Thyroid-Stimulating Hormone

Thyroid stimulating hormone (TSH), or thyrotropin, is a glycoprotein synthesized and secreted by the pituitary gland. It stimulates synthesis and secretion of the thyroid hormones, thyroxine (T4) and triiodothyronine (T3). Secretion of TSH is stimulated by thyrotropin-releasing hormone (TRH), a hypothalamic tripeptide. TSH synthesis and release are regulated via a negative feedback mechanism by the level of thyroid hormones. Increased serum levels of free T4 and T3 depress TSH secretion (hyperthyroidism), while decreased serum levels of free T4 and T3 result in excess TSH secretion (primary hypothyroidism). Serum TSH concentration is inversely proportional to the free T4 (FT4) concentration in a log/linear relationship, making TSH a sensitive marker for monitoring thyroid hormone replacement therapy. Swiss-Prot Accession Number: Alpha P01215; Beta P01222.

Swiss-Prot Accession Number: P01215, P01222