Serum Thyrotropin and the Assessment of Thyroid Status

Excerpt

Since their relatively recent introduction into clinical practice, sensitive immunoassays for serum thyrotropin have enhanced the ability of clinicians to firmly establish diagnoses which were once difficult or impossible to confirm with conventional thyrotropin assays. Despite the excellent ability of the latter to identify patients with primary hypothyroidism, their ability to differentiate euthyroid from hyperthyroid patients was limited because of assay insensitivity. Immunometric assays for thyrotropin differ from the conventional radioimmunoassay; rather than labeling the antigen component of the antigen-antibody complex, two separate monoclonal antibodies, each directed at a different epitope of the thyrotropin molecule, are used. This two-site or