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Editor's Correspondence
November 22, 1999

Hyperresponsiveness of Arginine Vasopressin to Metoclopramide in Patients With Pheochromocytoma

Arch Intern Med. 1999;159(21):-. doi:

The administration of metoclopramide hydrochloride is commonly used as a provocative test in the screening of patients with pheochromocytoma because it produces a severe pressor reaction in these patients.1 This phenomenon has been attributed to catecholamine-releasing effects of the antidopaminergic agent.1 However, a dissociation between blood pressure (BP) and plasma catecholamines has occurred in patients with pheochromocytoma,2 suggesting that other endocrine factors may play a role in the control of BP in these patients. Specifically, the pressor response during stimulation with metoclopramide might be mediated at least in part by enhanced circulating levels of vasopressin; the stimulatory effect of metoclopramide on vasopressin secretion is well known.3 To verify this possibility, we have evaluated the arginine vasopressin (AVP) secretory pattern in 3 patients affected by pheochromocytoma during stimulation with metoclopramide.