Diagnostic applications of calcitonin immunoassay.

The radioimmunoassay for calcitonin has become an important clinical pro­ cedure for the diagnosis of medullary thyroid carcinoma. Most patients with this thyroid tumor have elevated basal levels of the hormone which can establish the presence of the malignancy. In some patients, provocative tests of calcitonin secretion are necessary for definitive diagnosis. In addition to establishing the diagnosis, the calcitonin assay can be used to define the extent of the disease and to evaluate therapeutic procedures. This assay may also be useful in the diagnosis of other calcitonin-producing tumors.