Hypocalcemic Activity of Serum in Patients with Medullary Carcinoma of the Thyroid

We have studied the hypocalcemic effect of serum from three patients with disseminated medullary carcinoma. Only one of three patients studied revealed significant hypocalcemic activity. The procedure we have described is simple to perform and, quite possibly, diagnostic when positive, but it is not sensitive enough to justify its use as a screening procedure in patients with suspected thyroid tumor. It might, however, be of interest and possible value in follow-up studies of patients with known medullary carcinoma, or in studies of the relatives of such patients. More sensitive methodology will be required for the consistent detection of this tumor and its hormonal by-products.