A test for catecholamines measures the amount of the hormones epinephrine, norepinephrine, metanephrine, and dopamine in the blood. These catecholamines are made by nerve tissue, the brain, and the adrenal glands. Catecholamines help the body respond to stress or fright and prepare the body for "fight-or-flight" reactions.

The adrenal glands make large amounts of catecholamines as a reaction to stress. The main catecholamines are epinephrine (adrenaline), norepinephrine (noradrenaline), and dopamine. They break down into vanillylmandelic acid (VMA) and metanephrine.

Catecholamines increase heart rate, blood pressure, breathing rate, muscle strength, and mental alertness. They also lower the amount of blood going to the skin and increase blood going to the major organs, such as the brain, heart, and kidneys.

Certain rare tumors (such as a pheochromocytoma) can increase the amount of catecholamines in the blood. This causes high blood pressure, excessive sweating, headaches, fast heartbeats (palpitations), and tremors.

Why It Is Done

A catecholamine test is done to help diagnose a tumor in the adrenal glands called a pheochromocytoma. Catecholamine levels in the blood can change quickly, so it may be hard to find high values in a single blood sample. But a special compound, metanephrine, may be found in the blood, which may mean a pheochromocytoma is present. Doctors may want to do a urine test that shows catecholamine levels over 24 hours.

How To Prepare

You may be asked to avoid the following foods and fluids for 2 to 3 days before having this test:

• Caffeine, such as coffee, tea, cocoa, and chocolate
• Amines. These are found in bananas, walnuts, avocados, fava beans, cheese, beer, and red wine.
• Any foods or fluids with vanilla
• Licorice
• Aspirin

You may be asked to not eat or drink anything for 10 hours before this test. Do not use tobacco for 4 hours before the blood test.

Many medicines may change the results of this test. Be sure to tell your doctor about all the nonprescription and prescription medicines you take.

Your doctor may ask you to stop certain medicines, such as blood pressure medicines, before the test. Do not take cold or allergy remedies, including aspirin, or nonprescription diet pills for 2 weeks before the test.

Having a blood sample taken can cause stress. This may increase catecholamine levels. Be sure to keep warm, because being cold can also increase your catecholamine levels. Ask for a blanket if you feel cold.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?) .