What is Luteinizing hormone?
Luteinising hormones are called gonadotropic hormones, which are produced and released by the group of cells of the anterior pituitary gland. It is one of the main hormones that control the reproductive system by controlling the function of female reproductive organs – ovaries and male reproductive organs – testes.
LH is formed in the pituitary gland, binds with receptors in the hypothalamus before it is released into the bloodstream. It then makes its way to the ovaries. Our body maintains the level of LH in the blood cells, but an increase in estrogen creates a spike in luteinizing hormone, which triggers ovulation – the release of a female egg cell from an ovary.
Also Read: Hormones
In males, the luteinizing hormone triggers the production and secretion of hormones known as androgens from testes. Along with the secretion of androgens and Follicle Stimulating Hormone (FSH), this hormone also controls spermatogenesis.
In females, the luteinizing hormone causes ovulation of the Graafian follicles and also maintains the corpus luteum, which is developed from the traces of the Graafian follicles after the ovulation process that produces progesterone.
Also Read: Difference between Estrogen and Progesterone
Functions of Luteinizing hormone
- It is responsible for ovulation in females.
- It plays a crucial role in the menstrual cycle.
- It is responsible for the production of sperm in males.
- LH stimulates estrogen and progesterone production from the ovary.
- It subsequently stimulates the corpus luteum to produce progesterone.
- LH stimulates testosterone production from the interstitial cells of the testes.
Disorders of the Luteinizing hormone
- High levels of LH in a woman may be a sign of primary ovarian failure.
- Low levels of LH in a woman may be a sign of secondary ovarian failure.
- High levels of LH in men are a sign of a problem with the testicles.
- Low levels of LH results in disorder with the pituitary gland or hypothalamus.
What is LH test used for?
The Luteinizing hormone test, also called the LH test is a type of a blood test, which is performed to check the functioning of both luteinizing hormone and follicle-stimulating hormone (FSH), which controls the sexual functions in both male and female.
This test is also used in different ways, depending on whether an individual is a woman, a man, or a child.
In women, these tests are most often used to diagnosis the:
- Causes of infertility
- Find out when ovulation occurs.
- Causes for irregular or stopped menstrual periods.
- To confirm the start of menopause, or perimenopause in a woman around 50 years old.
In men, these tests are most often used to diagnosis the:
- Causes of infertility.
- Causes for low sex drive.
- Causes for a low sperm count.
In children, these tests are most often used to diagnosis the:
- Causes for early or delayed puberty.
- In girls, puberty is considered early if it starts before the age of 8 – 9 and delayed if it has not started by the age of 12 – 13.
- In boys, puberty is considered early if it starts before the age of 9 – 10 and delayed if it has not started by the age of 13 – 14.
Hormones Levels and the Risk Factors
The hormonal level usually varies with the age and sex of an individual. In women, the LH levels vary with the menstrual cycle and menopause. In men, the hormonal level usually varies with age.
Listed below are the normal values of LH blood levels measured in international units per litre (IU/L):
- During the follicular phase of the menstrual cycle: 1.9 to 12.5 IU/L.
- During the peak of the menstrual cycle: 8.7 to 76.3 IU/L.
- During the luteal phase of the menstrual cycle: 0.5 to 16.9 IU/L.
- A pregnant woman: less than 1.5 IU/L.
- At menopause: 15.9 to 54.0 IU/L.
- During the period of using contraceptives: 0.7 to 5.6 IU/L.
- Men between the ages of 20 and 70: 0.7 to 7.9 IU/L.
- Men over 70: 3.1 to 34.0 IU/L.
The increased levels of both LH and FSH cause primary ovarian failure.
Low levels of both LH and FSH cause a secondary ovarian failure. This also results in the reduced production and secretion of hormones from the pituitary gland, which is called the master gland.
The increased levels of LH can show primary and secondary testicular failure.
Low levels of LH in adult males may lead to the reduced production of testosterone levels, which results in sexual dysfunction and lack of sexual interest.
The increased levels of LH can cause early puberty in children, which is called precocious puberty.
The decreased levels of LH in children cause delayed puberty and indicates certain ovarian or testicular failure, hormone deficiency, etc.
Also Read: Hormones and Hormonal Disorders
This article concludes the introduction to the Luteinizing hormone (LH), their level of production and functions.
Frequently Asked Questions on Luteinizing hormone
What are normal LH levels by age?
The normal LH levels vary with sex and age. The normal levels of Luteinizing hormone (LH) in women vary during menopause, pregnancy and post-menopause.
In men, the LH levels between the ages of 20 to 70 are – 0.7 to 7.9 IU/L
What does LH do in the female reproductive system?
In the female reproductive system, the Luteinizing hormone functions by:
- Stimulates the ovaries to produce oestrogen and progesterone hormones.
- Triggers the ovaries to release an egg during ovulation.
- Promotes the development of the corpus luteum.
- Stimulate the corpus luteum to produce progesterone.
What does high luteinizing hormone mean?
The high luteinizing hormone refers to the overproduction of the luteinizing hormone, which is mainly caused by pituitary disorder, malnutrition, etc.
What does high LH mean in males?
In males, the increased levels of LH result in the primary and secondary testicular failure.
What happens if FSH is high in males?
Males with increased levels of FSH results in a genetic disorder, which affects sexual development, which often causes infertility. In some cases, Klinefelter syndrome is seen in males with increased levels of Follicle-stimulating hormone (FSH).