Adrenomedullary Hormone Tests Health Article

Precautions

There are no notable precautions with either blood or urine tests for adrenomedullary hormones. Physicians will determine if restrictions for the tests are appropriate for patients being treated with medications for high blood pressure or heart disease. When blood is used, universal precautions should be followed for the prevention of transmission of bloodborne pathogens.

Preparation

Physicians will instruct patients to discontinue use of certain medications for up to two weeks before the test or will write orders to this effect for patients in nursing facilities. Drugs that may increase catecholamine levels include caffeine, nicotine, levodopa, lithium, amino-phylline, clonidine, erthromycin, insulin, methyldopa, tetracyclines, and nitroglycerin. Drugs that may decrease catecholamine levels include clonidine, imipramine, MAO inhibitors, phenothiazines, salicylates, and reserpine. The patient should fast (nothing to eat or drink) for 10 to 24 hours before the blood test and should cease smoking for 24 hours before testing. Other restrictions may be required either by individual physicians or by the laboratory, depending on the tests requested. Vigorous physical exercise and emotional stress should be avoided before the test to prevent alteration of test results by increasing secretions of epinephrine and norepinephrine.

The clinical laboratory will provide instructions and containers for patients collecting their own 24-hour urine samples. Catecholamines and their metabolites are rapidly degraded above pH 2.0. Therefore, 10 mL of 6N hydrochloric acid or concentrated sulfuric acid will be present in the container. Patients should be advised to avoid touching the preservative in the collection container. If the preservative comes in contact with the skin, the area should be rinsed with water immediately. Collection should begin in the morning on any day except Friday or Saturday to ensure that samples will be delivered to the laboratory on a work day. Urine samples must be refrigerated continuously in the patient's home or in the nursing facility. The specimen should be delivered to the laboratory promptly at the end of the 24-hour period.

Aftercare

Following venipuncture for blood plasma hormone tests, the laboratory technologist, nurse, or phlebotomist drawing the sample should inspect the venipuncture site to make sure that the wound has closed and no bleeding is present. The site should be covered with an adhesive bandage. There is no notable aftercare for patients under-going 24-hour urine hormone tests. Patients can be reminded to resume foods and medications that were restricted prior to testing.

Complications

Complications from drawing blood are minimal and may include slight bleeding from the venipuncture site, fainting, or lightheadedness after the blood sample is drawn. Blood may accumulate under the puncture site (hematoma) if pressure is not applied to the site immediately after drawing blood. There are no complications for the urine test, although patients must avoid touching the preservative in the collection containers.

Results

Reference ranges are laboratory-specific and vary with age and according to the test methodology used. Normal values for blood and urine tests are different. High performance liquid chromatography (HPLC) is the most common test method. Other methods especially spectophotometric and fluorometric determinations are less specific and give higher results. Urinary levels are influenced by renal function and it has become customary to report urinary catecholamines and their metabolites per gram of creatinine excreted especially when a random urine is used. Typical adult values for HPLC blood and urine tests follow.

Reference ranges for blood plasma hormone levels:

• Supine (lying down): Epinephrine less than 50 picograms per milliliter (pg/mL), norepinephrine less than 410 pg/mL, and dopamine less than 30 pg/mL.
• Standing: Values for blood specimens taken when the subject is standing are higher than the ranges for supine posture for epinephrine (less than 140 pg/mL) and norepinephrine (less than 1700 pg/mL), but not for dopamine.

Reference ranges for urine hormone levels:

• Epinephrine: 0.5 to 20 micrograms per 24 hours (mcg/24 hrs) or 0 to 20 micrograms per gram creatinine.
• Norepinephrine: 15 to 80 mcg/24 hrs or 0-45 mcg per gram creatinine.
• HVA: 65 to 400 mcg/24 hrs or 0 to 8 mg per gram creatinine.
• Total catecholamines: 14 to 110 mcg/24 hrs.
• VMA: 2 to 7 milligrams(mg)/24 hrs or 0 to 6 mg per gram creatinine.
• Metanephrine: 24 to 96 mcg/24 hrs or 0 to 300 mcg per gram creatinine.
• Normetanephrine: 75 to 375 mcg/24 hrs or 0 to 400 mcg per gram creatinine.

Elevated levels of the individual adrenomedullary hormones can indicate different conditions and/or causes, depending on which hormone or combination of hormones is elevated:

• Pheochromocytoma most commonly causes an increase in norepinephrine, metanephrines, and VMA although other catecholamines may also be increased. Measurement of 24-hour urinary metanephrines is considered the most sensitive test for this condition. When both metanephrines and VMA are used, the test approaches 100% in its clinical sensitivity. Neuroblastomas most frequently produce dopamine, norepinehprine, HVA, and VMA. HVA is the most specific marker since it is least likely to be increased in pheochromocytoma. The sensitivity with HVA alone is about 70%. The recommended initial tests for neuroblastoma includes both HVA and VMA to increase diagnostic sensitivity.
• Elevations of catecholamines and their metabolites are possible with, but do not directly confirm, thyroid disorders, low blood sugar (hypoglycemia), or heart disease.
• Electroshock therapy, or shock resulting from hemorrhage or exposure to toxins, can raise hormone levels.
• In the patient with normal or low baseline hormone levels, failure to show an increase in the sample taken after standing suggests an autonomic nervous system dys-function (the division of the nervous system responsible for the automatic or unconscious regulation of internal body functioning).
• In the absence of a tumor or other clinical findings, elevated adrenomedulary hormones may indicate prolonged stress or acute anxiety. They may also be elevated during serious physical illness.