Familial medullary thyroid carcinoma.

Medullary thyroid carcinoma (M.C.T.) is a tumour of the calcitonin-secreting cells of the thyroid gland; it affects both lobes, has a variable malignant potential, and is often familial. Despite the availability of diagnostic plasma-calcitonin immunoassays, the condition is rarely considered in the initial assessment of a patient with a thyroid mass so that the is often disseminated by the time it is diagnosed, inadequate surgery is performed, and family members are not investigated. We studied 22 members of a family with M.C.T. and gave alcohol to provoke calcitonin secretion. 3 (excluding the index case) had raised basal calcitonin levels and the diagnosis of M.C.T. was confirmed at operation; their calcitonin levels became undetectable after total thyroidectomy. 3 others had detectable levels after alcohol stimulation and are being re-screened at regular intervals.