Luteinizing Hormone LH is another important hormone for reproduction. In men, LH promotes secretion of testosterone. In women, LH surge in the second part of the menstrual cycle triggers ovulation. LH is released when a woman is ovulating, and causes the ovaries to release an egg. LH and FSH are closely linked. At the beginning of the menstrual cycle, FSH and LH are secreted to stimulate ovarian follicles. Mid-cycle, the growing follicle will inhibit FSH secretion and increase estrogen. This is a trigger for sudden release of LH that leads to release of the mature egg.
The LH Surge is vital for pregnancy - as it causes the matured egg to be released. The next 24 - 36 hours are the fertile window when a woman can get pregnant. Ovulation Predictor Kits that are available measure LH level in the urine - identifying the best time to conceive. Reduced levels of LH in females indicate ovarian hyperfunction.
LH and PCOS
In females suffering from PCOS - Polycystic Ovarian Syndrome, the LH levels are already elevated when compared to FSH. Since there is no LH surge, ovulation does not take place. Elevated LH levels cause release of androgens from the ovaries leading to acne and Hirsutism. Infertility and miscarriage are common. Studies have shown that there is a direct relation between insulin resistance and elevated LH levels.
In females, the LH levels in the blood can vary based on stage of menstrual cycle, age, pregnancy and other pituitary gland disorders. It can be measured by a blood test or urine test. Usually this test is prescribed for women with irregular periods trying to get pregnant or assessing if a woman has entered menopause. Men with low testosterone levels or having very late puberty are asked to take the LH test.
High levels of Luteinizing hormone are most often caused by ovarian tumors or improperly-developed ovaries. Thyroid or Adrenal disease can elevate LH levels. PCOS and Autoimmune disorders also cause the levels of Luteinizing hormone to rise. Low levels of Luteinizing hormone indicate ovarian failure or primary testicular failure. This can happen due to viral infections such as mumps, autoimmune disorders, radiation exposure and tumors.
Early phase of menstrual cycle: 0.5 to 16.9 IU/L
Peak of menstrual cycle: 8.7 to 76.3 IU/L
Using contraceptives: 0.7 to 5.6 IU/L
Pregnant: less than 1.5 IU/L
Menopause: 15.9 to 54.0 IU/L
Between 20 years and 70 years: 0.7 to 7.9 IU/L
Over 70 years: 3.1 to 34.0 IU/L
Gonadotropin-releasing hormone (GnRH) is a neurohormone consisting of ten amino acids which is produced by the arcuate nuclei of the hypothalamus. It is integral for starting the reproductive hormone cascade.
GnRH is secreted in the hypothalamus which is part of the brain. The hypothalamus is part of the 'Hypothalamus - Pituitary - Gonad' axis which regulates the reproductive system in men and women. Secretion of GnRH by the hypothalamus is delivered through a direct pathway between the hypothalamus and pituitary. GnRH stimulates the synthesis and secretion of two gonadotrophins namely, lutenizing hormone (LH) and follicle stimulating hormone (FSH) by the anterior pituitary gland. Controlled by internal and external factors, GnRH acts in a negative feedback loop. For instance, if there is excess FSH, LH or testosterone, then these hormones will inhibit GnRH production.
Lifestyles can also affect GnRH secretion. Lack of exercise, poor diet, opiad drugs and excessive stress can negatively affect GnRH production. What is so striking in GnRH is that under normal circumstances, GnRH is released at intervals of 90 to 120 minutes. Hence, in patients with GnRH deficiency, the releasing hormone should be administered in pulses. Constant administration of GnRH also suppresses gonadotropin secretion especially in children in puberty stage and in men with prostate cancer.
Why is GnRH treatment used?
This hormone is produced by the hypothalamus and it stimulates the pituitary gland to produce LH and FSH. Lack of GnRH in the hypothalamus can halt testosterone production in the testicles of men. In women, abnormal GnRH levels can be responsible for ovulatory disorders.
This is commonly used when Clomid treatment has not stimulated egg follicles to develop on the ovaries. GnRH works effectively to replace the natural GnRH in women and men who do not produce enough of it. Failure of release of GnRH can result in deficiency that can be partial or complete.
In a woman who is not ovulating because of lack of stimulation from hypothalamus.
In a man who is not producing sperm because his hypothalamus is not stimulating the hormones that trigger sperm production.
The use of GnRH can result in multiple pregnancies.
Some studies report that the pregnancy rate after treatment with GnRH is about 20%.
Some side effects include:
The small pump that is used for GnRH may bother some people and treatment requires daily monitoring by a doctor.
Although clinicians and scientists have observed the findings of olfactory disturbances and reproductive dysfunction, the syndrome comprising complete GnRH deficiency and lack of olfactory senses is named Kallmann Syndrome after the American geneticist Kallmann who identified this disorder in 1944.
The choice of therapy depends upon the patient's desire to achieve one or more of the following options:
In males, treatment is decided to provide androgen replacement. The patient's age, potential adverse effects of therapy, patient's desire for fertility are considered. In the prepubertal male, GnRH stimulates penile growth, body and facial hair growth, bone and muscle development and voice changes. Androgens also stimulate growth hormone production, contributing to the adolescent growth spurt. Male androgen deficiency can result in social ridicule and therefore starting androgen therapy around age 14-15 is prudent.
Oral, injectable and transdermal and implantable pellets formulation are available for treatment of males with Kallmann syndrome. Oral androgen preparations should not be used due to their toxic effects on the liver and adverse effects on lipids. Injectable long-acting testosterone are low-cost, relatively safe and effective. The disadvantages include intramuscular injection and non physiologic pattern of testosterone over the dosing interval. There could be wide swings in libido in some men.
Transdermal patches and gel preparation of testosterone are currently available - adverse effect with these formulations include skin reactions at the application. In females as in males, treatment depends upon age and fertility desires. Estrogen replacement is a must to prevent osteoporosis.
Oral preparations, transdermal patches, vaginal cream and rings are available for standard hormone replacement therapy. Transdermally administered 17 beta estradiol has been shown as an effective regimen for preventing bone loss in normal menopausal women.
Women with intact uterus receive a cyclical progestin to accompany estradiol treatment. Optimal hormone therapy depends upon whether the patient has primary or secondary amenorrhea. Gradual dose escalation results in optimal breast development and allows time for young woman to adjust psychologically to her physical maturation.
Anovulation indicates a situation where a woman is unable to get pregnant as there is no release of ripened egg from the ovaries. While often a woman might have her menstrual periods, ovulation may not be taking place. Often anovulation is a major cause for infertility in women. Anovulation can occur due to stress, reaction from drugs, over-exercising or problems in endocrine system such as progesterone imbalance, congenital adrenal hyperplasia or ovarian failure. Other causes include excessive weight gain, anorexia or bulimia. A woman suffering from PCOS is also likely to suffer to anovulation. Symptoms of anovulation include amenorrhea, absence of PMS symptoms and hirsutism.
Various tests such as Thyroidfunction test, Adrenal function test, LH and FSH tests and prolactin test are conducted to check for possible causes of anovulation. It may be accompanied by pelvic ultrasound, CAT scan and MRI. Treatment with fertility drugs usually solves the problem of anovulation. These include Clomiphene, Gonadotropin and Pergonal. The woman is required to maintain good body weight with right diet and exercise.Tags: #LH #GnRH #Anovulation
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Collection of Pages - Last revised Date: March 8, 2021