Gonadotropiinit

Gonadotropins are a group of glycoprotein hormones that stimulate the gonads. In humans the principal gonadotropins are follicle-stimulating hormone (FSH) and luteinizing hormone (LH), produced by the anterior pituitary. A placental gonadotropin, human chorionic gonadotropin (hCG), mimics LH activity and supports early pregnancy. In Finnish, the plural form is gonadotropiinit.

Their release is controlled by gonadotropin-releasing hormone (GnRH) from the hypothalamus in a pulsatile manner; this pulsatility is essential for normal gonadal function. Continuous exposure to high levels suppresses responsiveness.

Molecularly, FSH and LH are heterodimeric glycoproteins sharing a common alpha subunit but having distinct beta subunits that determine receptor binding; a similar arrangement applies to hCG. Glycosylation yields different isoforms and influences half-life.

In clinical use, gonadotropins are used to induce follicular development and ovulation in assisted reproduction, to stimulate spermatogenesis in men with hypogonadotropic hypogonadism, and in certain cases of hypogonadism. Preparations include recombinant FSH, recombinant LH, and human menopausal gonadotropin (hMG) containing FSH and LH activity; hCG is used to trigger ovulation or to maintain luteal function.

Risks include ovarian hyperstimulation syndrome (OHSS), multiple gestations, vascular events, or adverse reactions to injections. Dosing and timing are individualized and closely monitored by ultrasound and hormone assays.