The early diagnosis of medullary carcinoma of the thyroid gland in patients with multiple endocrine neoplasia type II.

Pentagastrin is a potent stimulator of thyrocalcitonin secretion from "C" cells. Since medulllary carcinoma of the thyroid gland (MCT) is a tumor composed of "C" cells, pentagastrin was used to screen a large kindred with multiple endocrine neoplasia type II (MCT, pheochromocytoma (s), and parathyroid hyperplasia). Four children with no thyroid abnormalities evident on physical examination, with negative thyroid scans, and with normal levels of plasma thyrocalcitonin both before and after calcium infusion, were found to have elevated peripheral levels of this hormone following pentagastrin injection. All four children were found to have very small foci of MCT, in both thyroid lobes at the time of total thyroidectomy. Pentagastrin stimulation used conjointly with selective catheterization of the inferior thyroid vein provided even greater diagnostic accuracy in detecting elevations in thyrocalcitonin secretion. This test has great diagnostic utility, especially in screening patients with multiple endocrine neoplasia type II.