n., plural: follicle-stimulating hormones
[ˈfɒlɪk(ə)l ˈstɪmjʊˌleɪtɪŋ ˈhɔːməʊn]
Definition: A gonadotropin released by the gonadotropic cells of the anterior pituitary, primarily for the growth of ovarial follicles and spermatogenesis
Follicle Stimulating Hormone Definition
In the pituitary gland of the brain, gonadotropic hormones are released. Gonadotropins are responsible for regulating the ovaries. One type of gonadotropin is the luteinizing hormone (LH), while the other is the follicle-stimulating hormone (FSH). Recombinant follicle stimulating hormone is gonadotropin. The follicle stimulating hormone location is the pituitary gland which secretes it. This promotes the formation of follicles carrying the eggs in the ovaries. The granulosa cells that surround the follicle are stimulated by FSH to produce estrogen, which is an essential hormone for not only regulating the menstrual cycle but also for the development of the ovarian follicles.
Define follicle stimulating hormone
The follicle stimulating hormone (FSH) is a glycoprotein hormone with a molecular weight of approximately 30,000. FSH is secreted from the pituitary gland and acts on the follicular cells in the ovaries. The pituitary gland secretes FSH in the morning and collects it in the evening. FSH is a glycoprotein hormone.
What is follicle stimulating hormone or what is FSH hormone?
Both luteinizing hormone and follicle-stimulating hormone are gonadotropic hormones. When it comes to pubertal development and ovulation, follicle-stimulating hormone (FSH) is a key player. This hormone facilitates the growth of ovarian follicle cells in the ovary, where one egg is produced from a single follicle, before ovulation. It also boosts the production of estradiol. The FSH in males stimulates the Sertoli cells in the testes, a hormone produced by the ovaries (spermatogenesis). (Endocrinology, 2018)
The follicle-stimulating hormone is a gonadotropin produced and released by the gonadotropic cells. The gonadotropic cells are one of the many endocrine cell types in the anterior pituitary. Apart from this hormone, these cells release luteinizing hormone (LH) as well. The follicle-stimulating hormone (FSH) is an acidic glycoprotein hormone made up of two polypeptide units: alpha and beta whereas the glycan subunit includes N-acetylgalactosmine, mannose, N-acetylglucosamine, galactose, and sialic acid. This glycan portion of the hormone bonds covalently with asparagine.
The polypeptide and the glycan components are essential for FSH to function. It works in synergy with LH. In general, FSH is responsible for the regulation of development, growth, pubertal maturation, and reproductive processes. In women, FSH stimulates the development of ovarian follicles (eggs) and stimulates the release of estrogens. In men, FSH stimulates the production of sperm. It induces the Sertoli cells to secrete androgen-binding proteins. Abnormal FSH levels may be seen in the following conditions: hypopituitarism, Klinefelter syndrome, polycystic ovary disease, Turners syndrome, and ovarian failure.
What does the FSH hormone do?
Follicle-stimulating hormone serves two functions:
1. synthesis of estrogen
2. follicular growth
Synthesis of estrogen
The regulation of the menstrual cycle and the health of the reproductive system depending on LH, FSH, and Estrogen. The follicle-stimulating hormone travels to the ovaries, where it interacts with granulosa cells to generate an enzyme known as aromatase, which then turns adjacent cell-released androgens (testosterone) into an estrogen known as estradiol.
What hormone triggers ovulation? Immature eggs develop in the ovaries. Each month, in response to hormones in the body, the most mature egg is released from the ovary into the fallopian tube in a process known as ovulation. One main hormone that has a role in maturation is the Follicle-stimulating hormone.
When follicle stimulating hormone levels (FSH follicular phase) rise early in the menstrual cycle, more Estradiol is produced, which has a negative feedback on Follicle-stimulating hormone levels. To put it another way, when a lot of Estradiol is present, it instructs the brain region, that released the FSH, to stop.
How is follicle stimulating hormone controlled?
Follicle stimulating hormone structure is related to that of human chorionic gonadotropin (hCG), luteinizing hormone (LH) and thyroid stimulating hormone (TSH). The secretion and production of follicle stimulating hormones are regulated by circulating hormones which are realized in testes and ovaries.
The name of the system is known as the hypothalamic-pituitary-gonadal axis. Ovulation is triggered by the gonadotropin hormone. Hypothalamus released gonadotropin hormone. It gets attached to the receptor site of the anterior pituitary. It is responsible not only for release but also for the synthesis of luteinizing and follicle stimulating hormones.
These follicle stimulating hormones go into the blood and get attached to the receptors of the ovaries and testes. The function of ovaries and testes is regulated and maintained by luteinizing and follicle stimulating hormones.
The longest period of the menstrual cycle is the follicular phase. It begins from day one and lasts until ovulation.
The nerve cells present in the hypothalamus detect the reduction in hormone levels at the end of the menstrual cycle in females. The production of gonadotropin hormone increases by nerve cells, which also causes the concentration of follicle stimulating hormone and luteinizing hormone to increase in the blood.
