Causes

Researchers don't know exactly what causes a pheochromocytoma. The tumor develops in specialized cells, called chromaffin cells, located in the center of an adrenal gland. These cells release certain hormones, primarily adrenaline (epinephrine) and noradrenaline (norepinephrine), that help control many body functions, such as heart rate, blood pressure and blood sugar.

The role of hormones

Adrenaline and noradrenaline trigger your body's fight-or-flight response to a perceived threat. The hormones cause your blood pressure to increase and your heart to beat faster. They prepare other body systems that enable you to react quickly. A pheochromocytoma causes more of these hormones to be released and causes them to be released when you're not in a threatening situation.

Related tumors

While most of the chromaffin cells are located in the adrenal glands, small clusters of these cells are also in the heart, head, neck, bladder, back wall of the abdomen and along the spine. Chromaffin cell tumors, called paragangliomas, may result in the same effects on the body.