Thyrogen injection Thyrogen contains Thyrotropin Alfa, a recombinant human thyroid-stimulating hormone (rhTSH) synthesized using recombinant DNA technology. It binds to thyroid-stimulating hormone (TSH) receptors on thyroid epithelial cells, stimulating iodine uptake and organification, as well as the synthesis and release of thyroglobulin (Tg), triiodothyronine (T3), and thyroxine (T4). It is indicated for use as an adjunctive diagnostic tool for serum thyroglobulin (Tg) testing, with or without radioiodine imaging, in the follow-up of well-differentiated thyroid cancer patients, and as an adjunctive therapy for radioiodine ablation of thyroid tissue remnants in post-thyroidectomy patients.