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Tests for equivocal cases of pheochromocytoma
What tests should be performed in equivocal cases of pheochromocytoma?
A number of pharmacologic tests can be performed but usually are not necessary.
Tests for Pheochromocytoma
TEST | RATIONALE |
---|---|
Regitine ® (phentolamine) test | Phentolamine is an alpha-blocker, and a reduction in blood pressure after its intravenous administration suggests a catecholamine excess. The test is neither sensitive nor specific |
Histamine test | This old test is seldom performed today because it is neither sensitive nor specific and can be dangerous |
Glucagon stimulation test | Glucagon stimulates catecholamine release and raises blood pressure and pulse rate in a patient with a pheochromocytoma. The risk of precipitating a hypertensive crisis can be blocked by prior administration of an alpha-adrenoceptor antagonist |
Clonidine suppression test | Clonidine decreases central sympathetic outflow in normal or nervous subjects, but does not suppress autonomous catecholamine production by a tumor. Failure to suppress plasma norepinephrine by more than 50%, and into the normal range, within 2–3 h after administration of an appropriate dose ( 0.2–0.3 mg ) of clonidine is highly suggestive of a pheochromocytoma |