In men, LH stimulates testosterone production from the interstitial cells of the testes (Leydig cells). FSH stimulates testicular growth and enhances the production of an androgen-binding protein by the Sertoli cells, which are a component of the testicular tubule necessary for sustaining the maturing sperm cell.
LH controls the production of testosterone (T) by Leydig cells, the endocrine cells located in the interstitium of the testis (Figure 1A). T is essential for male virilization and, in combination with FSH, it triggers and maintains spermatogenesis.
In both males and females, FSH and LH are rhythmically secreted to control reproductive physiology. In males, these hormones drive the synthesis of testosterone and the production and development of sperm. In females, FSH triggers follicle maturation, and a sudden surge in LH drives ovulation.
Elevated LH and FSH levels suggest primary hypogonadism, whereas low or low-normal LH and FSH levels suggest secondary hypogonadism. Normal LH or FSH levels with low testosterone suggest primary defects in the hypothalamus and/or the pituitary (secondary hypogonadism).
If you are a man, high LH levels may mean: Your testicles have been damaged due to chemotherapy, radiation, infection, or alcohol abuse. You have Klinefelter's syndrome, a genetic disorder that affects sexual development in males. It often causes infertility.
Often, testosterone therapy is given to men with high FSH levels, since high FSH can lead to low testosterone; this can help increase fertility in these men. In other cases, treating the underlying cause of the abnormal FSH levels will correct the problem.
Usually, in healthy women, the ratio between LH and FSH usually lies between 1 and 2. In polycystic ovary disease women, this ratio becomes reversed, and it might reach as high as 2 or 3 (8). As a result of raised LH/FSH ratio, ovulation does not occur in polycystic ovary disease patients (9).
FSH and LH levels can help differentiate between a condition affecting the ovaries themselves (primary) and dysfunction of the ovaries due to disorders of either the pituitary or the hypothalamus (secondary). High levels of FSH and LH are consistent with conditions affecting the ovaries themselves.
In men, FSH helps control the production of sperm. Normally, FSH levels in men do not change very much. In children, FSH levels are usually low until puberty, when levels begin to rise.
High FSH levels in men may mean the testicles are not functioning correctly due to: Advancing age (male menopause) Damage to testicles caused by alcohol abuse, chemotherapy, or radiation. Problems with genes, such as Klinefelter syndrome. Treatment with hormones.
In men, LH primarily stimulates testosterone production, while FSH stimulates the production of sperm. The testes must be capable of response to this hormonal stimulus. In addition, there must be an intact ductal system to transport sperm to the urethra.
In males, where LH had also been called interstitial cell–stimulating hormone (ICSH), it stimulates Leydig cell production of testosterone.
LH stimulates Leydig cell T production, and FSH stimulates in Sertoli cells, in synergy with T, the production of regulatory molecules and nutrients needed for the maintenance of spermatogenesis. Hence, both T and FSH regulate spermatogenesis indirectly through Sertoli cells.
In men presenting with low FSH levels leading to secondary hypogonadism or high FSH levels resulting from primary hypogonadism, the history reveals erectile dysfunction, decreased libido, infertility, and low energy. In those with hyperprolactinemia, galactorrhea and/or gynecomastia may be present.
LH and FSH are the main regulating hormones of the hypothalamic-pituitary-gonadal axis, and their deficiency can present as delayed puberty, reproductive abnormalities, and hypogonadism depending on whether the condition occurs before or after puberty.
Malfunction of the pituitary gland
The pituitary gland produces and secretes FSH and LH. The ovaries cannot ovulate properly if too much or too little of these hormones is produced. The pituitary gland may not function properly due to physical injury, a tumor or a chemical imbalance in the pituitary gland.
Luteinizing hormone (LH) plays a key role in gonadal function. LH in synergy with follicle stimulating hormone (FSH) stimulates follicular growth and ovulation. Thus, normal follicular growth is the result of complementary action of FSH and LH.
Now results published in The New England Journal of Medicine and Cell Metabolism have revealed the rise in FSH at the time of the menopause may be responsible for the waist-thickening weight gain.
FSH reflects the status of spermatogenesis (i.e. the ability to produce sperm) as a result of the feedback between the testis and hypothalamus/pituitary glands. An elevated FSH level is indicative of abnormal spermatogenesis and may indicate primary testicular failure.
In men presenting with high FSH levels due to a gonadotroph adenoma, symptoms result from the mass effect (eg, headaches, visual impairment, hormonal deficiencies). However, erectile dysfunction and infertility may occur secondary to low LH levels caused by compression of the normal gonadotroph cells.
In both sexes, LH contributes to the maturation of primordial germ cells. In men, LH causes the Leydig cells of the testes to produce testosterone. In women, LH triggers the creation of steroid hormones from the ovaries [1].
A high or low LH level isn't simply good or bad. For instance, a surge in your LH can show that you're about to ovulate. You're most likely to become pregnant at this time. This information that LH provides about your fertility is helpful if you're trying to have a baby.