Catecholamines, Blood and Urine

Synonym/acronym: Epinephrine, norepinephrine, dopamine.

Common use

To assist in diagnosing catecholamine-secreting tumors, such as those found in the adrenal medulla, and in the investigation of hypertension. The urine test is used to assist in diagnosing pheochromocytoma and as a work-up of neuroblastoma.

Specimen

Plasma (2 mL) collected in green-top (heparin) tube. Urine (25 mL) from a timed specimen collected in a clean, plastic, amber collection container with 6N hydrochloric acid as a preservative.

Normal findings

(Method: High-performance liquid chromatography)

Blood	Conventional Units	SI Units
(Conventional Units × 5.46)
Epinephrine
Newborn–1 yr	0–34 pg/mL	0–186 pmol/L
1–18 yr	0–80 pg/mL	0–437 pmol/L
Adult
Supine, 30 min	0–110 pg/mL	0–600 pmol/L
Standing, 30 min	0–140 pg/mL	0–764 pmol/L
(Conventional Units × 5.91)
Norepinephrine
Newborn–1 yr	0–659 pg/mL	0–3,895 pmol/L
1–18 yr	0–611 pg/mL	0–3,611 pmol/L
Adult
Supine, 30 min	70–750 pg/mL	414–4,432 pmol/L
Standing, 30 min	200–1,700 pg/mL	1,182–10,047 pmol/L
(Conventional Units × 6.53)
Dopamine
Newborn–1 yr	0–42 pg/mL	0–274 pmol/L
1–18 yr	0–32 pg/mL	0–209 pmol/L
Adult
Supine or standing	0–48 pg/mL	0–313 pmol/L

Urine	Conventional Units	SI Units
(Conventional Units × 5.46)
Epinephrine
Newborn–9 yr	0–11 mcg/24 hr	0–60 nmol/24 hr
10–19 yr	0–18 mcg/24 hr	0–98 nmol/24 hr
20 yr–older adult	0–20 mcg/24 hr	0–109 nmol/24 hr
(Conventional Units × 5.91)
Norepinephrine
Newborn–9 yr	0–59 mcg/24 hr	0–349 nmol/24 hr
10–19 yr	0–90 mcg/24 hr	0–532 nmol/24 hr
20 yr–older adult	0–135 mcg/24 hr	0–798 nmol/24 hr
(Conventional Units × 6.53)
Dopamine
Newborn–9 yr	0–414 mcg/24 hr	0–2,703 nmol/24 hr
10–19 yr	0–575 mcg/24 hr	0–3,755 nmol/24 hr
20 yr–older adult	0–510 mcg/24 hr	0–3,330 nmol/24 hr

Description

Catecholamines are produced by the chromaffin tissue of the adrenal medulla. They also are found in sympathetic nerve endings and in the brain. The major catecholamines are epinephrine, norepinephrine, and dopamine. They prepare the body for the fight-or-flight stress response, help regulate metabolism, and are excreted from the body by the kidneys. Levels are affected by diurnal variations, fluctuating in response to stress, postural changes, diet, smoking, drugs, and temperature changes. As a result, blood measurement is not as reliable as a 24-hr timed urine test. For test results to be valid, all of the previously mentioned environmental variables must be controlled when the test is performed. Results of blood specimens are most reliable when the specimen is collected during a hypertensive episode. Catecholamines are measured when there is high suspicion of pheochromocytoma but urine results are normal or borderline. Use of a clonidine suppression test with measurement of plasma catecholamines may be requested. Failure to suppress production of catecholamines after administration of clonidine supports the diagnosis of pheochromocytoma. Elevated homovanillic acid levels rule out pheochromocytoma because this tumor primarily secretes epinephrine. Elevated catecholamines without hypertension suggest neuroblastoma or ganglioneuroma. Findings should be compared with metanephrines and vanillylmandelic acid, which are the metabolites of epinephrine and norepinephrine. Findings should also be compared with homovanillic acid, which is the product of dopamine metabolism.

