It is produced by both men and women. It is known as gonadotropin and affects the sexual organs of both sexes.
Luteinizing hormone (LH), in women, affects the ovaries, and in men, it affects the testes. Luteinizing hormone plays a role in puberty, menstruation, and fertility .
The amount of luteinizing hormone in your blood can indicate underlying problems associated with a variety of reproductive health problems.
Luteinizing hormone is a hormone that is made in the pituitary gland. The pituitary gland is located at the base of the brain , and is about the size of a pea.
If you are a woman, luteinizing hormone is an important part of your menstrual cycle. It works with follicle stimulating hormone, which is another gonadotropin produced in the pituitary gland .
Follicle stimulating hormone stimulates the ovarian follicle and causes the egg to grow. It also triggers the production of estrogen in the follicle.
The increase in estrogen tells your pituitary gland to stop making FSH and to start making more luteinizing hormone. The switch to luteinizing hormone causes the egg to release from the ovary, a process called ovulation.
In the empty follicle, cells proliferate, turning it into a corpus luteum. This structure releases progesterone, a hormone necessary to maintain pregnancy. If pregnancy does not occur, progesterone levels drop and the cycle begins anew.
If you are a man, your pituitary gland also produces luteinizing hormone. The hormone binds to receptors on certain cells in your testes called Leydig cells. This leads to the release of testosterone, a hormone necessary to make sperm cells.
Luteinizing hormone is a glycoprotein hormone produced by the anterior pituitary gland.
In women, its sudden increase at the end of the follicular phase triggers ovulation and the development of the corpus luteum.
In the male, it is also called interstitial cell stimulating hormone, and it triggers the production of testosterone by the Leydig cells of the testicle.
Luteinizing hormone is easily measured in serum. Although it is released in episodes, the variability is not as great as that seen with testosterone, so meaningful data can be obtained by measuring luteinizing hormone.
This is even more true when measured in conjunction with testosterone. A reduction in testosterone that is biologically significant and caused by alterations in Leydig cells should result in a compensatory increase in luteinizing hormone levels.
In contrast, a central depression in luteinizing hormone will manifest as a reduction in both luteinizing hormone and testosterone, as well as the accessory weight of the sex organs.
Any laboratory setting out to measure luteinizing hormone, follicle-stimulating hormone, or testosterone should always first measure a representative animal cohort and perform a power calculation, so that the main experiments can include an appropriate number of animals.
Previous work has found that a group size of 15 provides satisfactory power and the possibility of finding biologically significant effects, but researchers should verify this in their own laboratory before embarking on any large project.
Luteinizing hormone, like follicle-stimulating hormone, is a pulsatilely secreted glycoprotein hormone from the pituitary under the control of hormone-releasing luteinizing hormone.
It acts exclusively on the Leydig cells in the testes and is the main regulator of testosterone secretion, which is also secreted in a pulsatile way (pulses of luteinizing hormone that occur before testosterone).
Circulating plasma testosterone (or its metabolites) completes the feedback loop to the pituitary gland to modulate luteinizing hormone secretion.
The response of Leydig cells to the binding of luteinizing hormone to its receptor is mediated through a number of transduction systems, including a cyclic adenosine monophosphate cascade, a phosphoinositol-diazyglycerol, and an arachidonic acid-prostaglandin mechanism. .
Therefore, several potential modifiers of luteinizing hormone action control the overall function of the Leydig cell.
Prolactin modifies luteinizing hormone-stimulated testosterone secretion in the rat by increasing the number of luteinizing hormone receptors on the Leydig cell.
Luteinizing hormone pulses increase at puberty, both in amplitude and frequency.
Luteinizing hormone is involved in the control of Leydig cell development, as Leydig cell differentiation does not occur in the absence of luteinizing hormone, but the main impetus for its development appears to be through increased hormone. follicle stimulant.
Requirement for factors similar to epidermal growth factor
Luteinizing hormone stimulation induces rapid, transient, and sequential expression of growth factors similar to epidermal growth factor ampfiregulin, epiregulin, betacellulin, and neuregulin 1.
These are synthesized as integral granulosa cell membrane proteins that are released by proteolytic cleavage of the extracellular domain.
Upon release, they bind to epidermal growth factor tyrosine kinase receptors (ERBB2 and ERBB3).
The incubation of rodent follicles in vitro with these growth factors recapitulates the morphological and biochemical events triggered by luteinizing hormone, including the necessary process of cumulus expansion and oocyte maturation.
Mice with mutations in Are (amphiregulin) or Ereg (epiregulin) have an ovarian phenotype consistent with an in vivo role for these proteins because they show reduced cumulus expansion in response to exogenous gonadotropins.
