[The sympathetic system and neuroendocrine hypertension]

Sporadic pheochromocytoma is a rare tumor that should be taken into account in patients with hypertensive crisis, arrhythmias, and panic disorder. Familial pheochromocytoma is frequently found in subjects with von Hippel-Lindau disease, multiple endocrine neoplasia type II, neurofibromatosis, and SDHD gene mutations. The prevalence of sporadic pheochromocytoma is very low, approximately 0.05% among subjects with essential hypertension and even less in the general population. However, aggressive diagnostic intervention is recommended whenever a pheochromocytoma is suspected because the uncontrolled catecholamine release from the tumor can lead to serious and potentially lethal complications. Plasma free metanephrines have been shown to have high sensitivity and specificity in the biochemical diagnosis of sporadic and familial pheochromocytoma. Measurement of 24-hour urinary fractionated metanephrines may be an acceptable alternative in many patients. The current approach to the diagnostic localization of pheochromocytoma relies on computed tomography (CT), magnetic resonance imaging (MRI) and [123-I] and [131-I] MIBG scintigraphy. CT and MRI have very high sensitivity but low specificity, whereas MIBG scintigraphy has good specificity but its sensitivity is less than optimal, especially for the detection of metastases. In difficult cases, PET imaging appears to be promising.