Table 7: Pheochromocytoma: Screening and diagnosis *

Biochemical screening tests for pheochromocytomas:

1. To screen for pheochromocytomas, 24 h urinary total metanephrines (sensitivity 95%) and urinary metanephrine-to-creatinine ratio (sensitivity 100%) should be assessed. Plasma catecholamines and, where available, plasma metanephrines may also be considered if clinical suspicion is high, particularly during a hypertensive episode or for those with familial forms. Urinary or plasma VMA measurements should not be used as screening tests.  In a low risk setting, plasma fractionated free metanephrine measurements can be used to rule out pheochromocytoma.
2. In the presence of borderline biochemical test results (e.g., plasma noradrenaline and adrenaline levels of approximately 500ng/L to 2000 ng/L) or potentially false positive results, repeated testing and/or the clonidine suppression test may be used.

* Reprinted with permission of CHEP