At the start of the 24 hour period, the patient should void then discard the specimen. Then collect all urine including the final specimen voided at the end of the 24-hour collection period. Refrigerate urine during collection. Once the collection has ended, record the total volume, mix well, and send a 25 mL urine aliquot in a screw capped sterile cup. Total volume must be written on requisition or cup.

Preservative will be added to urine once it arrives at the lab. If storing the urine before sending, add 25 mL 6N HCL to the jug before storing.

Patient Preparation:
Medications that may interfere with metanephrine include amphetamines and amphetamine like compounds, appetite suppressants, bromocriptine, buspirone, caffeine, carbidopa – levopa (Sinemet), clonidine, dexamethasone, diuretics (in doses sufficient to deplete sodium), methyldopa (Aldomet), MAO inhibitors, nose drops, propafenone (Rythmol), trycyclic antidepressants, and vasodilators. Patient should consult their physician before discontinuing any medication.