This procedure is contraindicated for

N/A

Indications

Assist in the diagnosis of neuroblastoma, ganglioneuroma, or dysautonomia
Assist in the diagnosis of pheochromocytoma
Evaluate acute hypertensive episode
Evaluate hypertension of unknown origin
Screen for pheochromocytoma among family members with an autosomal dominant inheritance pattern for Lindau–von Hippel disease or multiple endocrine neoplasia

Potential diagnosis

Increased in

Diabetic acidosis (epinephrine and norepinephrine) (related to metabolic stress; are released to initiate glycogenolysis, gluconeogenesis, and lipolysis)
Ganglioblastoma (epinephrine, slight increase; norepinephrine, large increase) (related to production by the tumor)
Ganglioneuroma (all are increased; norepinephrine, largest increase) (related to production by the tumor)
Hypothyroidism (epinephrine and norepinephrine) (possibly related to interactions among the immune, endocrine, and nervous systems)
Long-term manic-depressive disorders (epinephrine and norepinephrine) (some studies indicate a relationship between decreased catecholamine levels and manic depressive illnesses; the pathophysiology is not well understood)
Myocardial infarction (epinephrine and norepinephrine) (related to physical stress)
Neuroblastoma (all are increased; norepinephrine and dopamine, largest increase) (related to production by the tumor)
Pheochromocytoma (epinephrine, continuous or intermittent increase; norepinephrine, slight increase) (related to production by the tumor)
Shock (epinephrine and norepinephrine) (related to physical stress)
Strenuous exercise (epinephrine and norepinephrine) (related to physical stress)

Decreased in

(related to inability of sympathetic nervous system to activate postganglionic neuron)

(some studies indicate a relationship between decreased catecholamine levels and Parkinson’s disease; the pathophysiology is not well understood)

Critical findings

N/A

Interfering factors

Drugs that may increase plasma catecholamine levels include ajmaline, chlorpromazine, cyclopropane, diazoxide, ether, monoamine oxidase inhibitors, nitroglycerin, pentazocine, perphenazine, phenothiazine, promethazine, and theophylline.
Drugs that may decrease plasma catecholamine levels include captopril, and reserpine.
Drugs that may increase urine catecholamine levels include atenolol, isoproterenol, methyldopa, niacin, nitroglycerin, prochlorperazine, rauwolfia, reserpine, syrosingopine, and theophylline.
Drugs that may decrease urine catecholamine levels include bretylium tosylate, clonidine, decaborane, guanethidine, guanfacine, methyldopa, ouabain, radiographic substances, and reserpine.
Stress, hypoglycemia, smoking, and drugs can produce elevated catecholamines.
Secretion of catecholamines exhibits diurnal variation, with the lowest levels occurring at night.
Secretion of catecholamines varies during the menstrual cycle, with higher levels excreted during the luteal phase and lowest levels during ovulation.
Diets high in amines (e.g., bananas, avocados, beer, aged cheese, chocolate, cocoa, coffee, fava beans, grains, tea, vanilla, walnuts, Chianti wine) can produce elevated catecholamine levels.
Failure to collect all urine and store 24-hr specimen properly will yield a falsely low result.
Failure to follow dietary restrictions before the procedure may cause the procedure to be canceled or repeated.

Nursing Implications and Procedure

Pretest

Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
Patient Teaching: Inform the patient this test can assist in the diagnosis of a type of tumor that produces excessive amounts of hormones related to physical and emotional stress.
Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
Obtain a history of the patient’s endocrine system, as well as results of previously performed laboratory tests and diagnostic and surgical procedures.
Record the date of the patient’s last menstrual period.
Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
Review the procedure with the patient.

Blood

Inform the patient that he or she may be asked to keep warm and to rest for 45 to 60 min before the test. Inform the patient that multiple specimens may be required. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain that there may be some discomfort during the venipuncture. Inform the patient that a saline lock may be inserted before the test because the stress of repeated venipunctures may increase catecholamine levels.

