Luteinizing Hormone

Luteinizing hormone (LH) is a hormone with a vital role in the endocrine system, particularly regarding reproductive health. Understanding LH and its functions is crucial for comprehending various aspects of fertility, menstrual cycles, and hormonal balance in both men and women. 

Luteinizing Hormone (LH) is created by your pituitary gland in the brain. For women, LH is the key player in the luteal phase of the menstrual cycle, causing ovulation - the release of a mature egg from the ovary. 

For men, LH is responsible for the production of testosterone, a hormone necessary for the development of male secondary sexual characteristics and sperm production. 

In this article, we will delve into the definition and characteristics of LH, exploring its structure and functions within the body. Additionally, we will examine the role of LH in female and male reproductive health, and how LH levels are tested. Furthermore, we will explore methods to increase LH levels naturally or through medical interventions, as well as what low LH levels may indicate for an individual's health. 

Through this exploration, readers will gain a deeper understanding of the importance of LH and its implications for overall well-being.

What is Luteinizing Hormone?

Definition of Luteinizing Hormone: What is Luteinizing Hormone (LH)?

LH is a crucial hormone produced by the anterior pituitary gland, a pea-sized structure located in the brain. Structurally, LH is a glycoprotein hormone composed of an alpha and beta subunit. 

In both men and women, LH is an important hormone in regulating reproductive function.  Through a complex series of messages sent along the hypothalamic-pituitary-gonadal (HPG) axis, LH helps stimulate and regulate key reproductive functions.  LH exerts its effects primarily on the gonads—specifically, the ovaries in females and the testes in males. 

Production and Secretion of Luteinizing Hormone

Where is Luteinizing Hormone Produced?

LH is primarily secreted by the anterior pituitary gland in response to signals from the hypothalamus. Within the anterior pituitary, specialized cells known as gonadotropes are responsible for synthesizing and releasing LH in response to regulatory signals from the hypothalamus. 

The hypothalamus produces and releases gonadotropin-releasing hormone (GnRH), which acts as the primary stimulator of LH secretion. GnRH is transported via the hypothalamic-pituitary portal system to the anterior pituitary, where it binds to receptors on gonadotropes, triggering the synthesis and release of LH into the bloodstream. 

Once in circulation, LH travels to the gonads—ovaries in females and testes in males—where it exerts its effects on reproductive function.

The relationship between the hypothalamus, the pituitary gland, and the ovaries or testes is called the hypothalamic-pituitary-gonadal (HPG) axis.  

The HPG axis is a complex regulatory system in the body responsible for coordinating the production and release of reproductive hormones, with the hypothalamus releasing gonadotropin-releasing hormone (GnRH), stimulating the pituitary gland to secrete luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which in turn act on the gonads to regulate the synthesis of sex hormones and gametogenesis.

Regulation of LH Production and Secretion

The production and secretion of luteinizing hormone (LH) are tightly regulated by a complex feedback system that controls the HPG axis.   

GnRH, produced by hypothalamic neurons, stimulates the synthesis and release of LH from the anterior pituitary in response to various stimuli, including changes in sex steroid hormone levels and environmental factors in the blood. 

GnRH secretion occurs in a pulsatile manner, with the frequency and amplitude of pulses influencing LH release. Specifically, negative feedback mechanisms play a crucial role in regulating LH secretion. 

In men, LH secretion is primarily regulated by negative feedback from testosterone levels, where high testosterone levels inhibit LH production via the hypothalamic-pituitary-gonadal axis.

In women, LH secretion is tightly regulated by the pulsatile release of gonadotropin-releasing hormone (GnRH) from the hypothalamus, which stimulates LH release from the pituitary gland, particularly during the mid-menstrual cycle surge, triggering ovulation and promoting the development of the corpus luteum.

Functions of Luteinizing Hormone (LH): What Does Luteinizing Hormone Do?

In females, the surge of LH triggers the rupture of the mature ovarian follicle, releasing the egg into the fallopian tube during ovulation. Additionally, LH stimulates the production of progesterone by the corpus luteum, which is crucial for maintaining the uterine lining during the menstrual cycle. 

In males, LH stimulates the Leydig cells in the testes to produce testosterone, which is essential for the development and maintenance of male reproductive tissues and secondary sexual characteristics. 

Overall, LH plays a central role in regulating the menstrual cycle in females and spermatogenesis and testosterone production in males.

Overview of the Role of LH in the Endocrine System

Along with follicle-stimulating hormone (FSH), LH is a gonadotropin that is crucial to regulating the reproductive system. 

