The Metanephrines, Fractionated, Free, LC/MS/MS, Plasm test contains 1 test with 3 biomarkers.
Metanephrines, Fractionated, Free, LC/MS/MS, Plasma
Patient Preparation: Patient should avoid alcohol, coffee, tea, tobacco and strenuous exercise prior to collection. Overnight fasting is preferred. Patients should be relaxed in either a supine or upright position before blood is drawn.
Limitations: False-positive results have been observed in patients with either chronic kidney disease or hypertension.
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., antyhypertensive agents, alcohol, cocaine) and other pre-analytical factors (e.g., stress, severe congestive heart failure, myocardial infarction) that influence release of catecholamines and metanephrines.