Catecholamines, Fractionated, Urinary Free, 24-Hour Urine
Also known as: Dopamine, 24-Hour Urine, Epinephrine, 24-Hour Urine, Fractionation, Urinary Free Catecholamines, Free Catecholamine Fractionation, Norepinephrine, 24-Hour Urine
Use
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.
Special Instructions
Include the 24-hour total urine volume on the test request form and date and time collection started and finished. Notably, if the original container is received with a pH >3 but <5, it should be adjusted to <3 with 6N HCl.
Limitations
False-negatives and false-positives can occur. Urine collections for metanephrines are among the best tests for pheochromocytoma. Neuroblastoma is better evaluated with urinary collections for HVA and VMA. MHPG (3-methoxy-4-hydroxyphenylethylene glycol) is a major metabolite of norepinephrine in the central nervous system and is a metabolite of some neuroblastomas. The assay may not accurately detect pheochromocytomas unless the specimen is collected during a hypertensive episode.
Methodology
Mass Spectrometry
Biomarkers
LOINC Codes
- 92938-0
- 11046-0
- 2232-7
- 2667-4
- 2668-2
- 2217-8
- 2218-6
Result Turnaround Time
4-7 days
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
30 mL aliquot
Minimum Volume
4 mL aliquot (Note: This volume does not allow for repeat testing.)
Container
Brown urine container with 30 mL 6N HCl preservative. Caution: Strong acid. May cause skin burns.
Collection Instructions
Instruct the patient to void at 8 a.m. 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 (i.e., 8 a.m. the next morning). Label container. Keep collection on ice. Measure and record the total urine volume on the test request form. Remove 20 mL aliquot. pH should be <5.
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. 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.
Storage Instructions
Refrigerate during and after collection.
Causes for Rejection
Specimen with no preservative; original container with pH >5
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 3 days |
| Refrigerated | 14 days |
| Frozen | 30 days at -70°C |