Therefore, epidermal growth factor-like growth factors are essential mediators of the follicular response to luteinizing hormone that leads to ovulation.
Effects on ovarian blood flow
Luteinizing hormone also increases blood flow to the ovary and causes ovarian hyperemia. Luteinization is accompanied by the production of vascular endothelial growth factor and other angiogenic factors that increase vascularization.
Blood flow can be further improved by the release of histamine or perhaps prostaglandins.
Increased ovarian blood flow increases the opportunity for delivery of steroid hormones to the general circulation and for delivery to the ovary of the cholesterol-laden low-density lipoprotein necessary to support high rates of steroidogenesis.
Increased blood flow to the developing follicle may also be important for preovulatory swelling of the follicle, which is dependent on increased fluid production from the blood plasma.
What is an LH hormone blood test?
A luteinizing hormone blood test measures the amount of luteinizing hormone in the bloodstream. If you are a woman, the amount of this hormone in the bloodstream varies with age and throughout the menstrual cycle.
It also changes with pregnancy. If a doctor orders a fertility-related luteinizing hormone test, a woman may need multiple tests to track rising and falling hormone levels.
Luteinizing hormone levels can also be measured by testing a urine sample.
If you are male, your doctor may order a luteinizing hormone test to establish a baseline luteinizing hormone level. Your doctor may also measure your luteinizing hormone level after giving you an injection of gonadotropin-releasing hormone (GnRH).
Luteinizing hormone measurement after receiving this hormone can tell your doctor if you have a problem with your pituitary gland or with another part of your body.
What are the reasons for requesting an LH hormone blood test?
There are many reasons why your doctor may order a luteinizing hormone blood test. Luteinizing hormone levels are linked to menstrual problems, fertility, and the onset of puberty.
Examples of cases where a doctor may order a luteinizing hormone blood test include:
- A woman has difficulty getting pregnant, a woman has irregular or absent menstrual periods, a woman is suspected of having entered menopause.
- A man has signs of low testosterone, such as low muscle mass or decreased sex drive, a pituitary disorder is suspected, and a boy or girl appears to be entering puberty too late or too early.
Your doctor may order the luteinizing hormone blood test in coordination with other hormone measurements, such as testosterone, progesterone, FSH, and estradiol.
Menstrual cycle and menopause
If you have missed or irregular periods, your doctor may want to determine the amount of luteinizing hormone in your bloodstream to find an underlying cause.
Luteinizing hormone levels must increase after menopause because the ovaries no longer function and pick up luteinizing hormone signals.
Your doctor may order a luteinizing hormone blood test if you are having trouble conceiving.
Luteinizing hormone levels can indicate a problem with the supply of eggs in a woman’s ovaries and a man’s sperm count, both of which affect fertility.
For a younger person, a doctor may order a luteinizing hormone blood test to find the underlying causes of delayed or early puberty.
A doctor will consider whether or not a person has signs of puberty. These include breast growth and menstruation in girls, testicle and penis growth in boys, and pubic hair growth in both boys and girls.
A test of luteinizing hormone levels in your urine can be used to determine when you are ovulating. When luteinizing hormone levels start to rise, this may indicate that ovulation will likely occur within a day or two.
These types of tests can be done at home and are often used to increase the chances of conceiving. It is important to note that this is accomplished with a urine test and not with a blood test.
How is the test administered?
To administer a luteinizing hormone blood test, a healthcare professional will draw a small amount of blood from you, most likely from your arm.
The short procedure will be done in your doctor’s office or in a lab. The sample will be tested for luteinizing hormone levels.
To draw blood, a healthcare professional will wrap an elastic band around your upper arm to make your veins easier to see.
They will disinfect the skin and insert a needle into a vein on the inside of your arm. A tube attached to the needle will collect a small sample of your blood. The process is short and almost painless.
Your doctor may request that blood samples be drawn every day for several days. Because the amount of luteinizing hormone in your blood varies with your menstrual cycle, some samples may be necessary to obtain an accurate measurement of luteinizing hormone levels.
What are the risks associated with an LH hormone blood test?
There are not many risks associated with having blood drawn. The needle site may appear later, but applying pressure to it with a bandage can reduce this possibility.
The phlebitis , although rare, can occur when blood is drawn. This is when the vein becomes inflamed after taking the blood. If it does, your healthcare provider will likely ask you to apply a warm compress to the vein during the day.
If you have any type of bleeding disorder, be sure to tell your doctor to avoid complications from having blood drawn.
How should I prepare for a luteinizing hormone blood test?
Your doctor should give you exact instructions to prepare for your blood test.
You may be asked to stop taking certain medications that can affect your results, so be sure to tell your doctor about all the medications and supplements you take.
