Pheochromocytoma: current perspectives in the pathogenesis, diagnosis, and management.

Pheochromocytomas (pheo) cause the most dramatic, life-threatening crises in all of endocrinology. A proper screening for pheo must be performed in any patient who has: 1) episodic headaches, tachycardia, and diaphoresis; 2) family history of pheo or multiple endocrine neoplasia; 3) incidental suprarenal mass; 4) paroxysms of tachyarrhythmias or hypertension; 5) adverse cardiovascular responses to anesthetic agents, histamine, phenothiazine, tricyclic antidepressants, etc); and 6) spells occurring during exercise, straining, etc. The key to diagnosing pheo is to suspect it, then to confirm it. Early recognition of its presence is critical to avoiding significant morbidity and mortality. Once suspected, the diagnosis can be confirmed with biochemical testing in virtually all patients. The combination of resting plasma catecholamines > or =2000 pg/mL and urinary metanephrines > or =1.8 mg/24 h has a diagnostic accuracy of 98% in both sporadic and hereditary pheos. When available, measurement of plasma free metanephrines should be performed especially in hereditary pheos. Provocative (glucagon) and suppression tests (clonidine) may be necessary when baseline measurements are inconclusive. CT and MRI are equally sensitive for localization (98% and 100%, respectively), but have lower specificities (70% and 67%). MIBG is 100% specific, but less sensitive (78%). The availability of various medical (selective alpha-1- and beta-adrenergic receptor antagonists, calcium channel blockers) and surgical modalities have made successful management more promising than ever before.