Correlation between calcitonin and carcinoembryonic antigen levels in medullary carcinoma of the thyroid.

We have detected high values of carcinoembryonic antigen in the blood of patients suffering from medullary carcinoma of the thyroid (MCT). Levels of the antigen and calcitonin, the hormone which is specifically secreted by these tumours, are positively correlated. Stimulation of calcitonin secretion has no effect on carcinoembryonic antigen levels. Though the antigen assay is non specific for MCT, it may improve the diagnosis and follow-up of MCT-patients.