HETEROGENEITY OF CIRCULATING CALCITONIN LEVELS - RELATIONS WITH CALCITONIN BIOSYNTHESIS IN MEDULLARY-THYROID CARCINOMAS

Calcitonin (CT), a hypocalcemic and hypophosphatemic hormone, is produ ced by the C-cells of the thyroid gland. It is the main tumoral marker of medullary thyroid carcinoma (MTC). Hypersecretion of CT is also as sociated with other types of tumors. Thus, heterogeneity of ciculating CT can play an important role in the accurate determination of hormon e levels in blood samples obtained from MTC patients. Further studies will be necessary to establish the predictive value of the several pep tides coded by the calcitonin gene family. All of them specifically re flect the ways and the pattern of alternative splicing of the primary transcript of the Calc I gene. Such relations implicate further invest igations concerning the relationship between calcitonin circulating le vels, biosynthetic activity of C-cells and the expression of gene enco ding for this hormone, in normal and neoplastic conditions.