Hypertension associated with pheochromocytoma Positive regitine blocking test UMLS:C4025594 Regitine produces an alpha-adrenergic block of relatively short duration. In the regitine blocking test, regitine is injected rapidly and blood pressure is recorded immediately after injection, at 30-second intervals for the first 3 minutes, and at 60-second intervals for the next 7 minutes. A positive response to the reginitine blocking test is present when the blood pressure is reduced more than 35 mmHg systolic and 25 mmHg diastolic. A typical positive response is a reduction in pressure of 60 mmHg systolic and 25 mmHg diastolic. A positive response is suggestive of pheochromocytoma and should generally be confirmed by other diagnostic procedures such as measurement of urinary catecholamines or their metabolites. HP:0003574 A positive response to the regitine blocking test consisting of a substantial reduction in blood pressure following administration of regitine, indicative of the presence of increased levels of epinephrine and norepinephrine in the circulation, which is seen in pheochromocytoma-associated hypertension.