[Familial studies in medullary thyroid carcinoma and multiple endocrine adenomatosis]

Medullary thyroid carcinoma secreting calcitonin frequently occurs familially and in association with pheochromocytomas and hyperplastic parathyroid glands (multiple endocrine adenomatosis type II). Thyroid tumors develop from a hyperplasia of the C-cells and can be diagnosed at an early stage in the light of raised plasma levels of calcitonin and with provocation tests using i.v. calcium. Observation of two index patients with pheochromocytomas and one patient with medullary thyroid carcinoma led to endocrinological study of three families. A one min i.v. calcium injection test has been shown to be a reliable and well tolerated screening procedure for the medullary carcinoma. Endocrine adenomatosis type II was diagnosed in two of the three kindreds. While pheochromocytomas were usually found in only 30-50% of the affected family members, an elevated plasma adrenalin level after histamine provocation was measured in all our patients with pathological calcitonin tests. The third family did not present evidence of adrenal hyperplasia. Plasma levels of calcitonin were only marginally stimulated after the i.v. administration of calcium, and the stimulation remained constant for over seven years; therefore, either familial medullary thyroid carcinoma could not be diagnosed with certainty or the condition remained clinically stable.