A 12-year-old boy presented to the hospital with exertional dyspnea, resting tachycardia (heart rate, 180 beats/min), and hypertension (blood pressure, 220/110 mm Hg). Investigations showed a left para-aortic pheochromocytoma, and the patient was scheduled for surgical resection of the tumor.

Intraoperative manipulation of the tumor lead to hypertension; however, systolic blood pressure never exceeded 220 mm Hg, and heart rate never exceeded 100 beats/min because of treatment with a calcium-channel blocker and a ß₁-adrenergic blocker. Plasma concentrations of catecholamine did not vary markedly, but the plasma level of arginine vasopressin did: The level was 220 pmol/L (normal, 0.4 to 4.0 pmol/L) during surgical manipulation and 26 pmol/L immediately after tumor resection (Table 1). Postoperative cytologic analysis confirmed a well-differentiated pheochromocytoma.

Immediately after resection, some tumor tissue was dissected into small pieces for measurement of the secretion rates of various hormones. In the absence of an exogenous secretagogue, arginine vasopressin was spontaneously secreted at a mean rate of 1.8 fmol/mL of perifusion eluate. The rate of arginine vasopressin secretion was increased 8000-fold during a corticotropin-releasing factor pulse and returned to baseline after the end of stimulation.

This is the first report of a human pheochromocytoma that secreted vasopressin. The intraoperative increase in the plasma level of arginine vasopressin and the moderate increase in adrenocorticotropin hormone level (Table 1) exclude the possibility that the release of arginine vasopressin was of pituitary origin. Moreover, secretion of arginine vasopressin from the pheochromocytoma was 2 times the basal secretion and 400 times the increase in corticotropin-releasing factor-stimulated release obtained from the normal medulla gland [1].

A high rate of arginine vasopressin secretion during surgical resection of pheochromocytoma may contribute to pheochromocytoma-induced hypertension [2], and hemodynamic changes induced by laparoscopic removal [3] have been related to vasopressin-induced vasoconstriction [4].