Sporadic medullary thyroid carcinoma (MTC) usually presents as a single nodule (SNT), a presentation common to other thyroid tumors. The establishment of its frequency in SNT has diagnostic and therapeutic implications, since surgery for MTC differs from other tumors. Serum calcitonin (CT), the standard marker for MTC, were measured in 60 cases of SNT (55 females, 22-75 years of age). Fine needle aspiration biopsy (FNAB) of the nodules was also performed, being 100% specific and 67% sensitive for detecting thyroid carcinomas. Sixty percent of clinically suspected malignancies were confirmed post-surgically. MTC was diagnosed by serum CT in 1 of 59 cases (1.69%), confirmed by FNAB and submitted to appropriate surgery. It accounted for 12.5% of thyroid malignancies of this group, since 6 papillary and 1 undifferentiated cases were also diagnosed. Therefore, routine serum CT measurement in SNT is a strong tool in the diagnosis and adequate surgery of MTC. Both IRMA and RIA were useful in this screening. The latter, however, can detect MTC earlier, due to its ability to measure non-monomeric forms of CT, abundant in this condition.
Thyroid; Calcitonin; Uninodular goiter; Medullary thyroid carcinoma
