Gastrin Responses to a test meal in patients with familial medullary thyroid carcinoma

The serum gastrin response to a standard test meal was evaluated in patients with familial medullary thyroid carcinoma (MTC) and in normal subjects. Patients with MTC and elevated plasma calcitonin levels had a lower gastrin response to the test meal than did normal persons or MTC patients who had normal calcitonin levels postthyroidectomy. There was no significant difference between the mean gastrin response of the normal group and that of the MTC patients with normal calcitonin levels. The serum gastrin response was studied before and after thyroidectomy in four patients. In all four, the post-operative response was greater than the preoperative one . We conclude that patients with MTC may have reduced gastrin responses to a test meal. This effect may be related to circulating calcitonin, somatostatin, or other factors related to familial MTC.