Pheochromocytoma is a tumor. It is made up of special adrenal gland cells. The cells secrete hormones such as epinephrine and norepinephrine. These hormones help to regulate the heart rate and blood pressure. The cells may secrete excessive amounts of the hormones. This results in periods of:

Most of these tumors are benign and grow on the adrenal glands, which are located on top of the kidneys. Other tumors occur elsewhere in the body.

Adrenal Glands
Nucleus factsheet image
Copyright © Nucleus Medical Media, Inc.

In most cases, pheochromocytoma has no known cause. In others, it is caused by a genetic mutation.