and, over a period of time, the high blood pressure that the phaeochromocytoma causes may damage body organs, such as the kidneys and heart, and increase the risk of a stroke or heart attack.

Urine and plasma catecholamine and catecholamine metabolite testing can be used to help detect the presence of phaeochromocytomas. It is important to diagnose and treat these rare tumours because they cause a potentially curable form of high blood pressure.  Phaeochromocytomas are responsible for high blood pressure in a very small proportion of individuals (approximately 0.1-0.6%). In most cases, the tumours can be surgically removed and/or treated to reduce the amount of catecholamines being produced and to reduce or remove symptoms and complications.

Catecholamine testing measures the amount of adrenaline, noradrenaline, and dopamine in the plasma or urine. Increasingly laboratories are measuring the catecholamine metabolites, metanephrine and normetanephrine in urine or plasma as well, as recent evidence suggests they are more reliable tests because they are continually produced by the tumor.

The plasma catecholamine test measures the amount of hormones present at the moment of collection, while the urine test measures the amount excreted over a 24-hour period.

How is the sample collected for testing?

For the 24-hour urine collection, all of your urine should be saved for a 24-hour period into a bottle containing a small amount of acid. This helps preserve the urine sample. It is important that the sample is stored cool in a refrigerator during this period, and that you write down the time and date that you started and finished the collection on either the collection bottle or the laboratory request form.

Blood catecholamines are collected by putting a needle into a vein in your arm.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

You may be asked to lie down and rest quietly for 15-30 minutes prior to sample collection, and your blood may be collected while you are lying down. In other circumstances, you may just be seated upright with little or no rest time before the sample collection.

The Test

Common Questions

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.