Clonidine-Suppression Test — A Useful Aid in the Diagnosis of Pheochromocytoma

THE diagnosis of pheochromocytoma is considered secure when typical signs and symptoms (e.g., hypertension, sweating, palpitation, and headaches) are associated with unequivocal biochemical evidence of excessive catecholamine production. However, excluding the diagnosis in the 5 to 10 per cent of patients with essential hypertension who have suggestive symptoms and borderline increases in plasma catecholamines or urinary catecholamine metabolites or both remains a common problem. In such patients, the basic approach is pharmacologic. Pharmacologic agents are administered either to provoke the release of a catecholamine or to block its action. The resulting changes in indexes of catecholamine release or blood pressure . . .