What is Luteinizing Hormone?

by Benjamin Bunting BA(Hons) PGCert

ben bunting BA(Hons) PgCert Sport & Exercise Nutriton  Written by Ben Bunting: BA(Hons), PGCert. Sport & Exercise Nutrition. L2 Strength & Conditioning Coach.

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What is Luteinizing Hormone?

Luteinizing hormone (LH) is a hormone produced by the gonadotropic cells of the anterior pituitary gland. It is regulated by the gonadotropin-releasing hormone from the hypothalamus. It triggers the development of the corpus luteum and ovulation in females. 

It helps regulate the reproductive system in women and men, although its levels are lower in women. In men, it stimulates the Leydig cells in the testes to produce testosterone, which acts locally to support sperm production and generate male characteristics.

Function

LH is made in the pituitary gland and is part of the endocrine system, which is a group of glands and organs in the body. It regulates fertility by stimulating the production of testosterone and progesterone. The hormone is produced during ovulation and is essential for both males and females to conceive.

In males, it plays a significant role in promoting fertility. However, its role in female reproduction is not fully understood. This hormone regulates the menstrual cycle and does not surge during pregnancy. It plays a vital role in the development of the fetus, as well as getting the body ready for childbirth. Unfortunately, researchers have also observed an increased risk of endometrial cancer in girls and women with homozygous gene mutations.

The luteinizing hormone acts on the G-protein coupled receptor. It activates adenylyl cyclase, which then increases the intracellular concentration of cyclic AMP. Furthermore, cyclic AMP stimulates protein kinase A, which phosphorylates specific intracellular proteins.

Luteinizing Hormone in Men 

As mentioned, a low level of luteinizing hormone in men can affect fertility particularly as this hormone is essential for sperm production. Fortunately, many fertility treatments are available that aim to regulate the levels of LH. A low level of LH in men may not necessarily be cause for alarm, but a low level can have serious implications for the ability of a couple to conceive.

LH is important for the reproductive system and is produced by the anterior pituitary gland. In men, it helps promote testosterone production, which is a vital part of the sperm and gives men their male characteristics.

A test for luteinizing hormone in men can also be useful for checking the pituitary gland. The pituitary gland is responsible for producing this hormone and releases it in the blood. It is also responsible for maturing primordial germ cells in men, which is a precursor to both sperm and eggs.

Luteinizing hormone and women

LH is a key player in regulating the development of the corpus luteum and ovulation in females. This hormone is produced by gonadotropin-releasing cells located in the anterior pituitary gland, and the production is regulated by the hypothalamus, the hormone's governing center. 

Women who take certain medicines or take certain birth control pills may experience an abnormality in the levels of luteinizing hormone. This means that the results of the LH test may not be accurate. A person who uses these drugs needs to consult a physician. 

A luteinizing hormone test will measure the levels of LH in blood and urine. It can help identify the cause of infertility or detect problems with the pituitary gland. If LH levels are high, you will not be ovulating.

High LH levels can be a sign of sex organ failure, meaning the ovaries and testes are no longer producing enough hormones. Other causes of high LH levels include genetic conditions, autoimmune conditions, and surgical conditions. Women who are suffering from polycystic ovary syndrome may also have elevated levels of LH.

Testosterone production

The LH is a hormone essential to the production of testosterone in men and women. When it is produced by the anterior pituitary gland and travels to the testes to trigger testosterone production. The hormone also stimulates the release of other hormones, such as progesterone.

When a man's testosterone levels decline, the anterior pituitary gland responds by producing a larger quantity of luteinizing hormone. The hormone is then pushed into the bloodstream, where it serves a variety of functions.

Increasing testosterone levels is critical for both the body and sex life. Higher levels of testosterone promote larger muscle growth, increased sexual performance, and enhanced libido. Higher levels of testosterone also result in stronger stamina and a more stable mood.

Testosterone production by Leydig cells

Researchers identified the Leydig cell as the source of the production of luteinizing hormone in mice. The Leydig cells are found in the Platyrhini lineage. Interestingly, these cells appear clustered and cannot be counted accurately. To normalize testosterone secretion, the researchers determined the activity of 3b-hydroxysteroid dehydrogenase, a marker enzyme of Leydig cells. They found that basal testosterone production was fourfold higher in PDE8A-KO mice than in wild-type mice.

