Screening test for presumptive diagnosis of catecholamine-secreting pheochromocytomas or paragangliomas.Pheochromocytoma is a rare, though potentially lethal, tumor 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. Pheochromocytomas and other tumors derived from neural crest cells (eg, paragangliomas and neuroblastomas) secrete catecholamines (epinephrine, norepinephrine, and dopamine). Total urine metanephrines 1300 mcg/24 hours and lower can be detected in nonpheochromocytoma hypertensive patients.