entire thyroid gland is removed at an early age, before there is spread of the tumor. The parathyroid tumors and pheochromocytomas are removed when they cause clinical symptomatology. Hereditary medullary thyroid carcinoma or multiple endocrine neoplasia (MEN2) accounts for approximately 25% of all medullary thyroid carcinomas. Seventy-five percent of medullary thyroid carcinoma occurs in individuals without an identifiable family history and is assigned the term "sporadic". Individuals who develop sporadic medullary thyroid carcinoma tend to be older and have more extensive disease at the time of initial presentation than those with a family history (screening is likely to be initiated at an early age in the hereditary form). Approximately 25-60% of sporadic medullary thyroid carcinomas have a somatic mutation (one that occurs within a single "parafollicular" cell) of the RET proto-oncogene. This mutation is presumed to be the initiating event, although there could be other as yet unidentified causes. Markers While the increased serum concentration of calcitonin is not harmful, it is useful as a marker which can be tested in blood. A second marker, carcinoembryonic antigen (CEA), also produced by medullary thyroid carcinoma, is released into the blood and it is useful as a serum or blood tumor marker. In general, measurement of serum CEA is less sensitive than serum calcitonin for detecting the presence of a tumor, but has less minute to minute variability and is therefore useful as an indicator of tumor mass. Diagnosis Diagnosis is primarily performed via fine needle aspiration of the lesion of the thyroid to distinguish it from other types of thyroid lesions. Microscopic examination will show an amyloid stroma with hyperplasia of parafollicular cells. A recent Cochrane rystematic review assessed the diagnostic accuracy of basal and stimulated calcitonin for Medullary Thyroid Carcinoma. Although both basal and combined basal and stimulated calcitonin testing presented high accuracy (sensitivity: between 82% and 100%; specificity: between 97.2% and 100%), these results had a high risk of bias due to design flaws of included studies. Overall, the value of routine testing of calcitonin for diagnosis and prognosis of Medullary Thyroid Carcinoma remains uncertain and questionable. Treatment Surgery and radiation therapy have been the major treatments for medullary thyroid carcinoma. A plasma level of metanephrines should be checked before surgical thyroidectomy takes place to evaluate for the presence of pheochromocytoma since 25% of people found to have medullary thyroid cancer have the inherited form from the MEN2A syndrome.