HUMORAL MARKERS FOR THYROID-CARCINOMA IN CLINICAL-PRACTICE

Serum thyroglobulin (TG) is a specific and sensitive marker for monitoring differentiated (papillary and follicular) thyroid cancer (DTC) and serum calcitonin (CT) for medullary thyroid cancer (MTC). Serum TG elevations cannot be used for the diagnosis of DTC but, after diagnosis and total thyroidectomy, are diagnostic of metastatic disease with very good agreement with the results of whole-body scan with iodine-131. Increased levels of serum TG are usually found also in patients with metastases which do not take up radioiodine. Since TG secretion is under thyrotropin control, caution must be used in the interpretation of serum TG results on thyroid suppressive therapy. In this condition, serum TG is usually lowered, particularly in the case of lymph node metastases. Contrary to TG, serum CT measurements are useful also for the diagnosis of MTC. This property is used to screen relatives of patients suspected of having the familial form of MTC. After treatment, serum CT is measured every 6 months for monitoring tumor recurrence or assessing the results of treatments