New tests for thyroid function

The secretion of thyroid hormones is regulated by the pituitary polypeptide hormone, thyrotrophin, also known as the thyroid-stimulating hormone (TSH). Recently several companies have marketed highly sensitive immunoradiometric TSH assays to allow distinction between euthyroidism and hyperthyroidism. These assays utilitse labelled antibodies instead of the labelled antigen employed in conventional RIA, and have detection limits varying from 0.04 to 0,2 μU/ml. An approach to thyroid function testing using this sensitive TSH assay is presented