Catecholamines - urine

Alternative names

Definition

How the test is performed

Catecholamines can be measured in the blood or urine.

A 24-hour urine sample is needed. Your health care provider will instruct you, if necessary, to discontinue drugs or activities that may interfere with the test (see "How to prepare for the test").

• On day 1, urinate into the toilet upon arising in the morning.
• Collect all subsequent urine (in the special container) for the next 24-hours.
• On day 2, urinate into the container in the morning upon arising.
• Cap the container. Keep it in the refrigerator or a cool place during the collection period. Label the container with your name, the date, the time of completion, and return it as instructed.

For an infant:
Thoroughly wash the area around the urethra (the hole where urine flows out). Open a urine collection bag (a plastic bag with an adhesive paper on one end), and place it on your infant. For males, the entire penis can be placed in the bag and the adhesive attached to the skin. For females, the bag is placed over the labia. Place a diaper over the infant (bag and all).

The infant should be checked frequently and the bag changed after the infant has urinated into the bag. For active infants, this procedure may take a couple of attempts since lively infants can displace the bag. The urine is drained into the container for transport to the laboratory.

Deliver it to the laboratory or your health care provider as soon as possible upon completion.

How to prepare for the test

How the test will feel

Why the test is performed

The test is used primarily to screen for, diagnose, and monitor treatment of pheochromocytoma or neuroblastoma .

Catecholamines are chemically similar small molecules derived from the amino acid tyrosine. The major catecholamines are dopamine , norepinephrine , and epinephrine (old name: adrenalin).

Dopamine is a neurotransmitter (a chemical used to transmit impulses between nerve cells) found mainly in the brain. Norepinephrine is the primary neurotransmitter in the sympathetic nervous system (controls the "fight or flight" reaction) and is also found in the brain. Epinephrine is not only a brain neurotransmitter, but also a major hormone in the body.

Epinephrine is secreted from the adrenal medulla in response to low blood glucose , exercise, and various forms of acute stress (in the latter case, the brain stimulates release of the hormone). Epinephrine causes a breakdown of glycogen to glucose in liver and muscle, the release of fatty acids from adipose tissue, vasodilation of small arteries within muscle tissue, and increases the rate and strength of the heartbeat.

All of the catecholamines are metabolized by their target tissues or by the liver to become inactive substances that appear in the urine:

• dopamine becomes HVA
• norepinephrine becomes normetanephrine and VMA
• epinephrine becomes metanephrine and VMA

Normal Values

• VMA: 2 to 7 mg/24-hours
• epinephrine: 0.5 to 20 mcg/24-hours
• norepinephrine: 15 to 80 mcg/24-hours
• dopamine: 65 to 400 mcg/24-hours
• metanephrine: 24 to 96 mcg/24-hours (some laboratories give the range as 140 to 785 mcg/24-hours)
• normetanephrine: 75 to 375 mcg/24-hours
• total urine catecholamines: 14 to 110 mcg/24-hours

Note: mg/hour = milligrams per hour; mcg/hour = micrograms per hour.

What abnormal results mean

1. acute anxiety
2. ganglioblastoma (very rare)
3. ganglioneuroma (very rare)
4. neuroblastoma (rare)
5. pheochromocytoma (rare)
6. severe stress

• multiple endocrine neoplasia (MEN) II

What the risks are

Special considerations

Update Date: 8/18/2003