Cushing's syndrome is a condition where both adrenal glands can overproduce the
                               hormone cortisol. Hypertension results from the interplay of several pathophysiological                                mechanisms regulating plasma volume, peripheral vascular resistance and cardiac output,                                all of which may be increased. More than 80% of patients with Cushing's syndrome have                                hypertension.                                In patients with pheochromocytoma increased secretion of catecholamines such as                                epinephrine and norepinephrine by a tumor (most often located in the adrenal medulla)                                causes excessive stimulation of adrenergic receptors, which results in peripheral                                vasoconstriction and cardiac stimulation. This diagnosis is confirmed by demonstrating                                increased urinary excretion of epinephrine and norepinephrine and/or their metabolites                                (vanillylmandelic acid). |