Upon secretion, LH acts on the gonads—specifically, the ovaries in females and the testes in males—where it stimulates various processes essential for reproductive function. LH secretion is tightly regulated by gonadotropin-releasing hormone (GnRH) from the hypothalamus, forming a complex feedback loop that ensures proper reproductive health in both men and women. 

In females, LH surge triggers ovulation, the release of a mature egg from the ovary, and supports the development of the corpus luteum, which produces progesterone necessary for the preparation and maintenance of the uterine lining for potential implantation. Any disruptions in LH levels or function can lead to reproductive disorders, such as infertility, menstrual irregularities, and hormonal imbalances.

Role of LH in Female Reproductive Health

In female reproductive health, luteinizing hormone (LH) plays a pivotal role in regulating the menstrual cycle and ovulation. During the menstrual cycle, LH levels surge in response to rising estrogen levels, triggering the release of a mature egg from the ovary during ovulation. 

This pulsatile rise in LH, often referred to as the LH surge, stimulates the rupture of the ovarian follicle, releasing the egg into the fallopian tube where it can be fertilized by sperm. 

LH is also essential for the development and maintenance of the corpus luteum, a temporary endocrine structure that forms from the remnants of the ovarian follicle after ovulation. 

The corpus luteum produces progesterone, which is crucial for preparing the uterine lining for potential implantation of a fertilized egg and supporting early pregnancy.  If fertilization does not occur the corpus luteum regresses, leading to a decline in LH levels and the start of a new menstrual cycle.

LH plays a critical role in the reproductive health of women by regulating ovulation and progesterone production during the luteal phase of the menstrual cycle.

Role of LH in Male Reproductive Health 

Luteinizing hormone (LH) plays a crucial role in male reproductive health by acting on Leydig cells in the testes to stimulate the production and secretion of testosterone. 

Upon binding to its receptors on Leydig cells, LH triggers the synthesis and release of testosterone, which is essential for the development and maintenance of male reproductive organs, including the testes and accessory glands. 

Testosterone is also crucial for the initiation and maintenance of spermatogenesis, the process of sperm production, as well as the development of secondary sexual characteristics such as facial hair growth, deepening of the voice, and muscle mass. 

Additionally, LH acts synergistically with follicle-stimulating hormone (FSH) to support optimal sperm production and maturation within the seminiferous tubules of the testes, ensuring fertility and overall reproductive function in men.

Role of LH in Fetal and Early Human Development [10.]

During fetal development, luteinizing hormone (LH) and human chorionic gonadotropin (hCG) are pivotal hormones for both male and female sexes, with their levels fluctuating throughout gestation. 

In male fetuses hCG initially dominates, contributing significantly to testosterone production by Leydig cells before LH takes over around weeks 15 to 20. Anencephalic male fetuses lacking LH exhibit normal reproductive tract development initially, but struggle with external genitalia development as hCG levels decline. 

In contrast, female fetuses experience higher peak levels of LH, likely due to lack of negative feedback from testosterone than male fetuses experience.  Female fetuses have lower levels of gonadal hormones in utero because their reproductive tract development is less reliant on gonadal hormone levels.  Females have less steroidogenesis until after delivery, as LH receptors in the ovaries only express later in gestation.

After delivery, both male and female infants experience a surge in LH levels due to estrogen withdrawal from the mother, followed by a gradual decline to low basal levels until prepuberty. 

During puberty, there is a gradual increase in LH secretion, initially nocturnal, then transitioning to a pulsatile pattern throughout the day, stimulating gonadal steroidogenesis essential for maturation in males and females.

Testing for Luteinizing Hormone

Overview of LH Testing Options

Luteinizing hormone (LH) levels can be assessed through various testing options, including blood tests and urine tests. 

Blood tests are the most common method and involve drawing a blood sample, typically from a vein in the arm, which is then analyzed in a laboratory to measure LH levels. 

Urine tests, on the other hand, often utilize LH detection kits that allow individuals to test their urine at home. These kits detect LH surge, which is particularly useful for tracking ovulation in women. 

Additionally, LH levels can also be assessed through saliva tests, although these are less common.  Cycle mapping tests that monitor hormone levels throughout a woman’s entire cycle tend to utilize urine or saliva tests. 

Procedures for LH Testing

For blood LH testing, a healthcare professional will typically draw a blood sample, usually in the morning when hormone levels are most stable. The sample is then sent to a laboratory for analysis, where LH levels are measured using specialized equipment. 

