Q: My family doctor thinks that my high blood pressure is due to a pheochromocytoma and has arranged for me to see another doctor to have tests done. What is a pheochromocytoma, and what is involved in the tests?
A: A pheochromocytoma is a tumor that can cause high blood pressure by releasing excessive amounts of two hormones, epinephrine (adrenalin) and norepinephrine. The production of these hormones, together called catecholamines, can be constant or intermittent, thereby resulting in either sustained or periodic hypertension.
Episodes of hypertension, resulting from surges of hormone release, may be accompanied by severe headaches, rapid heart rate, sweating, flushing, chest pain, dizziness when standing (orthostatic hypotension), nausea and agitation. Although the tumor is most often found in the central portion (medulla) of the adrenal gland, pheochromocytomas can be located at a number of other sites, usually in the back of the abdomen.
Ten percent of pheochromocytomas are present in both adrenals, but the tumor is malignant in only 5 percent to 10 percent of patients. Some patients inherit pheochromocytomas in association with benign tumors (adenomas) of the parathyroid gland and malignant tumors of the thyroid (medullary thyroid carcinomas) as part of a familial syndrome known as multiple endocrine neoplasia.
The diagnosis of pheochromocytoma is made by detecting excessive levels of catecholamines in the blood or high levels of either catecholamines or their metabolic breakdown products in a 24-hour urine collection. Other tests, such as a blood calcium, may be done if a parathyroid adenoma is suspected. The site of the pheochromocytoma can generally be identified by a CT scan or by magnetic resonance imaging (MRI).
In most cases, the hypertension is cured by surgical removal of the tumor after a period of controlling the blood pressure by administering drugs that block the actions of both epinephrine and norepinephrine.
Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine.