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Luteinizing hormone
 
 
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Luteinizing hormone (LH, also known as lutropin) is a hormone
Hormone

Hormones are chemicals released by cells that affect cells in other parts of the body. Only a small amount of hormone is required to alter cell metabolism....
 produced by the anterior pituitary gland.





is a glycoprotein
Glycoprotein

Not to be confused with peptidoglycan or proteoglycan.Glycoproteins are proteins that contain oligosaccharide chains covalently attached to their Peptide side-chains....
. Each monomeric unit is a sugar-like protein
Protein

Proteins are organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid Residue ....
 molecule; two of these make the full, functional protein.

Its structure is similar to the other glycoproteins, follicle-stimulating hormone
Follicle-stimulating hormone

Follicle-stimulating hormone is a hormone synthesized and secreted by gonadotropes in the anterior pituitary gland. FSH regulates the development, growth, pubertal maturation, and reproductive processes of the human body....
 (FSH), thyroid-stimulating hormone
Thyroid-stimulating hormone

Thyroid-stimulating hormone is a peptide hormone synthesized and secreted by thyrotrope cells in the anterior pituitary gland which regulates the endocrine function of the thyroid gland....
 (TSH), and human chorionic gonadotropin
Human chorionic gonadotropin

Human chorionic gonadotropin is a glycoprotein hormone produced in pregnancy that is made by the the developing embryo soon after Conception and later by the syncytiotrophoblast ....
 (hCG). The protein dimer contains 2 polypeptide units, labeled alpha and beta subunits that are connected by two disulfide bridges:





The different composition of these oligosaccharide
Oligosaccharide

An oligosaccharide is a saccharide polymer containing a small number of component sugars, also known as simple sugars. The name derived from the Greek oligos, meaning "a few"....
s affects bioactivity and speed of degradation.






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Encyclopedia


Luteinizing hormone (LH, also known as lutropin) is a hormone
Hormone

Hormones are chemicals released by cells that affect cells in other parts of the body. Only a small amount of hormone is required to alter cell metabolism....
 produced by the anterior pituitary gland.

  • In the female, an acute rise of LH – the LH surge – triggers ovulation
    Ovulation

    Ovulation is the process in the menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum that participates in reproduction....
    .


  • In the male, where LH had also been called Interstitial Cell Stimulating Hormone (ICSH), it stimulates Leydig cell
    Leydig cell

    Leydig cells, also known as interstitial cells of Leydig, are found adjacent to the seminiferous tubules in the testes. They can secrete testosterone and are often closely related to nerves....
     production of testosterone
    Testosterone

    Testosterone is a steroid hormone from the androgen group. In mammals, testosterone is primarily secreted in the testis of males and the ovaries of females, although small amounts are also secreted by the adrenal glands....
    .


Structure

LH is a glycoprotein
Glycoprotein

Not to be confused with peptidoglycan or proteoglycan.Glycoproteins are proteins that contain oligosaccharide chains covalently attached to their Peptide side-chains....
. Each monomeric unit is a sugar-like protein
Protein

Proteins are organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid Residue ....
 molecule; two of these make the full, functional protein.

Its structure is similar to the other glycoproteins, follicle-stimulating hormone
Follicle-stimulating hormone

Follicle-stimulating hormone is a hormone synthesized and secreted by gonadotropes in the anterior pituitary gland. FSH regulates the development, growth, pubertal maturation, and reproductive processes of the human body....
 (FSH), thyroid-stimulating hormone
Thyroid-stimulating hormone

Thyroid-stimulating hormone is a peptide hormone synthesized and secreted by thyrotrope cells in the anterior pituitary gland which regulates the endocrine function of the thyroid gland....
 (TSH), and human chorionic gonadotropin
Human chorionic gonadotropin

Human chorionic gonadotropin is a glycoprotein hormone produced in pregnancy that is made by the the developing embryo soon after Conception and later by the syncytiotrophoblast ....
 (hCG). The protein dimer contains 2 polypeptide units, labeled alpha and beta subunits that are connected by two disulfide bridges:

  • The alpha subunits of LH, FSH, TSH, and hCG are identical, and contain 92 amino acids.


  • The beta subunits vary. LH has a beta subunit of 121 amino acids (LHB) that confers its specific biologic action and is responsible for interaction with the LH receptor. This beta subunit contains the same amino acids in sequence as the beta sub unit of hCG
    Human chorionic gonadotropin

    Human chorionic gonadotropin is a glycoprotein hormone produced in pregnancy that is made by the the developing embryo soon after Conception and later by the syncytiotrophoblast ....
     and both stimulate the same receptor, however, the hCG beta subunit contains an additional 24 amino acids, and both hormones differ in the composition of their sugar moieties.


The different composition of these oligosaccharide
Oligosaccharide

An oligosaccharide is a saccharide polymer containing a small number of component sugars, also known as simple sugars. The name derived from the Greek oligos, meaning "a few"....
s affects bioactivity and speed of degradation. The biologic half-life
Half-life

The half-life of a quantity whose value decreases with time is the interval required for the quantity to decay to half of its initial value. The concept originated in describing how long it takes atoms to undergo radioactive decay but also applies in a wide variety of other situations....
 of LH is 20 minutes, shorter than that of FSH (3-4 hours) or hCG (24 hours).

Genes

The gene
Gene

A gene is the basic unit of heredity in a living organism. All living things depend on genes. Genes hold the information to build and maintain their cell and pass genetic trait to offspring....
 for the alpha subunit is located on chromosome 6q12.21.

The luteinizing hormone beta subunit gene is localized in the LHB/CGB gene cluster on chromosome 19q13.32. In contrast to the alpha gene activity, beta LH subunit gene activity is restricted to the pituitary gonadotropic cells. It is regulated by the gonadotropin releasing hormone from the hypothalamus
Hypothalamus

The hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland ....
. Inhibin
Inhibin

Inhibin is a peptide that is an Enzyme inhibitor of FSH synthesis and secretion, and participates in the regulation of the menstrual cycle....
, activin
Activin

Activin is a peptide that enhances follicle-stimulating hormone Chemical synthesis and secretion and participates in the regulation of the menstrual cycle....
, and sex hormones do not affect genetic activity for the beta subunit production of LH.

Activity

In both males and females, LH is essential for reproduction.

  • In females, at the time of menstruation, FSH initiates follicular growth, specifically affecting granulosa cell
    Granulosa cell

    A granulosa cell is a somatic cell of the sex cord that is closely associated with the developing female gamete in the ovary of mammals....
    s. With the rise in estrogen
    Estrogen

    Estrogens are a group of steroid compounds, named for their importance in the estrous cycle, and functioning as the primary female sex hormone....
    s, LH receptors are also expressed on the maturing follicle that produces an increasing amount of estradiol
    Estradiol

    Estradiol is a sex hormone. Mislabelled the "female" hormone, it is also present in males; it represents the major estrogen in humans. Estradiol has not only a critical impact on reproductive and sexual functioning, but also affects other organs including bone structure....
    . Eventually at the time of the maturation of the follicle, the estrogen rise leads via the hypothalamic interface to the “positive feed-back” effect, a release of LH over a 24-48 hour period. This 'LH surge' triggers ovulation
    Ovulation

    Ovulation is the process in the menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum that participates in reproduction....
     hereby not only releasing the egg, but also initiating the conversion of the residual follicle into a corpus luteum
    Corpus luteum

    The corpus luteum is a temporary endocrine structure in mammals, involved in production of progestogen, which is needed to maintain pregnancy....
     that, in turn, produces progesterone
    Progesterone

    Progesterone is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species. Progesterone belongs to a class of hormones called progestogens, and is the major naturally occurring human progestogen....
     to prepare the endometrium
    Endometrium

    The endometrium is the inner membrane of the mammalian uterus....
     for a possible implantation
    Implantation

    Implantation is an event that occurs early in pregnancy in which the embryo adheres to the wall of uterus. At this stage of prenatal development, the embryo is a blastocyst....
    . LH is necessary to maintain luteal function for the first two weeks. In case of a pregnancy
    Pregnancy

    Pregnancy is the carrying of one or more offspring, known as a fetus or embryo, inside the uterus of a female. In a pregnancy, there can be multiple gestations, as in the case of twins or Multiple birth....
     luteal function will be further maintained by the action of hCG (a hormone very similar to LH) from the newly established pregnancy. LH supports thecal cells in the ovary that provide androgen
    Androgen

    Androgen is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of masculine characteristics in vertebrates by binding to androgen receptors....
    s and hormonal precursors for estradiol production.


  • In the male, LH acts upon the Leydig cells of the testis and is responsible for the production of testosterone
    Testosterone

    Testosterone is a steroid hormone from the androgen group. In mammals, testosterone is primarily secreted in the testis of males and the ovaries of females, although small amounts are also secreted by the adrenal glands....
    , an androgen
    Androgen

    Androgen is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of masculine characteristics in vertebrates by binding to androgen receptors....
     that exerts both endocrine activity and intratesticular activity such as spermatogenesis
    Spermatogenesis

    Spermatogenesis is the process by which male spermatogonia develop into mature spermatozoa. Spermatozoa are the mature male gametes in many sexually reproducing organisms....
    .


The release of LH at the pituitary gland is controlled by pulses of gonadotropin-releasing hormone
Gonadotropin-releasing hormone

Gonadotropin-releasing hormone , also known as Luteinizing-hormone releasing hormone , is a tropic hormone peptide hormone responsible for the release of follicle-stimulating hormone and luteinizing hormone from the anterior pituitary....
 (GnRH) from the hypothalamus. Those pulses, in turn, are subject to the estrogen feedback from the gonads.

Normal levels

LH levels are normally low during childhood
Childhood

Childhood is a broad term usually applied to the phase of Human_development_ in humans between Infant and adulthood....
 and, in women, high after menopause
Menopause

The Menopause is the permanent cessation of menstruation which occurs a considerable length of time before the end of the lifespan.The word was first applied to humans, and because of this it literally means the cessation of monthly cycles or menstrual cycles, from the Greek roots meno and pausis ....
.

During the reproductive years typical levels are between 5-20 mIU/ml.

Physiologic high LH levels are seen during the LH surge (v.s.); typically they last 48 hours.

Ovulation predictor kit (LH kit)

The detection of the LH surge has become useful for people who want to know when ovulation occurs. LH can be detected by urinary ovulation predictor kits (OPK, also LH-kit) that are performed daily around the time ovulation may be expected. The conversion from a negative to a positive reading would suggest that ovulation is about to occur within 24-48 hours, giving you two days to engage in sexual intercourse with the intentions of conceiving. Couples who plan to conceive would time intercourse accordingly.

As sperm can stay viable in the woman for several days, such tests are not recommended for contraceptive practices. [note: photo shows "negative" results, i.e. no LH surge]

Disease states


Relative elevations


In children with precocious puberty
Precocious puberty

Precocious puberty is an unusually early onset of puberty, the process of sexual maturation triggered by the brain or exogenous chemicals, which usually begins in late childhood and results in reproductive maturity and completion of growth....
 of pituitary or central origin, LH and FSH levels may be in the reproductive range instead of the low levels typical for their age.

During the reproductive years, relatively elevated LH is frequently seen in patients with the polycystic ovary syndrome
Polycystic ovary syndrome

Polycystic ovary syndrome is an endocrine disorder that affects approximately 5% of all women.It occurs amongst all races and nationalities, is the most common hormonal disorder among women of reproductive age, and is a leading cause of infertility....
; however it would be unusual for them to have LH levels outside of the normal reproductive range.

High LH levels

Persistently high LH levels are indicative of situations where the normal restricting feedback from the gonad is absent, leading to a pituitary production of both LH and FSH. While this is typical in the menopause, it is abnormal in the reproductive years. There it may be a sign of:
  1. Premature menopause
  2. Gonadal dysgenesis
    Gonadal dysgenesis

    Gonadal dysgenesis generally refers to a condition where gonadal development is atypical, often only presenting streaks of connective tissue: so-called streak gonads....
    , Turner syndrome
    Turner syndrome

    Turner syndrome or Ullrich-Turner syndrome encompasses several conditions, of which monosomy X is most common. It is a chromosomal disorder in which all or part of one of the sex chromosomes is absent....
  3. Castration
    Castration

    Castration is any action, surgery, chemical castration, or otherwise, by which a male loses the functions of the testicles. In common usage the term is usually applied to males, although as a medical term it is applied to both males and females....
  4. Swyer syndrome
    Swyer syndrome

    Swyer syndrome, or XY gonadal dysgenesis, is a type of hypogonadism in which no functional gonads are present to induce puberty in an externally female person whose karyotype is then found to be XY....
  5. Polycystic Ovary Syndrome
    Polycystic ovary syndrome

    Polycystic ovary syndrome is an endocrine disorder that affects approximately 5% of all women.It occurs amongst all races and nationalities, is the most common hormonal disorder among women of reproductive age, and is a leading cause of infertility....
  6. Certain forms of CAH
    CAH

    CAH can stand for:* Congenital adrenal hyperplasia* Calcium Aluminate Hydrate, an important phase in cement chemistry* Crime against humanity* Capital Airports Holding Company, Airport holdings company in the People's Republic of China....
  7. Testicular failure


Deficient LH activity

Diminished secretion of LH can result in failure of gonadal function (hypogonadism). This condition is typically manifest in males as failure in production of normal numbers of sperm. In females, amenorrhea is commonly observed. Conditions with very low LH secretions are:
  1. Kallmann syndrome
    Kallmann syndrome

    Kallmann syndrome is an example of hypogonadism caused by a deficiency of gonadotropin-releasing hormone , which is created by the hypothalamus....
  2. Hypothalamic suppression
  3. Hypopituitarism
    Hypopituitarism

    Hypopituitarism is the decreased secretion of one or more of the eight hormones normally produced by the pituitary gland at the base of the brain....
  4. Eating disorder
    Eating disorder

    An eating disorder is a compulsion to eat, or avoid eating, that negatively affects both one's physical and mental health. Eating disorders are all encompassing....
  5. Hyperprolactinemia
  6. Gonadotropin deficiency
  7. Gonadal suppression therapy
    1. GnRH antagonist
    2. GnRH agonist (downregulation)


Availability

LH is available mixed with FSH in the form of Pergonal, and other forms of urinary gonadotropins . More purified forms of urinary gonadotropins may reduce the LH portion in relation to FSH. Recombinant LH is available as lutropin alfa (Luveris). All these medications have to be given parenterally. They are commonly in infertility therapy to stimulate follicular development, notably in IVF therapy.

Often, hCG medication is used as an LH substitute because it activates the same receptor. Medically used hCG is derived from urine of pregnant women, less costly, and has a longer half-life than LH.

External links