[Screening for the familial form of medullary cancer of the thyroid].

Several questions concerning the diagnosis of medullary carcinoma of the thyroid (MCT) arise from two studies of kindred of a patient with MCT carried out in 1977 and 1983. Diagnosis is based on calcitonin level determination after stimulation by pentagastrine. This method should be proposed for all kindred every time a positive diagnosis of MCT has been made for the first time in a given family. When calcitonin levels are normal it is necessary to repeat this test once a year in all individuals over 5 years of age with a high risk of MCT. Surgical removal should be proposed in cases where calcitonin levels are high. But in practice, this may be difficult and screening must be adapted to each individual case.