Luteinising hormone

Fertility depends on a number of factors, with the functioning of the pituitary gland being the most essential of them. The pituitary gland produces hormones that influence fertility: luteinising hormone (luteus is Latin for yellow, LH) and follicle-stimulating hormone (FSH). The production of LH is regulated by hormones secreted by the ovaries, testicles, and hypothalamus.

The primary purpose of LH is to regulate the production of sex hormones and gametes in the ovaries in women and in the testicles in men.

In women, a rapid surge of LH triggers ovulation, or the release of an egg, once the follicle has developed. After ovulation, LH supports the function of the corpus luteum developing in place of the follicle and the secretion of progesterone. Progesterone prepares the lining of the uterus for pregnancy.

In men, luteinising hormone controls the Leydig cells that secrete testosterone.

When should LH be measured?

Measuring LH levels can help in investigating infertility, irregular menstrual periods, and pituitary gland disorders. In children, FSH and LH levels are examined for diagnosing delayed or early puberty and examining growth problems.

FSH and LH levels can also be measured to find out whether problems are caused by ovarian insufficiency or a disorder of the pituitary gland.

LH should be measured when the following symptoms are present:

• Disturbance of the menstrual cycle
• Night sweats
• Sleep disorders
• Mental disorder
• Loss of libido
• Vaginal dryness
• Infertility
• Determining the time of ovulation
• Testosterone deficiency in men (hypogonadism, a condition caused by diminished production of sex hormones)

What does the test measure?

The test indicates the level of LH in the blood. The test is often taken when examining the cause of infertility or examining the functioning of the pituitary gland.