What is Luteinizing Hormone Deficiency?
A deficiency of luteinizing hormone has pronounced effects on human reproduction. In order to understand the consequences of a deficiency of luteinizing hormone, it is important to first understand the effect of this hormone in the human body. Luteinizing hormone (LH) is a hormone produced by pituitary gland. Luteinizing hormone is important for reproduction in both males and females. In women, luteinizing hormone maintains the menstrual cycle and ovulation (release of an egg cell from the ovary). In men, luteinizing hormone stimulates the production of another hormone called testosterone. Testosterone is important for sperm production.
Luteinizing Hormone Functions
Luteinizing hormone deficiency almost always occurs with deficiency of another hormone, follicle-stimulating hormone (FSH). This happens because both luteinizing hormone and follicle-stimulating hormone are produced by pituitary gland. A part of brain called the hypothalamus, the pituitary gland, and the gonads (sex glands) control production of various important hormones. They make up a system called the hypothalamic-pituitary-gonadal axis. It is important to understand the effects of each component of this axis on the other.
- The hypothalamus produces gonadotropin-releasing hormone (GnRH).
- Gonadotropin-releasing hormone stimulates pituitary to make luteinizing hormone and follicle-stimulating hormone.
- In females, luteinizing hormone stimulates the ovary (female gonad) to make estradiol, progesterone, and androgen hormones.
- In males, luteinizing hormone and follicle-stimulating hormone are needed for sperm production in the testes.
Therefore a deficiency of luteinizing hormone can upset the normal reproductive processes. A luteinizing hormone deficiency can result in delayed puberty and decrease in levels of hormones secreted from the gonads (hypogonadism). In adults it may not be as noticeable and only comes to the patient’s attention when there is difficulty falling pregnant (infertility).
Luteinizing Hormone Deficiency Incidence
Hypogonadism arising from luteinizing hormone deficiency affects 1 in 10,000 to 86,000 people. In majority of cases, this is associated with loss of sense of smell. This disorder featuring lack of sense of smell is called anosmia or Kallmann syndrome. Stress can also affect the levels of gonadotropin-releasing hormone and result in hypogonadism. This can disturb or stop menstruation in females. Menstruation may also stop as a result of a malfunctioning or unresponsive pituitary gland. Luteinizing hormone deficiency can affect both males and females, however, Kallmann syndrome affects males more commonly than females. Hypogonadism and dysfunctional pituitary affect both men and women.
Luteinizing Hormone Deficiency Causes
Kallmann syndrome is inherited and runs in the families. Hypogonadism may also be genetic. However, in some cases, the causes of hypogonadism cannot be found. Excessive physical activities, eating disorders, starvation, and problems with the pituitary glands, or the hypothalmus that regulates it, may all contribute to hypogonadism. Luteinizing hormone deficiency may arise from hypothalamus or pituitary causes.
Kallmann syndrome describes hypogonadism with anosmia or no sense of smell. In some cases, it can be inherited. The hypothalamus of Kallmann syndrome sufferers lacks gonadotropin-releasing hormone-producing cells. As a result, the pituitary glands is not appropriately stimulated to produce luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Due to this, the gonads do not produce sex hormones and do not function as expected.
Sometimes, a change (mutation) in the structure of luteinizing hormone leads to hypogonadism despite the pituitary gland and gonads being normal. In men, estrogen gives a negative feedback to block secretion of gonadotropin-releasing hormone. In some people, this feedback system might be defected. Stress-related hypogonadism can occur in women under physical or metabolic stress (such as with drastic weight loss or too much physical exercise). This also results in luteinizing hormone and follicle-stimulating hormone deficiency. Various chronic hypothalamic disorders can also be responsible.
Pituitary tumors, damaged blood vessels and inflammation of the pituitary gland can result in luteinizing hormone deficiency. Medical conditions such as pituitary tumors, an underactive thyroid gland, loss of kidney functions) and use of some medications (like anti-psychotics, metoclopramide, estrogen, anti-hypertensives, cimetidine) can also cause luteinizing hormone and follicle-stimulating hormone deficiency. In these instances the pituitary gland is affected from producing and secreting luteinizing hormone despite the hypothalamus being normal.
Luteinizing Hormone Deficiency Symptoms
The mains symptoms are the changes in reproductive health with difficulty falling pregnant and the development of secondary sexual characteristics,
- Delayed puberty
- Absence of menstruation in females
- No pubic, facial, or body hair in men
- No underarm (armpit) and pubic hair in women
- Underdevelopment of breasts in women
Hypogonadism has essentially the same symptoms but anosmia is absent. Sexual dysfunction in men and infertility in both men and women are noted in the adult years.
Luteinizing Hormone Deficiency Diagnosis
The symptoms alone can be attributed to many different causes of hypogonadism and related conditions. The following tests can be performed to diagnose luteinizing hormone deficiency.
- Lab tests: Blood samples are tested for levels of luteinizing hormone, thyroid-stimulating hormone (TSH), prolactin (PRL), estradiol, and follicle-stimulating hormone (FSH). Low luteinizing hormone/follicle-stimulating hormone and estradiol levels suggest a hypothalamic problem.
- Imaging studies: A magnetic resonance imaging (MRI) scan can detect a tumor or other abnormality in brain.
- Smell (olfactory) tests: These tests can be performed when Kallmann syndrome is suspected.
Luteinizing Hormone Deficiency Treatment
Treatment options can be directed at the hypogonadism on its own or the pituitary dysfunction. Luteinizing hormone deficiency when left untreated can lead to abnormal development of young individuals, infertility, and sexual dysfunction. Untreated luteinizing hormone deficiency and hypogonadism can also increase risk of osteoporosis and bone fractures.
Treatment for hypogonadism
- Estrogen is given to females with delayed puberty, which helps in developing secondary sexual traits like breast, pubic hair, and body shape.
- Gonadotropin injections are given to adult women to start ovulation.
- Progestins decrease the risk of endometrial cancer.
- Weight gain helps resume normal menses in women suffering from eating disorders.
- Testosterone is given to males with delayed puberty, which helps in restoring sex drive and in developing secondary sexual traits like pubic hair and masculinity.
- Gonadotropin-releasing hormone pump can deliver gonadotropin-releasing hormone under the skin in men.
- Gonadotropin-releasing hormone and clomiphene citrate treatment, both improve sexual function and sperm production.
Treating for pituitary dysfunction
- Dopamine agonists (like cabergoline, bromocriptine) block prolactin secretion and are given to males and females who desire fertility
- Oral contraceptives or estrogen and progestin are given to women to regulate menses.
- Surgery is done only in cases of pituitary tumors.
Luteinizing Hormone Deficiency Medication
- Patients with luteinizing hormone deficiency are given synthetic preparations of progestational agents or progesterone and ovulation induction agents (like clomiphene citrate).
- Androgens are given to treat hypogonadism.
- Testosterone develops and maintains secondary sex traits in androgen-deficient males.
- Estrogen derivatives are used as estrogen replacement therapy.
- Estradiol restores estrogen levels. Estrogen provides negative feedback, which the decreases release of gonadotropins from the hypothalamus. If estradiol is started within 10 years of menopause, it can prevent spine and hip bone fractures. Estradiol also promotes puberty.
- Ovulation induction agents (like follitropin alfa, clomiphene citrate) promote ovulation. Follitropin alfa promotes production of steroids from gonads. Clomiphene citrate is given orally to promote ovulation.