Dexamethasone (2 mg q6h for 48 h) decreased serum T3 in normal and athyreotic subjects, and decreased T4 in normal subjects. Dexamethasone probably alters secretion and peripheral metabolism of thyroid hormones.

Anti-thyroglobulin antibodies, anti-thyroid microsomal antibodies, serum thyroglobulin, and carcinoembryonic antigen were assayed in sera of patients with a history of thyroid irradiation and in patients with thyroid cancer. In irradiated patients, the frequency of positive results for each test was increased above the frequency found in a control population, with a significant increase at P less than .05 for TGHA and TG levels. However, the tests (with the exception of serum thyroglobulin) did not clearly segregate irradiated patients with benign or malignant lesions from those with no clinically detectable abnormalities. Elevations of serum thyroglobulin above 300 ng/ml were found only in patients with thyroid cancer, but in these patients the diagnosis was usually clinically obvious.