Catecholamines, Fractionated, Urinary Free, 24-Hour Urine

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Category:

Turnaround Time: 4 - 7 days
CPT Code:

82384

Test Type: 30 mL aliquot Urine (24-hour)
Stability Time:

Temperature

Period

Room temperature

3 days

Refrigerated

14 days

Frozen

30 days at 70°C
Reference Range:

Adults:

• Epinephrine:

− 0 to 9 years: 0−11 μg/24 hours

− 10 to 19 years: 0−18 μg/24 hours

− >19 years: 0−20 μg/24 hours

• Norepinephrine:

− 0 to 9 years: 0−59 μg/24 hours

− 10 to 19 years: 0−90 μg/24 hours

− >19 years: 0−135 μg/24 hours

• Dopamine:

− 0 to 9 years: 0−414 μg/24 hours

− 10 to 19 years: 0−575 μg/24 hours

− >19 years: 0−510 μg/24 hours

Overview:

Work up neuroblastoma; diagnose pheochromocytoma. Pheochromocytomas and occasional paragangliomas may cause persistent or paroxysmal hypertension. Work up palpitation, severe headache, diaphoresis. Urine collections are preferred to blood sampling when there is suspicion for tumor (eg, family history of MEA II) when hypertension is not paroxysmal. Evaluate for possible multiple endocrine adenomatosis type II.

False-negatives and false-positives occur. Urine collections for metanephrines are among the best tests for pheochromocytoma.1 Sheps et al use urinary catecholamine fractionation as confirmation, following a metanephrine test.1 Neuroblastoma is better worked up with urinary collections for HVA and VMA. MHPG (3-methoxy-4-hydroxyphenylethylene glycol) is a major metabolite of norepinephrine in the central nervous system; it is a metabolite of some neuroblastomas.3

This test was developed and its performance characteristics determined by LabCorp. It has not been cleared or approved by the Food and Drug Administration.

The expression “free” in free catecholamine fractionation means unconjugated. This assay is of most value for pheochromocytoma when specimen is collected during a hypertensive episode. Since a 24-hour urine collection represents a longer sampling time than a random, or symptom-directed serum sample, and because catecholamine secretion by pheochromocytomas is intermittent, the urine test may detect some cases missed by a blood level.

1. Sheps SG, Jiang N-S, Klee GG, et al. Recent developments in the diagnosis and treatment of pheochromocytoma. Mayo Clin Proc. 1990; 65(1):88-95. PubMed 1967325

2. Landsberg L, Young JB. Pheochromocytoma. In: Braunwald E, Isselbacher KJ, Petersdorf RG, et al, eds. Harrison's Principles of Internal Medicine. New York, NY: McGraw-Hill Information Services Co;1987:1775-1778.

3. Knight JA, Wu JT. Catecholamines and their metabolites: Clinical and laboratory aspects. Lab Med. 1987; 18:153-158.

Collection Details:

Patient Preparation:

Avoid patient stress. Many drugs (reserpine and α-methyldopa, levodopa, monoamine oxidase inhibitors, and sympathomimetic amines) may interfere and should be discontinued two weeks prior to specimen collection. Nose drops, sinus and cough medicines, bronchodilators and appetite suppressants, α2-agonists, calcium channel blockers, converting enzyme inhibitors, bromocriptine, phenothiazine, tricyclic antidepressants, α- and β-blockers, and labetalol may interfere.1 Mandelamine® interferes, but thiazides do not. Caffeine products should be avoided before and during collection. The patient should not be subjected to hypoglycemia or exertion. Increased intracranial pressure and clonidine withdrawal can cause false-positive results.1,2

Collection Instructions:

Include 24-hour total urine volume on the test request form and date and time collection started and finished. Note: If original container is received with pH >3, but <5, adjust pH to <3 with 6N HCl.

Brown urine container with 30 mL 6N HCl preservative. Caution: Strong acid. May cause skin burns.

Instruct the patient to void at 8 AM and discard the specimen. Preservative must be added to the container prior to the start of collection. Then collect all urine including the final specimen voided at the end of the 24-hour collection period (ie, 8 AM the next morning). Label container. Keep collection on ice. Measure and record total urine volume on the test request form. Remove 20 mL aliquot. pH should be <5.

Refrigerate during and after collection.