Pentagastrin stimulation of calcitonin in pheochromocytoma does not always indicate multiple endocrine neoplasia type II.

The diagnosis of pheochromocytoma in a 48-year-old man was confirmed by elevated catecholamine secretion and a left adrenal mass on computerized tomography. Because of a plausible family history for Multiple Endocrine Neoplasia Type II, a calcitonin level was determined which was elevated, and pentagastrin stimulation caused a 235% increase. These findings normalized following surgical removal of the single adrenal tumor. It is concluded that pentagastrin stimulation of calcitonin is not necessarily diagnostic of medullary thyroid carcinoma, and such a response in a patient presenting with pheochromocytoma may not indicate underlying Multiple Endocrine Neoplasia Type II.