tirotropin

Tirotropin, also known as thyrotropin, is a glycoprotein hormone produced by the anterior pituitary gland. It stimulates the thyroid gland to synthesize and release the thyroid hormones thyroxine (T4) and triiodothyronine (T3).

TSH acts by binding to the TSH receptor on thyroid follicular cells, activating the cAMP signaling pathway. This promotes iodide uptake, stimulation of thyroid peroxidase, synthesis of thyroglobulin, and ultimately the production and secretion of T4 and T3. TSH also supports growth and maintenance of the thyroid gland.

TSH secretion is regulated by hypothalamic thyrotropin-releasing hormone (TRH) and by negative feedback from circulating free T4 and T3. The thyroid axis operates as a dynamic system to maintain circulating thyroid hormone levels within narrow limits.

Clinically, serum TSH is a central marker of thyroid function and is typically measured to evaluate suspected hypo- or hyperthyroidism and to monitor thyroid hormone therapy. In thyroid cancer management, recombinant human thyrotropin (rhTSH) may be used to stimulate radioactive iodine uptake or to facilitate diagnostic imaging without inducing hypothyroidism.

Common adverse effects of rhTSH are generally mild and transient; as with any parenteral hormone, reactions at the injection site, headaches, or hypersensitivity are possible. Cautions include pituitary or hypothalamic disorders, pregnancy considerations, and active malignancy status, which influence its use.