Metanephrines

Test ID:

706791

CPT code:

83835

Clinical Use:

Evaluate the presence of abnormal catecholamine production, may be elevated when VMA and catecholamines are within normal limits; diagnose pheochromocytoma, neuroblastoma, and ganglioneuroblastoma

Test Information:

Metanephrine and normetanephrine are metabolic products of epinephrine and norepinephrine, the adrenal medullary hormones secreted by pheochromocytomas. Because secretion is usually episodic, plasma catecholamine, drawn during an asymptomatic period may be normal, while total metanephrines collected over 24 hours would be abnormal. On the other hand, a tumor could be intermittently active, but secrete over a full 24-hour period total metanephrines within normal limits.

Metanephrine has been positive in 98% to 99%, VMA in about 90% of patients with pheochromocytoma. A Mayo Clinic group advocates use of metanephrines as an initial test with confirmation by assay of urine catecholamine fractions.

Specimen Type:

Urine (24-hour)

Requested Volume:

10 mL aliquot

Minimum Volume:

2.5 mL aliquot

Container Type:

Plastic urine container with no preservative or 6N HCl

Patient Preparation:

No caffeine before or during collection. Monamine oxidase inhibitors should be discontinued at least one week prior to beginning collection.

Collection:

Instruct the patient to void at 8 AM and discard the specimen. Then collect all urine including the final specimen voided at the end of the 24-hour collection period (ie, 8 AM the next morning). Screw the lid on securely. Label container with patient’s name, date and time collection started, and date and time collection finished. Measure and record total 24-hour volume. Mix well; send aliquot. (HCl is an acceptable preservative if required for a concurrently collected assay.)