A test for catecholamines measures the
amount of the
hormones epinephrine, norepinephrine, 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"
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),
metanephrine, and normetanephrine. Metanephrine and normetanephrine also may be measured during a catecholamine test.
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 intestines and increase blood going to the
major organs, such as the brain, heart, and kidneys.
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 measures 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
- Amines. These are found in bananas, walnuts, avocados,
fava beans, cheese, beer, and red wine.
- Any foods or fluids with
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