A 29-year-old female who had undergone resection of an abdominal paraaortic
pheochromocytoma weighing 33 g at the age of 20 had had severe
headaches,
hypertension and
hyperhidrosis 3 years prior to the surgery. Postoperatively, her symptoms completely disappeared and urinary
catecholamines were normalized. She was well and had married and had had 2 children. She was admitted to our hospital on August 22, 1982, for further evaluation of
hypertension (154/100), which had been diagnosed 2 months previously. Endocrinological studies confirming the presence of a
pheochromocytoma were as follows: 1) Plasma
noradrenaline level was significantly elevated to 1750 pg/ml. 2) Urinary
catecholamine and their metabolites (Metanephrines and VMA) were markedly elevated. Her blood pressure was borderline
hypertension and its diurnal rhythm was lost. Her blood pressure decreased to normal values after the
oral administration of
labetalol (100 mg). Plasma
noradrenaline level was still high at 180 minutes after the
oral administration of
clonidine (150 micrograms). Hypertensive response to
insulin-induced
hypoglycemia (
regular insulin 0.1 u/kg i.v.) was observed, but blood pressure returned to normal after the infusion of
glucose alone. Hypertensive response to both
metoclopramide (5 mg i.v.) and
sulpiride (50 mg per os) was observed accompanying the significant elevation of plasma
noradrenaline. Computed tomography and ultrasonography revealed a
tumor localized between the aorta and the vena cava inferior. Selective venous sampling also revealed an intrathoracic
pheochromocytoma. On October 8, 1982, a 28 g mass was removed from the mediastinum just above the diaphragma. Histologically, it was typical of a
pheochromocytoma. Electron microscopy showed large polygonal cells with numerous large secretory granules characteristic of
noradrenaline-granules. Postoperative blood pressure was normal, but repeated measurements of plasma and urinary
catecholamines were still slightly high. We, therefore, followed her case carefully at our out-patient clinic. In order to clarify the mechanism of
catecholamine release by
metoclopramide and
sulpiride, tissue cultures of removed
pheochromocytoma with and without these drugs were carried out. The in vitro studies revealed that
metoclopramide released
noradrenaline eight-fold and
sulpiride 13-fold as compared with
noradrenaline in a control medium. We concluded that both drugs stimulated
catecholamine secretion directly from the
tumor and thus, careless administration of these drugs should be avoided when
pheochromocytoma was suspected, large or small. Finally, the rate of
tumor growth seemed to be very slow because it took 9 years to ach