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Test ID CATU Catecholamine Fractionation, Free, 24 Hour, Urine

Reporting Name

Catecholamine Fract, Free, U

Useful For

An auxiliary test to fractionated plasma and urine metanephrine measurements in the diagnosis of pheochromocytoma and paraganglioma

 

An auxiliary test to urine vanillylmandelic acid and homovanillic acid determination in the diagnosis and follow-up of patients with neuroblastoma and related tumors

Specimen Type

Urine


Advisory Information


This assay is of greatest value when the specimen is collected during a hypertensive episode.

 

Unless the purpose of the measurement is drug monitoring, discontinue any epinephrine, norepinephrine, or dopamine injections or infusions for at least 12 hours before specimen draw.

 

Do not perform the test on patients withdrawing from legal or illegal drugs known to cause rebound catecholamine release during withdrawal (see Cautions for details)



Necessary Information


24-Hour volume is required.



Specimen Required


Patient Preparation: Discontinue drugs that release or hinder metabolism of epinephrine, norepinephrine, or dopamine for at least 1 week before obtaining the specimen (see Cautions for details). If this is not possible for medical reasons, contact the laboratory to discuss whether a shorter drug-withdrawal period may be acceptable.

Supplies: Plastic, 10-mL urine tube (T068)

Specimen Volume: 2 mL

Collection Instructions:

1. Collect urine for 24 hours.

2. Add 25 mL of 50% acetic acid as preservative at start of collection. Use 15 mL of 50% acetic acid for children less than 5 years old. This preservative is intended to achieve a pH of between approximately 2 and 4.

Additional Information: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens in Special Instructions for multiple collections.


Specimen Minimum Volume

1.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Urine Refrigerated (preferred) 7 days
  Frozen  14 days
  Ambient  7 days

Reference Values

NOREPINEPHRINE

 <1 year: <11 mcg/24 hours

1 year: 1-17 mcg/24 hours

2-3 years: 4-29 mcg/24 hours

4-6 years: 8-45 mcg/24 hours

7-9 years: 13-65 mcg/24 hours

≥10 years: 15-80 mcg/24 hours

 

EPINEPHRINE

 <1 year: <2.6 mcg/24 hours

1 year: <3.6 mcg/24 hours

2-3 years: <6.1 mcg/24 hours

4-9 years: 0.2-10.0 mcg/24 hours

10-15 years: 0.5-20.0 mcg/24 hours

≥16 years: <21 mcg/24 hours

 

DOPAMINE

<1 year: <86 mcg/24 hours

1 year: 10-140 mcg/24 hours

2-3 years: 40-260 mcg/24 hours

≥4 years: 65-400 mcg/24 hours

 

For SI unit Reference Values, see https://www.mayomedicallaboratories.com/order-tests/si-unit-conversion.html.

Day(s) and Time(s) Performed

Monday through Saturday; 8 a.m.

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

82384

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CATU Catecholamine Fract, Free, U In Process

 

Result ID Test Result Name Result LOINC Value
TM48 Collection Duration 13362-9
VL46 Urine Volume 3167-4
2106 Norepinephrine 2668-2
2107 Epinephrine 2232-7
2108 Dopamine 2218-6

Clinical Information

The catecholamines (dopamine, epinephrine, and norepinephrine) are derived from tyrosine via a series of enzymatic conversions. All 3 catecholamines are important neurotransmitters in the central nervous system and play crucial roles in the autonomic regulation of many homeostatic functions, namely, vascular tone, intestinal and bronchial smooth muscle tone, cardiac rate and contractility, and glucose metabolism. Their actions are mediated via alpha and beta adrenergic receptors and dopamine receptors, all existing in several subforms. The 3 catecholamines overlap but also differ in their receptor activation profile and consequent biological actions.

 

The systemically circulating fraction of the catecholamines is derived almost exclusively from the adrenal medulla, with small contributions from sympathetic ganglia. They are normally present in the plasma in minute amounts, but levels can increase dramatically and rapidly in response to change in posture, environmental temperature, physical and emotional stress, hypovolemia, blood loss, hypotension, hypoglycemia, and exercise.

