THE SERUM PATTERN OF THYROID HORMONES IN EUTHYROIDISM AND HYPERTHYROIDISM

The serum pattern of thyroid hormones in 26 euthyroid and 28 hyperthyroid subjects was studied by paper chromatographic techniques after the oral administration of radioactive iodine. Serum samples were drawn at intervals varying from one to 144 hours after the administration of radioiodine. Thyroxine was the major hormone demonstrated in every case. Triiodothyronine was detected in 3 of the 26 euthyroid subjects and in 10 of the 28 hyperthyroid patients. The presence of triiodothyronine in the serum did not seem to be associated with radiation effect on the thyroid gland nor could the existence of this hormone in the serum of the hyperthyroid subjects be correlated with any of the various parameters of thyroid function or the clinical severity of the thyrotoxicosis. No definite evidence of circulating monoiodotyrosine or diiodotyrosine was found, although in several cases an unidentified zone of labeled iodine was noted in the chromatograms at the DIT-MIT junction area. The acetic analogues of thyroxine and triiodothyronine and the compounds 3:3′-diiodothyronine and 3:3′:5′-triiodothyronine could not be detected in the serum of several euthyroid and hyperthyroid patients.