gonadotropinsluteinizing

Luteinizing hormone, often abbreviated LH and sometimes referred to as lutropin, is a gonadotropin secreted by the anterior pituitary gland. It is one of the two main gonadotropins, the other being follicle-stimulating hormone (FSH), and it acts on the gonads to regulate reproductive function. LH participates in both male and female reproductive physiology and operates in concert with GnRH, the hypothalamic signal that drives its release in a pulsatile manner.

In females, LH plays a key role in the ovulatory process. A midcycle surge in LH triggers ovulation, the release of a mature oocyte from the ovarian follicle, and supports the formation and function of the corpus luteum. The corpus luteum then produces progesterone, which prepares the endometrium for potential implantation. LH also supports estrogen production by the ovaries and interacts with FSH to promote follicular development.

In males, LH stimulates Leydig cells in the testes to produce testosterone, which is essential for the development of male secondary sexual characteristics and for initiating and maintaining spermatogenesis. The action of LH on the gonads is tightly regulated by negative feedback from sex steroids.

Regulation and secretion of LH are governed by GnRH pulses from the hypothalamus. LH levels exhibit a circadian pattern and dramatic surges during the menstrual cycle in women, whereas in men the secretion is relatively steady with pulsatile fluctuations.

Clinically, LH measurements aid in diagnosing reproductive disorders and monitoring fertility treatments. Recombinant LH or LH agonists are used in assisted reproductive technologies to support follicular development or to induce ovulation, often in combination with FSH. LH deficiency and excess can be involved in conditions such as hypogonadism or polycystic ovary syndrome, respectively.