Luteinizing Hormone: Meaning, Functions, Disorders & LH Test

Luteinizing hormones are called gonadotropic hormones, which are produced and released by a group of cells of the anterior pituitary gland. It is one of the main hormones that regulate the reproductive system by controlling the function of the female reproductive organs-the ovaries and the male reproductive organs-the testes.

Luteinizing Hormones

Hormones largely control the reproductive system of the human body and one such hormone is Luteinizing Hormone. The vital hormone is important for ensuring a healthy reproductive system, with different roles in the bodies of men and women. Luteinizing hormone is produced by the pituitary gland, binds with receptors in the hypothalamus before releasing into the bloodstream. Then it makes its way to the ovaries. Our body maintains LH levels in blood cells, but an increase in estrogen produces a spike in luteinizing hormone, which triggers ovulation-the release of a female egg cell from an ovary.

Luteinizing Hormone

In men, luteinizing hormone triggers the production and secretion of hormones called androgens from the testes and follicle-stimulating hormone(FSH), this hormone also controls spermatogenesis. For females, the ovaries are stimulated to produce estradiol by the hormone. An increase in luteinizing hormone lets the ovaries release an egg during ovulation within 2 weeks of a women’s cycle. If fertilization occurs, the luteinizing hormone will stimulate the luteum corpus which creates progesterone to help with pregnancy.

Functions of Luteinizing Hormone

Following are the functions of the luteinizing hormone:

• For ovulation in women, luteinizing hormone is responsible.
• It is responsible for the creation of sperm in men.
• LH stimulates testosterone creation from the interstitial cells of the testes.
• It plays an important role in the menstrual cycle.
• LH stimulates progesterone and estrogen production from the ovaries.
• This subsequently stimulates the corpus luteum to create progesterone.

Disorders of the Luteinizing Hormone

Here are the disorders that can be seen in the luteinizing hormone:

• High levels of LH in women can be a sign of primary ovarian failure.
• High levels of LH in men are a sign of testicular problems.
• Low levels of LH in women can be a sign of secondary ovarian failure.
• Low levels of LH results in disorder with the hypothalamus or pituitary gland.

Use of the Luteinizing Hormone Test

The LH test measures the amount of LH present in the blood. It is used to find any sexual abnormality or problems related to the pituitary gland.

• In females, these tests are often used to analyze the cause of irregular or stopped menstruation, infertility, to confirm the start of menopause or perimenopause in a woman who is about 50 years old, or to find out when ovulation occurs.
• In males, these tests are often used to analyze the cause for low sex drive, low sperm count, or infertility.
• In children, these tests are often used to analyze the cause for delayed or early puberty. In girls, puberty is considered early if it begins before the age of 8-9 years and is delayed if it does not begin until the age of 12-13 years. In boys, puberty is considered early if it begins before the age of 9-10 years and is delayed if it does not begin until the age of 13-14 years.

Risk factors and Hormones Levels

Hormonal Levels

Hormonal levels usually change with people’s age and gender. In women, LH levels change with the menstrual cycle and menopause. In men, hormonal levels usually change with age.

Normal values for LH blood levels in international units per liter (IU/L) are listed below:

• In women, the LH level changes at different stages of the menstrual cycle. It grows slowly during the follicular phase (1.68 to 15 IU/L). It reaches the peak in the middle of the cycle and triggers ovulation (21.9 to 56.6 IU/L) and then again decreases to a level of 0.61 to 16.3 UI/Lin in the luteal phase. After menopause, the normal range is 14.2 to 52.3 UI/L.
• In males, the normal range is 1.24 to 7.8 UI/L.

Risk Factor 

• The increased level of LH in women can directly affect the ovaries and a low level of LH in women can lead to secondary ovarian failure due to reduced secretion of other hormones from the pituitary gland. 
• The increased level of LH in men may show primary and secondary testicular failure and low levels of LH in adult men cause decreased sexual desire and sexual dysfunction due to low levels of testosterone. 
• For children, an increased level of LH can lead to early onset of puberty in children and a low level of LH in children causes delayed puberty and is a sign of hormone deficiency, ovarian or testicular failure, etc.

Things to Remember

• It is formed by the pituitary gland present underneath the brain under the direction of hypothalamus.
• Luteinizing hormones plays an essential part in sexual development and functioning.
• It helps in regulating the menstrual cycle in women.
• It stimulates the process of releasing an egg from the ovary.
• In men luteinizing hormones helps in the development of testosterone.