Pheochromocytomas are tumors in the adrenal gland that produce an excess of catecholamines (adrenalin). About half the patients with this condition have sustained sustained elevations in blood pressure and half have intermittent elevations in blood pressure. In patients with intermittent hypertension symptoms vary from once every month to multiple times/day and the "attacks" last anywhere between 30 seconds to 1 week. Patients with pheochromocytomas usually come to the doctor because of their symptoms. The presence of three symptoms: headaches, increased sweating and palpitations was a strong indicator of possible pheochromocytomas. Physicians frequently refer to the "Rules of Ten" when talking about pheochromocytomas: 10% are cancerous, 10% are in both adrenals rather than in only one adrenal gland, 10% are outside the adrenal gland, 10% are more common in certain families and 10% occur in children. In the case of malignant tumors up to, 30-40% of these may be located outside of the adrenal gland.

Of all the adrenal causes of high blood pressure, pheochromocytoma appears to be the least common, accounting for less than 0.3% of the cases of hypertension. The prevalence seems to be equally distributed among the age groups accounting for 3% of the cases of secondary hypertension both in patients between 18-49 years of age and those 50 and older and equally distributed between men and women. The diagnosis of pheochromocytoma is usually considered in patients with intermittent hypertension with the clinical symptoms of headaches (present in 35% of patients), increased perspiration (present in 34% of patients) and palpitations (present in 22% of patients) but this diagnosis is frequently missed. Although with the of widespread use of imaging techniques such as abdominal MRI or CT scans, the number of clinically unsuspected pheochromocytomas has dropped.

Testing for pheochromocytoma may involve a 24 hour urine collection or a blood test. Mild elevations in catecholamines are usually from other causes besides pheochromocytomas. The finding of 1.5-2 fold higher than the upper limit of normal of catecholamines is highly suggestive of pheochromocytomas. Pheochromocytomas tend to be large (about 5 cm). Nuclear medicine studies may also helpful, in particular use of meta-iodobenzylguanidine (MIBG), which is taken up by the tumor. The treatment for pheochromocytomas is surgical removal, which is performed laparascopically.