Catecholamines - urine

Alternative names:

adrenalin-urine test; dopamine-urine test; epinephrine-urine test; homovanillic acid (HVA); HVA; metanephrine; norepinephrine-urine test; normetanephrine; urine catecholamines; urine metanephrine; vanillylmandelic acid (VMA); VMA

How the test is performed:

Catecholamines can be measured in the blood or urine. Catecholamine metabolites are measured in the urine. Therefore, the urine test is performed more frequently than the blood test to determine catecholamine levels.

A 24-hour urine sample is needed.
The health care provider will instruct you, if necessary, to discontinue drugs that may interfere with the test.

• On day 1, urinate into the toilet upon arising in the morning.
• Collect all subsequent urine (in a 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.

Infant:
Thoroughly wash the area around the urethra. 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--lively infants can displace the bag, causing an inability to obtain the specimen. 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:

Certain foods can increase urinary catecholamines, including coffee, tea, bananas, chocolate, cocoa, citrus fruits, and vanilla. Avoid these for several days prior to the test.

Avoid other factors that can affect the test, including acute stress and vigorous exercise.

Consult your health care provider regarding the need to discontinue drugs that can affect the test. Drugs that can increase catecholamine measurements include caffeine, levodopa, lithium, aminophylline, chloral hydrate, clonidine, disulfiram, erythromycin, insulin, methenamine, methyldopa, nicotinic acid (large doses), quinidine, tetracyclines, and nitroglycerin.

Drugs that can decrease catecholamine measurements include clonidine, disulfiram, guanethidine, imipramine, MAO inhibitors, phenothiazines, salicylates, and reserpine.

If the collection is being taken from an infant, a couple of extra collection bags may be necessary.

How the test will feel:

The test involves only normal urination, and there is no discomfort.

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 that are 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 cells), mainly in the brain. Norepinephrine is the primary neurotransmitter in the sympathetic nervous system and is also in the brain. Epinephrine is a neurotransmitter in the brain but is also a major hormone in the body.

Epinephrine is secreted from the adrenal medulla in response to low blood glucose, exercise, and with 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, causes the release of fatty acids from the adiposes, causes the 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 inactive substances that appear in the urine:

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