 

In patients with pheochromocytoma, a potentially curable tumor of catecholamine producing cells of the adrenal medulla, or less commonly of sympathetic ganglia (paraganglioma), urine catecholamine levels may be elevated. This results in episodic or sustained hypertension and often in intermittent attacks of palpitations, cardiac arrhythmias, headache, sweating, pallor, anxiety, tremor, and nausea ("spells"). Elevations of the urine levels of 1 or several of the catecholamines also may be observed in patients with neuroblastoma and related tumors (ganglioneuroblastomas and ganglioneuromas) and, very occasionally, in other neuroectodermal tumors.

 

At the other end of the spectrum, inherited and acquired syndromes of autonomic dysfunction/failure and autonomic neuropathies are characterized by either inadequate production of 1 or several of the catecholamines, or by insufficient release of catecholamines upon appropriate physiological stimuli (eg, change in posture from supine to standing, cold exposure, exercise, stress).

Interpretation

Diagnosis of Pheochromocytoma:

This test should not be used as the first-line test for pheochromocytoma. PMET / Metanephrines, Fractionated, Free, Plasma (the most sensitive assay) and/or METAF / Metanephrines, Fractionated, 24 Hour, Urine (almost as sensitive and highly specific) are the recommended first-line laboratory tests for pheochromocytoma.

 

However, urine catecholamine measurements can still be useful in patients whose plasma metanephrines or urine metanephrines measurements do not completely exclude the diagnosis. In such cases, urine catecholamine specimens have an 86% diagnostic sensitivity when cut-offs of >80 mg/24 hour for norepinephrine and >20 mg/24 hour for epinephrine are employed. Unfortunately, the specificity of these cut-off levels for separating tumor patients from other patients with similar symptoms is only 88%. When more specific (98%) decision levels of >170 mg/24 hours for norepinephrine or >35 mg/24 hours for epinephrine are used, the assay’s sensitivity falls to about 77%.

 

Diagnosis of Neuroblastoma:

Vanillylmandelic acid, homovanillic acid, and sometimes urine catecholamine measurements on spot urine or 24-hour urine are the mainstay of biochemical diagnosis and follow-up of neuroblastoma; 1 or more of these tests may be elevated.

Clinical Reference

1. Young WF Jr: Pheochromocytoma and primary aldosteronism. In Endocrine Neoplasms. Edited by A Arnold. Boston. Kluwer Academic Publishers, 1997, pp 239-261

2. Hernandez FC, Sanchez M, Alvarez A, et al: A five-year report on experience in the detection of pheochromocytoma. Ann Intern Med 2000;33:649-655

3. Pacak K, Linehan WM, Eisenhofer G, et al: Recent advances in genetics, diagnosis, localization, and treatment of pheochromocytoma. Ann Intern Med 2001;134:315-329

4. Alexander F: Neuroblastoma. Urol Clin North Am 2000;27:383-392

5. McDougall AJ, McLeod JG: Autonomic neuropathy, I. Clinical features, investigation, pathophysiology, and treatment. J Neurol Sci 1996;137:79-88

6. Lenders JW, Pacak K, Walther MM, et al: Biochemical diagnosis of pheochromocytoma: which test is best? JAMA 2002;287:1427-1434

Analytic Time

2 days (not reported on Sundays)

Method Name

High-Performance Liquid Chromatography (HPLC)
Includes unconjugated epinephrine, norepinephrine, and dopamine

Urine Preservative Collection Options

Ambient

No

Refrigerated

Yes

Frozen

Yes

6N HCl

Yes

50% Acetic Acid

Preferred

Na2CO3

No

Toluene

No

6N HNO3

Yes

Boric Acid

Yes

Thymol

No

 

Forms

If not ordering electronically, complete, print, and send an Oncology Test Request Form (T729) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/oncology-request-form.pdf)