Thyrocalcitonin Activity in Metastatic Medullary Thyroid Carcinoma

The distinctive histologic entity, medullary (solid) carcinoma of the thyroid,¹has attracted much attention lately because of the diverse endocrinologic syndromes with which it may be associated. Several authors have pointed out the coincidental finding of bilateral pheochromocytoma,²,³parathyroid adenoma,⁴the carcinoid syndrome,⁵Cushing's syndrome,⁶and diabetes mellitus³in patients with medullary carcinoma of the thyroid or in their immediate relatives or in both. However, the full endocrine potential of this neoplasm is only now becoming clear with the recent observations that the tumor tissue itself may be the site of elaboration of various humoral substances, namely, serotonin,⁷prostaglandins,⁸and thyrocalcitonin.⁹ Thyrocalcitonin (calcitonin) activity in the human thyroid gland was demonstrated by Aliapoulios et al,¹⁰and subsequent evidence¹¹,¹²indicated that the parafollicular cell may be the site of its production. Because the histologic features of medullary carcinoma of the