Luteinizing hormone (LH)
LH (luteinizing hormone), together with FSH (follicle stimulating hormone), belongs to the gonadotropin family. LH and FSH regulate and stimulate the growth and function of the gonads (ovaries and testes) synergistically.
Like FSH, TSH and hCG, LH is a glycoprotein consisting of two subunits (α‑ and β‑chains). This proteohormone, which consists of 121 amino acids 2 and three sugar chains, has a molecular weight of 29500 daltons.
In women, the gonadotropins act within the hypothalamus‑pituitary‑ovary regulating circuit to control the menstrual cycle. LH and FSH are released in pulses from the gonadotropic cells of the anterior pituitary and pass via the bloodstream to the ovaries. Here the gonadotropins stimulate the growth and maturation of the follicle and hence the biosynthesis of estrogens and progesterones. The highest LH‑concentrations occur during the mid‑cycle peak and induce ovulation and formation of the corpus luteum, the principal secretion product of which is progesterone. In the Leydig cells of the testes, LH stimulates the production of testosterone.
Determination of the LH concentration is used in the elucidation of dysfunctions within the hypothalamus‑pituitary‑gonads system.
The determination of LH in conjunction with FSH is utilized for the following indications: congenital diseases with chromosome aberrations (e.g. Turner's syndrome), polycystic ovaries (PCO), clarifying the causes of amenorrhea, menopausal syndrome, and suspected Leydig cell insufficiency.
SI units Conversion Calculator. Convert Luteinizing hormone (LH) level to mIU/mL, IU/L . Clinical laboratory units online conversion from conventional or traditional units to Si units. Table of conversion factors for Luteinizing hormone (LH) unit conversion to mIU/mL, IU/L .