The receptors for human LH and murine hCG are different but show similarity in downstream steroid synthesis. However, human LH and hCG may not be regulated by the same receptors in murine Leydig cells, making them inappropriate for clinical studies requiring human LH.

Studies have shown that PDE8A regulates the synthesis of testosterone and LH in mouse Leydig cells. PDE8A is a potent pharmacological target for modulating testosterone synthesis. However, the function of PDE8A has not been fully characterized, making it important to determine whether it is essential for Leydig cell function. 

Earlier studies have identified Leydig cells as the source of luteinizing hormone. However, there are a number of barriers that limit the production of luteinizing hormone in humans. For example, some studies have implicated the involvement of PkA, PkB, and pErk1/2 in the production of testosterone. However, this is only one of the many ways the Leydig cells regulate testosterone.

Deficiency in luteinizing hormone

A deficiency of LH can be a genetic condition, affecting both sexes. This condition results in sexual dysfunction and infertility. 

LH secretion is regulated by the hypothalamic-pituitary-gonadal axis. LH stimulates the release of Gonadotrophin-releasing hormone and follicle-stimulating hormone, two hormones produced by the ovary. LH binds to receptors in the ovaries and testes.

A genetic test for LH is available. The mutation causes a defect in the beta subunit of the gene. The karyotype of the patient was 46,XY. The luteinizing hormone beta-subunit gene sequence revealed a single-nucleotide adenine-to-adenine substitution in exon 2.

In addition, a homozygous missense mutation in the gene replaced glycine with aspartic acid at position 36. The beta and alpha subunits are co-precipitated. In addition to LH, the beta subunit also promotes the transport of cholesterol into the inner mitochondrial membrane.

Low levels of LH

There are many reasons why luteinizing hormone could be low in women, but in general, it is a sign that your pituitary gland is not functioning properly. This can affect your reproductive process and sexual development. Symptoms may include infertility, insufficient testosterone or insufficient estrogen. In some cases, it can also be a sign of a pituitary problem such as Kallmann syndrome. This is a rare disorder involving the pituitary gland and results in inadequate production of both testosterone and estrogen. Another possible cause is a condition called functional hypothalamic amenorrhea, which is linked to exercise.

How to Increase Luteinizing Hormone Naturally

While there are no proven methods of naturally boosting LH levels, there are a few lifestyle changes you can make to help your body produce more of this essential hormone.

Your diet, exercise, and stress levels play a crucial role in the regulation of hormone levels and your reproductive health. Therefore, examining your lifestyle and making changes where necessary is essential.

The Normal Range For Luteinizing Hormone

A woman's LH levels are typically in the range of five to twenty-five international units per liter. They are highest at ovulation.  In men, too little LH can lead to low levels of GnRH, leading to deficiency in GnRH secretion and infertility.

Women

  • Women, follicular phase of menstrual cycle: 1.37 to 9 IU/L

  • Women, midcycle peak: 6.17 to 17.2 IU/L

  • Women, luteal phase: 1.09 to 9.2 IU/L

  • Women, postmenopausal: 19.3 to 100.6IU/L

Men

Here are normal ranges:

  • Men: 1.42 to 15.4 IU/L

Conclusion

In humans, luteinizing hormone is produced by gonadotroph cells. These cells are large and round in shape and contain prominent endoplasmic reticulum and Golgi apparatus. They are distributed throughout the anterior pituitary gland. They account for 10 to 15% of the functional anterior pituitary cell mass. Luteinizing hormone is responsible for ovulation and the functioning of the corpus luteum.

The amount of this hormone varies depending on the woman's age, stage of sexual development, and menstrual cycle. In men, a high level of LH may cause testicular failure and infertility. It may also lead to shrinkage of the testes and insufficient testosterone production.

Women suffering from various hormonal disorders may also have elevated levels of luteinizing hormone. This hormone is necessary to stimulate ovarian function and may indicate ovulation. It is also helpful in determining the timing of perimenopause and the chances of becoming pregnant. 

 

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