Urine

Provide a nonmetallic urinal, bedpan, or toilet-mounted collection device. Address concerns about pain related to the procedure. Explain to the patient that there should be no discomfort during the procedure. Usually a 24-hr time frame for urine collection is ordered. Inform the patient that all urine over a 24-hr period must be saved; if a preservative has been added to the container, instruct the patient not to discard the preservative. Instruct the patient not to void directly into the laboratory collection container. Instruct the patient to avoid defecating in the collection device and to keep toilet tissue out of the collection device to prevent contamination of the specimen. Place a sign in the bathroom as a reminder to save all urine. Instruct the patient to void all urine into the collection device, then pour the urine into the laboratory collection container. Alternatively, the specimen can be left in the collection device for a health-care staff member to add to the laboratory collection container.

Blood and Urine

Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
Instruct the patient to follow a normal-sodium diet for 3 days before testing, abstain from smoking tobacco for 24 hr before testing, and avoid consumption of foods high in amines for 48 hr before testing.
Instruct the patient to avoid self-prescribed medications for 2 wk before testing (especially appetite suppressants and cold and allergy medications, such as nose drops, cough suppressants, and bronchodilators).
Instruct the patient to withhold prescribed medication (especially methyldopa, epinephrine, levodopa, and methenamine mandelate) if directed by the health-care provider (HCP).
Instruct the patient to withhold food and fluids for 10 to 12 hr before the test. Protocols may vary from facility to facility.
Instruct the patient collecting a 24-hr urine specimen to avoid excessive stress and exercise during the test collection period.
Prior to blood specimen collection, prepare an ice slurry in a cup or plastic bag to have ready for immediate transport of the specimen to the laboratory. Prechill the collection tube in the ice slurry.

Intratest

Potential complications: N/A
Ensure that the patient has complied with dietary, medication, and activity restrictions and with pretesting preparations; ensure that food and fluids have been restricted for at least 10 to 12 hr prior to the procedure, and that excessive exercise and stress have been avoided prior to the procedure. Instruct the patient to continue to avoid excessive exercise and stress during the 24-hr collection of urine.
Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
Instruct the patient to cooperate fully and to follow directions.
Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection. Perform a venipuncture as appropriate.

Blood

Perform a venipuncture between 6 and 8 a.m.; collect the specimen in a prechilled tube.
Remove the needle and apply direct pressure with dry gauze to stop bleeding. Observe/assess venipuncture site for bleeding or hematoma formation and secure gauze with adhesive bandage.
Ask the patient to stand for 10 min, and then perform a second venipuncture and obtain a sample as previously described.
Each sample should be placed in an ice slurry immediately after collection. Information on the specimen labels should be protected from water in the ice slurry by first placing the specimens in a protective plastic bag. Promptly transport the specimens to the laboratory for processing and analysis.

Urine

Obtain a clean 3-L urine specimen container, toilet-mounted collection device, and plastic bag (for transport of the specimen container). The specimen must be refrigerated or kept on ice throughout the collection period. If an indwelling urinary catheter is in place, the drainage bag must be kept on ice.
Begin the test between 6 and 8 a.m. if possible. Collect first voiding and discard. Record the time the specimen was discarded as the beginning of the timed collection period. The next morning, ask the patient to void at the same time the collection was started and add this last voiding to the container.
If an indwelling catheter is in place, replace the tubing and container system at the start of the collection time. Keep the container system on ice during the collection period or empty the urine into a larger container periodically during the collection period; monitor to ensure continued drainage, and conclude the test the next morning at the same hour the collection was begun.
At the conclusion of the test, compare the quantity of urine with the urinary output record for the collection; if the specimen contains less than what was recorded as output, some urine may have been discarded, invalidating the test.

Blood and Urine

Include on the collection container’s label the amount of urine, test start and stop times, and ingestion of any foods or medications that can affect test results.
Promptly transport the specimen to the laboratory for processing and analysis.

Post-Test

Inform the patient that a report of the results will be made available to the requesting HCP, who will discuss the results with the patient.
Instruct the patient to resume usual diet, fluids, medications, and activity, as directed by the HCP.
Recognize anxiety related to test results. Discuss the implications of abnormal test results on the patient’s lifestyle. Provide teaching and information regarding the clinical implications of the test results, as appropriate.
Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

Related Monographs

Related tests include angiography adrenal, calcitonin, CT renal, HVA, metanephrines, renin, and VMA.
Refer to the Endocrine System table at the end of the book for related tests by body system.