Objective： To investigate the changes of calcitonin （CT） and calcitonin gene-related peptide （CGRP） in patients with medullary thyroid carcinoma （MTC）. Methods： Fifty-eight cases of MTC were selected and the relationship between the CT levels and metastasis was investigated. The immunohistochemical method was used to detect the expression of CT and CGRP in the 58 samples of MTC tissues. The CT and CGRP in 30 newly diagnosed MTC inpatients were measured before operation and in the first few days after operation using a radioimmunoassy. Results： （1） The rate of residual tumor had a significant difference between the normal serum CT group one month after operation and the elevated group at the same period （P〈0.01）. （2） Immunohistochemical study revealed the positive rate of CT was about 98%, and that of the CGRP was 87.8%. （3） Part of the patients had an elevated CGRP levels while CT levels was normal. （4） The serum CT levels were decreased to a stable range one week after operation. Conclusion： CT is a useful index to evaluate the efficacy of surgical treatment. The measurement of serum CGRP is helpful in the diagnosis of MTC, especially for those whose preoperative CT levels are normal.