Urine LH testing can be done at home using LH detection kits, which involve collecting a urine sample and applying it to the test strip according to the manufacturer's instructions. Results are usually available within minutes. 

Saliva LH testing involves collecting a saliva sample using a specialized kit to assess LH levels; while it does correlate with serum levels to demonstrate an LH surge, this method is less commonly used and may require specific instructions for collection and analysis.  Samples are typically shipped to a lab for analysis.  [7.]  

Reference Ranges for LH

LH reference ranges vary depending on age, sex, and sample type.  Additionally, reference ranges may vary among labs.  

A typical reference range for LH in blood is [8., 11.]

Adults:

Male: 1.24-7.8 IU/L

Female:

Follicular phase: 1.68-15 IU/L

Ovulatory peak : 21.9-56.6 IU/L

Luteal phase: 0.61-16.3 IU/L

Postmenopause: 14.2-52.3 IU/L

Child (age 1-10 years):

Male: 0.04-3.6 IU/L

Female: 0.03-3.9 IU/L

Typical reference ranges indicating an LH surge in urine testing is about 20 to 100 mIU/ml.  [14.]  Following the LH surge, ovulation was most commonly detected during ultrasonography 20+/- 3 hours later.  [14.]

Questions regarding reference ranges for salivary testing of LH should be directed to the companies offering them.  

Clinical Significance of LH Testing

LH testing plays a crucial role in diagnosing and monitoring various reproductive disorders and conditions. 

In women, LH levels are often measured alongside other hormones like follicle-stimulating hormone (FSH) to assess ovarian function, predict ovulation, and evaluate fertility issues. Elevated or suppressed LH levels may indicate conditions such as polycystic ovary syndrome (PCOS), ovarian failure, or pituitary disorders. 

In men, LH testing is used to evaluate testicular function and diagnose conditions such as hypogonadism and infertility. Abnormal LH levels in men may suggest problems with the hypothalamus, pituitary gland, or testes, warranting further investigation and treatment.

Specific clinical conditions associated with alterations in LH from expected values include: 

LH in Polycystic Ovarian Syndrome (PCOS)

• In PCOS, the LH:FSH ratio is often elevated due to persistent rapid pulses of GnRH, leading to increased LH secretion relative to FSH.
• The skewed LH:FSH ratio contributes to the overproduction of androgens by the theca cells of the ovaries, leading to symptoms such as hirsutism, menstrual irregularities, and infertility.
• Elevated LH levels in PCOS can disrupt normal follicle development and ovulation, contributing to the characteristic features of the syndrome, including multiple small ovarian follicles and anovulation.

Ovarian Failure and Altered LH Levels

• Premature ovarian failure (POF) or primary ovarian insufficiency (POI) is characterized by elevated levels of LH due to the lack of negative feedback from the ovaries.
• In POF/POI, diminished ovarian function leads to decreased estrogen production, resulting in elevated LH levels as the hypothalamus and pituitary attempt to stimulate ovarian activity.
• This process may be normal as a woman transitions into perimenopause and menopause, or it may signal an underlying medical condition. 
• Elevated LH levels in POF/POI contribute to menstrual irregularities, infertility, and symptoms of estrogen deficiency such as hot flashes and vaginal dryness.

Hypothalamic Amenorrhea and Altered LH Levels

• Hypothalamic amenorrhea is a condition characterized by the absence of menstruation due to disruptions in the HPG axis in women.  Low levels of luteinizing hormone (LH) are commonly observed in women with hypothalamic amenorrhea.
• Hypothalamic amenorrhea can result from various factors, including excessive exercise, stress, low body weight or malnutrition, and psychological factors.
• It results in suppressed GnRH secretion from the hypothalamus and leads to decreased LH production by the anterior pituitary gland, contributing to low LH levels.
• Hypothalamic amenorrhea ultimately results in absent or Impaired ovulation: insufficient LH levels disrupt the menstrual cycle, leading to anovulation and infertility.

Pituitary Disorders and Altered LH Levels

• Pituitary adenomas can disrupt LH secretion, leading to altered levels of the hormone.
• In cases where the adenoma secretes excess LH, it can lead to conditions such as ovarian hyperstimulation syndrome.
• Conversely, pituitary disorders such as hypopituitarism or pituitary tumors can result in decreased LH secretion, causing hypogonadism and associated symptoms such as menstrual irregularities and infertility in women.