If you are a woman, you may need to stop taking birth control or other hormone pills for up to four weeks before the test. Your doctor will also want to know the date of your last period.
As with many blood draws, you may be asked to avoid eating or drinking for up to eight hours before the test.
If you had any type of test or procedure with a radioactive substance seven days before your luteinizing hormone test, tell your doctor. These substances can interfere with your test results.
Understand the results of a luteinizing hormone test
Your doctor can tell you when your test results will be available and will discuss the meaning of your levels with you.
According to the Department of Pathology and Laboratory Medicine at the University of California, San Francisco, the following values are normal levels of luteinizing hormone in blood measured in international units per liter (IU / L):
- Women in the follicular phase of the menstrual cycle: 1.9 to 12.5 IU / L.
- Women in the peak of the menstrual cycle: 8.7 to 76.3 IU / L.
- Women in the luteal phase of the menstrual cycle: 0.5 to 16.9 IU / L.
- Pregnant women: less than 1.5 IU / L.
- Women past menopause: from 15.9 to 54.0 IU / L.
- Women 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.
While each result may vary based on your unique condition, some general interpretations of luteinizing hormone results may include the following:
If you are a woman, elevated levels of luteinizing hormone and follicle-stimulating hormone may indicate a problem with your ovaries. This is known as primary ovarian failure. Some causes of primary ovarian failure can include:
- Ovaries that are not developed properly.
- Genetic abnormalities, such as Turner syndrome.
- Exposure to radiation.
- History of taking chemotherapy drugs.
- Autoimmune disorders
- Ovarian tumor.
- Thyroid or adrenal disease.
- Polycystic ovary syndrome (sop).
Low levels of luteinizing hormone and follicle-stimulating hormone can indicate secondary ovarian failure.
This means that another part of your body causes ovarian failure. In many cases, this is the result of problems with the hormone-producing areas of your brain, such as the pituitary gland .
If you are a man, high levels of luteinizing hormone may indicate primary testicular failure. The causes of this condition can include:
- Chromosomal abnormalities, such as Klinefelter syndrome.
- Gonad development failure.
- A history of viral infections, such as mumps.
- Exposure to radiation.
- History of taking chemotherapy drugs.
- Autoimmune disorders
- Tumors, such as a germ cell tumor.
Secondary testicular failure can also be due to a brain-related cause, such as a disorder in the hypothalamus.
Also, if your doctor has given you gonadotropin-releasing hormone injection and your luteinizing hormone levels have decreased or stayed the same, you are often blamed for a pituitary disease.
Low levels of luteinizing hormone in adult men can lead to low testosterone levels, which can cause symptoms such as:
- Sexual dysfunction
- Lack of sexual interest.
For boys, high levels of luteinizing hormone can cause early puberty. This is known as precocious puberty.
According to the American Association for Clinical Chemistry (AACC), girls are more likely to experience this condition than boys. The underlying causes of this can include:
- A tumor in the central nervous system.
- Trauma or brain injury.
- Inflammation or infection in the central nervous system, such as meningitis or encephalitis.
- A history of brain surgery.
- A history of irradiation to the brain.
Delayed puberty with normal or lower luteinizing hormone levels may indicate underlying disorders, including:
- Ovarian or testicular failure.
- Hormone deficiency
- Turner syndrome.
- Síndrome de klinefelter.
- Chronic infection
- An eating disorder.
Medications that can change luteinizing hormone levels include:
- Digoxin .
- Hormonal treatments.
- Birth control pills.
The luteinizing hormone test has the potential to indicate a number of disorders related to development and fertility.
If your doctor suspects that you may have a condition that affects the ovaries, testicles, or parts of the brain that make luteinizing hormone, the test can provide more information.
LH hormone deficiency
An isolated luteinizing hormone (LH) deficiency is a rare condition.
Luteinizing hormone deficiency almost always occurs in conjunction with follicle-stimulating hormone (FSH) deficiency because luteinizing hormone and follicle-stimulating hormone are secreted by the same gonadotropic cells in the pituitary.
Luteinizing hormone deficiency can manifest in women or men as delayed puberty, hypogonadism at any age, or reproductive abnormalities that can be dramatic or subtle.
Luteinizing hormone and follicle-stimulating hormone play central roles in the hypothalamic-pituitary-gonadal axis, and therefore luteinizing hormone-related conditions and follicle-stimulating hormone deficiency can be caused by hypothalamus pathology or hypophysis.
Careful analysis of the presenting problem, the patient’s general health, and the hormonal profile is often necessary to determine the cause of the luteinizing hormone deficiency and therefore the most appropriate treatment.