Comparison of the histamine and tyramine hydrochloride tests in the diagnosis of pheochromocytoma

Abstract

The tyramine hydrochloride test of Engelman and Sjoerdsma was compared with the standard cold pressor-histamine test in 7 patients with pheochromocytoma, 5 with essential hypertension, and 3 with labile hypertension. Urinary and blood catecholamines and urinary vanilmandelic acid (VMA) and metanephrines were also determined, One nontumor patient had a systolic pressor response (20 mm Hg greater than cold pressor response) after histamine; none had a response greater than 15 mm Hg after tyramine injection. The blood and urine values were normal in nontumor patients. Among the tumor patients, 5 had a marked pressor response to histamine, 5 had a mild pressor response (>20 mm Hg) to tyramine, and 6 had increased circulating pressor amine levels. All tumor patients had increased values for urinary metanephrines, 6 had increased catecholamine values, and 5 had increased VMA values.