Includes Metanephrine, Normetanephrine, and Total Metanephrine
Patient Preparation Patient should avoid alcohol, coffee, tea, tobacco and strenuous exercise before collection. Overnight fasting is preferred. Patient should be relaxed in either a supine or upright position before blood is drawn.
Preferred Specimen(s) 2 mL plasma collected in a pre-chilled EDTA (lavender top) tube
Instructions The whole blood sample should be kept on wet ice until centrifuged (preferably at 4° C) to separate the plasma within 2 hours of venipuncture. After centrifugation, the plasma should be transferred to a plastic, leakproof vial and immediately frozen.
Transport Container Plastic screw-cap vial
Transport Temperature Frozen
Reject Criteria
- Heparinized plasma
- Serum
- CSF
- Room temperature urine
Methodology High Performance Liquid Chromatography (HPLC) • Electrochemical Detection
Clinical Significance Normetanephrine (NM) and metanephrine (MN) are the extra-neuronal catechol-o-methyl transferase (COMT) metabolites of the catecholamines; norepinephrine and epinephrine, respectively. Measurement of plasma metanephrines is more sensitive (but may be less specific) than measurement of catecholamines for the detection of pheochromocytoma. Proper interpretation of results requires awareness of recent medication/drug history (e.g., antihypertensive agents, alcohol, and cocaine) and other pre-analytical factors (e.g., stress, severe congestive heart failure, myocardial infarction) that influence release of catecholamines and metanephrines.