Evaluate presence of abnormal catecholamine production, may be elevated when VMA and catecholamines are within normal limits. Useful in the diagnosis of pheochromocytoma, neuroblastoma, ganglioneuroblastoma, and hypertension.
Metanephrines: 0-300 mcg/24 hrs, Normetanephrines: 50-800 mcg/24 hrs
- Fractionated Metanephrines, Urine
- Fractionation, Metanephrines and Normetanephrines
- Normetanephrines, Urine
- METANEPHRINE, URINE
Collect 24 hour urine specimen. Add 25 mL of 50% glacial acetic acid (15 mL for pediatric patients) to container prior to start of collection. Following collection, mix well, measure 24 hour urine volume, aliquot 20 mL into a plastic urine container and refrigerate. Record total 24 hour urine volume and collection dates/times on request form. Specimens with no preservative are also acceptable: add 50% glacial acetic acid to container following collection, mix well and send 20 mL aliquot (preferred); alternatively a non-acidified aliquot will be accepted. Patient must be off Aldomet (alpha methyldopa) and its derivatives for a period of not less than 5 weeks. This drug will falsely elevate the metanephrines and normetanephrines. A 12 hr overnight collection will be accepted, but reference ranges have been established only for 24 hr collections.
Coma, recent surgery, severe burns, and recent AMI will give falsely elevated values. There are no dietary restrictions BUT alcohol and nicotine in high doses and unusually high intake of coffee will acutely stimulate the adrenal medulla and may raise the metanephrines and normetanephrines to suspicious levels.