[Analysis of circulating calcitonin for the detection of familial and sporadic medullary cancer].

Medullary carcinoma of the thyroid is always linked to a high basal level of calcitonin or to an abnormal increase of the hormone after stimulation: this is generally the case in incipient tumoral metastases and in sub-clinical familial cases. Moreover, a normal stimulation test does not allow to eliminate the probability of a tumoral heredity and it is often difficult to discriminate between sporadic and familial cases or normal and high risk subjects during familial screening. So, in the absence of established rules of follow-up, repetitive stimulation tests will be often necessary as well as an extensive investigation of members of the families.