Further Evaluation of the Tyramine Test for Pheochromocytoma

Abstract

Nineteen (73 per cent) of 26 patients with pheochromocytoma had positive responses to pharmacologic testing with tyramine whereas only three (3 per cent) of 88 patients with other forms of hypertension had false-positive responses. False-negative responses were more frequent among patients with the familial variety of pheochromocytoma associated with medullary carcinoma of the thyroid gland and in patients receiving hydrochlorothiazide or phenoxybenzamine. The inhibitory effect of these drugs lasted up to four days and two weeks, respectively, after their discontinuation. Except for palpitation, there were no untoward effects from the tyramine tests.