Together with FSH (follicle stimulating hormone) LH belongs to the gonadotropins family. FSH and LH secretion is pulsatile and is controlled by the release of gonadotropin releasing hormone intermittent (GnRH) from the hypothalamus. LH and FSH regulates and stimulates the growth and function of the gonads (ovaries and testes).
The two hormones are produced by the gonadotrope cells of the anterior pituitary from where they reach the bloodstream and hence the gonads. At the ovaries level the gonadotropes stimulate the growth and maturation of follicles, corpus luteum formation and evolution, namely the synthesis and secretion of estrogen and progesterone. In men LH stimulates the testicular Leydig cells, so it is also called interstitial cell stimulating hormone.
The highest level of LH occurs in the middle of the menstrual cycle, inducing ovulation and corpus luteum formation (whose main secretion product is progesterone). In Leydig cells in the testes LH stimulates the production of testosterone and controls normal sperm maturation.
Recommendations for LH determination
For men: elucidation of hypothalamic-pituitary-gonadal axis dysfunction (mainly for differential diagnosis between primary testicular failure and testicular stimulation deficit), ectopic secretion of LH by a neoplasm.
In women: elucidating the hypothalamic-pituitary-gonadal axis dysfunction (mainly for differential diagnosis between primary ovarian insufficiency and deficiency of ovarian stimulation), polycystic ovarian disease (Stein-Leventhal syndrome), clarifying the causes of amenorrhea, congenital diseases with chromosome aberrations (eg, Turner syndrome), diagnosis and treatment of infertility, ectopic secretion of LH by a cancer, menopause syndrome.
Method – ELISA
Reference values - are dependent on age and sex:
In women, LH levels also vary with the menstrual cycle phases.