Methods for the Investigation of Thyroid Function

The commonly used laboratory investigations for the diagnosis and management of thyroid disorders are the thyroid hormones, thyroxine and triiodothyronine and the pituitary hormone, thyrotrophin (TSH). Simple, readily available radioimmunoassay methods for the measurement of the thyroid hormones and an immunochemiluminometric assay for TSH are described. Variations in total thyroid hormone levels owing to changes in thyroid hormone-binding proteins can be assessed by the measurement of free thyroxine. An equilibrium dialysis method is described. Methods for the measurement of TSH receptor antibodies and for thyroid peroxidase and thyroglobulin antibodies used in the assessment of autoimmune thyroid disease are given.