Luteinizing Hormone (LH) is a glycoprotein secreted by the anterior pituitary. It is composed of two dissimilar subunits. The alpha chain is identical to that of FSH, and very similar to TSH and HCG. The beta chain differs considerably from FSH and TSH, but again is similar to HCG.
LH and FSH are members of the gonadotropin family. They regulate and stimulate the growth and function of the gonads (ovaries and testes) synergistically. In women, within a control system involving the hypothalamus, anterior pituitary and the ovaries, LH and FSH, are responsible for the cyclical ovarian changes during the menstrual cycle.
LH and FSH are released from the gonadotrophic cells of the Anterior Pituitary into the blood stream. They act upon the ovaries to stimulate the growth and maturation of the follicle. The mid cycle surge induces ovulation and formation of the corpus luteum, the principal secretion product of which is progesterone. Progesterone controls LH secretion via a negative feedback system.
At menopause, ovarian function ceases, leading to high levels of LH due to the removal of the negative feedback mechanisms. In males, LH promotes testosterone production by the Leydig cells, and along with FSH, maintains spermatogenesis.
Pituitary dysfunction can result in low levels of LH and cause infertility. The functional state of the pituitary can be determined dynamically after the administration of LH-RH (LH-RH Stimulation test).
Determination of LH is useful for investigating dysfunction of the Hypothalamus – Pituitary – Gonads system. e.g Turner’s syndrome, polycystic ovaries, Amenorrhea, Menopausal syndrome and Leydig cell insufficiency.
Males: 1.3 – 8.0mIU/mL
Follicular: 3.3 – 11.3 mIU/mL
Ovulatory: 17.8 – 111mUI/mL
Luteal: 1.1 – 13.4mIU/mL
- Three patient identifiers from
- N.H.S. number
- Unit Number