Analysis index

3 ml EDTA-plasma, separate plasma as quickly as possible (Stability in plasma at 4°C – 8°C: 2 days). In case of longer storage or shipping time, plasma needs to be frozen.

The determination of metanephrine and normetanephrine in plasma can be used for the screening of pheochromocytomas/paragangliomas. To avoid false-positive results, blood extraction should be via a previously placed intravenous catheter in an empty-stomached patient after 20 – 30 min rest in supine position. With the uniform use of frozen EDTA-plasma, glutathione tubes are no longer required.

Refrain from coffee, tea, nicotine, alcohol, chocolate, bananas, eggs and nuts for 2 – 3 days prior to the test. As far as tenable, all medication should be discontinued 7 – 14 days before the test: Theophylline, MAO-inhibitors, phenothiazine, methyldopa and levodopa can be responsible for an increased catecholamine excretion for up to two weeks and should definitely be discontinued. Diuretics, alpha- and beta-receptor blockers, vasodilators, calcium antagonists, angiotensin-II antagonists and ACE inhibitors and Clonidine (Catapressan®) should be discontinued, where possible. A strong symphathicus stimulation caused by hypoglycemia, physical exertion or an increased intracranial pressure, may also lead to an increased catecholamine excretion.

Metanephrine: < 90 ng/l

Normetanephrine: < 200 ng/l

Suspicion of secondary hypertension, diagnosis and monitoring of pheochromocytoma or pheochromocytoma-paraganglioma syndrome, screening of MEN 2A, neurofibromatosis type 1, Hippel-Lindau syndrome and incidentalomas, neuroblastomas (in connection with vanillic- and homovanillylmandelic acid) and ganglioneuroma.

As pheochromocytomas and paragangliomas often only secrete catecholamines periodically (whereby paragangliomas cannot produce adrenalin nor metanephrine), multiple testing is recommended, especially during or after hypertensive crisis or palpitations. It should be noted, that there are also non-secreting pheochromocytomas; those however tend to be more common in older people.