Clinical Use: Screening test for presumptive diagnosis of catecholamine-secreting phaeochromocytomas or paragangliomas.[Note that 24h urine collection is still the sample of choice for diagnosing Pheochromocytoma. Plasma metadrenalines can be used if 24h urine collection pathologically difficult or if there is a strong clinical suspicion of Pheochromocytoma.]
Background: Pheochromocytoma is a rare, though potentially lethal, tumour of chromaffin cells of the adrenal medulla that produces episodes of hypertension with palpitations, severe headaches, and sweating (“spells”). Patients with Pheochromocytoma may also be asymptomatic and present with sustained hypertension or an incidentally discovered adrenal mass.Phaeochromocytomas and other tumours derived from neural crest cells (e.g. paragangliomas and neuroblastomas) secrete catecholamines (epinephrine, norepinephrine and dopamine). Metanephrines are the 3-methoxy metabolites of epinephrine and norepinephrine, respectively. The metanephrines are stable metabolites and are co-secreted directly with catecholamines by phaeochromocytomas and other neural crest tumours. This results in sustained elevations in plasma free metanephrine levels, making them more sensitive and specific than plasma catecholamines in the identification of Pheochromocytoma patients. Metanephrine and normetanephrine are both further metabolized to conjugated metanephrines and vanillylmandelic acid.
Reference Ranges: Normetanephrine: 120 – 1180 pmol/L
Metanephrine: 80 – 510 pmol/L
Associated Diseases:
Patient Preparation: None required
Specimen Requirements: Plasma (EDTA) sample required. Take on ice. Sample must be centrifuged, separated and the plasma frozen immediately upon receipt. Store sample frozen and dispatch frozen. Sample must be received by referral laboratory still frozen.
Turnaround Time: 1 week
Additional Information:
Referred Test: Referred test
Location: Freeman Hospital