Pheochromocytoma is a tumor of the adrenal gland. This tumor is typically benign (not cancerous) and can be cured by surgical removal. However, pheochromocytomas produce neurohormones called cateholamines (epinephrine and norepinephrine). High levels of catecholamines can result in high blood pressure, headaches, sweating, heart palpitations, nausea, vomiting, and other symptoms. These tumors are considered dangerous because of their unpredictable behavior. Patients with pheochromocytoma may experience blood pressures high enough to cause a stroke or heart attack in patients.

This study is designed to take patients suspected of having pheochromocytoma and confirm the diagnosis. This will be done using a variety of laboratory tests including a clonidine suppression test and glucagon stimulation test. These tests use drugs that can stimulate or reduce the activity of the tumor if it is present in the body.

Once a diagnosis is confirmed, patients participating in this study will undergo standard procedures to find the exact location of the tumor and receive standard therapy for the condition.