Catecholamines - blood
Alternative names:
adrenalin-test; dopamine; epinephrine-test; norepinephrine
How the test is performed:
Catecholamines can be measured in the blood or urine. Although the urine test is most often performed, serum catecholamines can be measured.
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 restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood). A needle is inserted into the vein, and the blood is collected in an air-tight 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 urinary catecholamines including coffee, tea, bananas, chocolate, cocoa, citrus fruits, and vanilla. Avoid potentially-interfering foods for several days prior to the test, particularly if both serum and urine catecholamines are to be measured.
Avoid other interfering factors: Consult your health care provider should be consulted 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.
Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, 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:
How the test will feel:
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
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 the release of the hormone). Epinephrine causes a breakdown of glycogen to glucose in the liver, causes the release of fatty acids from the adipose (fat) tissue, causes the vasodilation of small arteries within muscle tissue, and increases the rate and strength of the heart beat.
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