Catecholamines - blood

Alternative names

Definition

How the test is performed

Catecholamines are more often measured with a urine test than with this blood test, although the blood test is sometimes used.

Adult or child:
Blood is drawn from a vein ( venipuncture ), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and cause veins below the tourniquet to distend (fill with blood).

A needle is inserted into the vein, and the blood is collected in an airtight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding .

Infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

How to prepare for the test

Certain foods can increase catecholamine levels including coffee, tea, bananas, chocolate, cocoa, citrus fruits, and vanilla. Avoid these foods for several days prior to the test, particularly if both serum and urine catecholamines are to be measured.

Avoid other interfering factors:

• Acute stress
• Vigorous exercise

Consult your health care provider regarding the need to discontinue potentially interfering drugs. 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.

Never discontinue any medication without first consulting your health care provider.

Infants and children:
The physical and psychological preparation a parent can provide for this or any test or procedure depends on the child's age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:

• Infant test or procedure preparation (birth to 1 year)
• Toddler test or procedure preparation (1 to 3 years)
• Preschooler test or procedure preparation (3 to 6 years)
• Schoolage test or procedure preparation (6 to 12 years)
• Adolescent test or procedure preparation (12 to 18 years)

How the test will feel

Why the test is performed

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

Catecholamines are chemically similar small molecules derived from tyrosine, an amino acid. The major catecholamines are dopamine, norepinephrine, and epinephrine (which used to be called adrenalin).

• Dopamine is a neurotransmitter (a chemical used to transmit impulses between nerve cells), mainly found in the brain.
• Norepinephrine is the primary neurotransmitter in the sympathetic nervous system (controls "fight or flight" reactions) 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 . Epinephrine causes several responses:
  • A breakdown of glycogen to glucose in the liver
  • The release of fatty acids from fat tissue
  • Vasodilation of small arteries within muscle tissue
  • Increase in rate and strength of the heartbeat

Normal Values

Epinephrine: 20 ng/100 mL

Norepinephrine: 60 ng/100 mL

Note: ng/mL = nanograms per milliliter

What abnormal results mean

• Acute anxiety
• Ganglioblastoma (very rare)
• Ganglioneuroma (very rare)
• Neuroblastoma (rare)
• Pheochromocytoma (rare)
• Severe stress

What the risks are

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)
• Multiple punctures to locate veins

Special considerations

The test's accuracy is affected by several foods and drugs as well as such things as physical activity and stress .

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult from some people than from others.

Update Date: 5/20/2003