Pheochromocytoma: a clinical review.

Few disorders of endocrine function are so sudden and dramatic in their presentation as those caused by a pheochromocytoma. This chromaffin cell tumor arises within the adrenal medulla or within the sympathetic nervous system and causes wide fluctuations in blood pressure, tachydysrhythmias, and manifestations of intense anxiety. The patient experiences explosive paroxysms of catecholamine overload.