Infertility and Assisted Reproductive Technology (ART)

• Low LH levels can negatively impact outcomes in assisted reproductive technologies (ART), such as in vitro fertilization (IVF) and intrauterine insemination, by affecting follicle development and ovulation.
• Supplementing ART with exogenous LH, particularly in patients with hypogonadotropic hypogonadism, has been shown to improve pregnancy outcomes by enhancing follicle maturation and 17-beta-estradiol production.
• However, excessive LH levels before ovulation can have detrimental effects on ART outcomes, leading to granulosa cell inhibition, follicle atresia, and impaired embryo implantation.

Testicular Dysfunction in Chronic Kidney Disease (CKD)

• Symptoms of testicular dysfunction in CKD include low libido, potency, and testicular size, often accompanied by decreased testosterone production and impaired spermatogenesis.
• Elevated levels of LH in end-stage renal disease contribute to testicular dysfunction by affecting testosterone concentration and spermatogenesis, with higher LH levels associated with lower gonadotropin receptor function in the testes.
• Testicular dysfunction and altered LH levels can be reversed after renal transplantation, highlighting the role of LH in maintaining testicular function.

Hypogonadotropic Hypogonadism in Males

• Hypogonadotropic hypogonadism is characterized by low levels of FSH and LH due to dysfunction in the hypothalamic-pituitary-gonadal axis, resulting in reduced testosterone production and spermatogenesis.
• Treatment options for hypogonadotropic hypogonadism include pulsatile administration of GnRH or LH (or hCG) and FSH, which can help stimulate spermatogenesis and increase sperm concentration in the ejaculate, although assisted reproductive technologies may still be necessary for conception.

What Does Low Luteinizing Hormone Mean?

Causes and Implications of Low LH Levels

Low luteinizing hormone (LH) levels can stem from various factors, including hypothalamic or pituitary dysfunction, primary ovarian failure, or certain medications. 

In women, low LH levels may indicate hypothalamic amenorrhea, a condition characterized by reduced GnRH secretion due to stress, excessive exercise, or low body weight. Similarly, pituitary disorders such as hypopituitarism can lead to decreased LH production, disrupting the normal menstrual cycle and fertility. 

In men, low LH levels may signal hypogonadotropic hypogonadism, where insufficient LH secretion results in impaired testosterone production and testicular function. Additionally, certain medications like corticosteroids or opioids can suppress LH secretion, leading to hormonal imbalances and reproductive issues.

Clinical Considerations and Treatment Options for Low LH

The clinical implications of low LH levels depend on the underlying cause and its impact on reproductive health. 

In women, addressing factors contributing to hypothalamic dysfunction such as stress reduction, adequate nutrition, or hormonal therapy, may help restore normal LH secretion and menstrual function. 

Similarly, for men with hypogonadotropic hypogonadism, treatment often involves hormone replacement therapy to supplement deficient LH levels and stimulate testosterone production. 

However, the treatment approach varies based on individual factors such as age, overall health, and fertility goals. Regular monitoring of LH levels through blood tests is essential to assess treatment efficacy and adjust interventions accordingly, aiming to optimize reproductive outcomes and overall well-being.

How to Increase Luteinizing Hormone

Natural Methods to Boost LH Levels

Diet: maintain a balanced diet rich in essential nutrients, including antioxidants, vitamins, and minerals, which can support overall reproductive health.  Additionally, eating enough calories is essential to maintain hypothalamic production of GnRH.  [9.]

Exercise: engage in regular exercise to promote blood circulation and hormone balance.  [5., 15.]

‍Stress: manage stress through relaxation techniques such as meditation, yoga, or deep breathing exercises, as stress can negatively impact hormone levels and impair hypothalamic release of GnRH.  [13.]

Sleep: get adequate sleep to ensure proper hormone regulation and overall well-being. [3.]

Acupuncture: consider acupuncture or acupressure, which may help regulate hormone levels and improve reproductive function.  [2.]

Herbal Support: explore herbal supplements such as vitex (chasteberry) or red clover which are believed to support hormonal balance and ovarian function.  [1.] 

Healthy Weight Management: maintain a healthy weight, as obesity or being underweight can disrupt hormone levels and fertility.  [4.] 

Avoid Endocrine-Disrupting Chemicals: limit exposure to environmental toxins and endocrine-disrupting chemicals found in certain plastics, pesticides, and personal care products, as they can interfere with hormone regulation.  [12.]

Consult with a healthcare provider or naturopathic doctor for personalized recommendations and guidance on natural therapies to support normal LH cycling.

Specific Tests to Assess LH Levels

Click here for specific tests to assess LH levels in men and women.