The number of follicles in the ovary also starts to increase due to the increase in the level of follicle stimulating hormone. The level of inhibin and Estradiol also increases with the increase in the growth of follicles. After this, the pituitary gland and hypothalamus detect the level of these hormones. So, the minimum level of follicle stimulating hormone and gonadotropin hormone is released.
Although, due to the increase in the follicles the level of estrogen also increases. It causes to increase in the level of follicle stimulating hormone as well as luteinizing hormone. In the female FSH stimulates the hormones that are responsible for the discharge of an egg from a mature follicle. This process is called ovulation. 6-10 follicles are normal. Follicle stimulating hormone treatment is used to treat infertility in females.
What is a normal FSH level??
FSH blood test or follicle stimulating hormone serum is used to find the range of FSH. The normal FSH range/level in females and males by age is shown in the following FSH levels chart.
FSH Levels Chart
|Prior to adolescence||0-5 mIU/mL||0-4 mIU/mL|
|During adolescence||0.3-10 mIU/mL||0.3-10 mIU/mL|
|Adult male/menstruating female||1.5-12.4 mIU/mL||4.7-21.5 mIU/mL|
|FSH level in menopause||25.8-134.8 mIU/mL|
|FSH normal range and LH levels by age:|
|20 to 70 years||0.7-7.9 IU/L|
|After 70 years||3.1-34.0 IU/L|
|The follicular phase of female||1.9-12.5 IU/L|
|Expecting female||<1.5 IU/L|
|Post-menopausal female||15.9-54.0 IU/L H2|
Data Source: Shoaib Zaheer of Biology Online.
What Do High FSH Levels Mean?
High FSH levels can indicate a variety of issues. When the number of immature follicles left in the ovary is low, more FSH is produced to effectively mature an egg, each month, for ovulation. When the number of eggs reduces, the level of Estradiol also reduces so the brain no longer receives the negative feedback that urges it to create less FSH. Because a high follicle stimulating hormone level shows that ovaries are not performing normally, it is usually used to assess whether a woman is approaching menopause or has reached the end of her capacity to ovulate. High FSH levels in women cause loss of ovaries function or primary ovarian insufficiency POI.
Turner syndrome, a hereditary condition that affects sexual development, is also associated with high FSH levels. High FSH levels can also predict ovarian cancer in some patients, however, this is extremely unusual.
Irregular periods, Disrupted sleep, Hot flashes, Difficulty getting pregnant and Skin and hair changes are high FSH levels symptoms.
What are considered high FSH levels? FSH level above 25 mIU/mL indicates fewer eggs. FSH perimenopause level is > 30 IU/L.
FSH levels can be raised as a result of dietary and lifestyle factors, and changes in these areas may help to lower them. It’s crucial to note that if elevated FSH levels are the result of menopause, dietary or lifestyle changes will not be able to undo the situation.
Smoking, excessive alcohol consumption, vitamin D insufficiency, and polychlorinated biphenyls are all factors that contribute to increasing follicle stimulating hormone. (Limited, 2022)
What Do Low FSH Levels Mean?
Low level of FSH means that ovaries are not producing adequate eggs or the pituitary gland (which creates FSH) is malfunctioning. When it comes to the pituitary gland, either the gland itself or the hypothalamus might be the source of the problem. Low FSH levels might also be caused by a lack of energy.
Flashes of heat, hair loss in the pubic area, lack of milk production while nursing, and irregular or no periods are low FSH levels symptoms.
People who are very underweight or who work out often are more likely to have this condition, which happens when they exhaust more calories than they take in. Low FSH levels may also be induced by a glucocorticoid, high-soy- or isoflavone-containing diet, extreme exercise, eating disorders, or a recent meningitis infection.
What FSH Level Indicates Menopause
Menopause is a natural biological process, but between the ages of 40 and 60, the woman’s reproductive system can no longer respond to her menstrual cycle. The follicular cells are no longer produced, and the production of oocytes is stopped. A woman who is in her forties or fifties has completed menopause and can no longer bear children. FSH level of 1.9-12.5 IU/L is an indication of menopause.
Try to answer the quiz below to check what you have learned so far about follicle-stimulating hormones.
- Cascocup.com. (2021). Follicular Phase. Retrieved 9 April, 2022, from https://www.cascocup.com/blogs/health/follicular-phase#:~:text=The%20follicular%20phase%20is%20the,between%2011%20and%2027%20days.
- Yourhormones.info. (2018). Alternative names for follicle-stimulating hormone. Retrieved 9 April, 2022, from https://www.yourhormones.info/hormones/follicle-stimulating-hormone/
- Fertilityfamily.co.uk. (2022). Follicle-stimulating hormone treatment Retrieved 09 April, 2022, from https://www.fertilityfamily.co.uk/blog/how-many-eggs-per-follicle-everything-you-need-to-know/#:~:text=The%20number%20of%20antral%20follicles,reserve%20is%20greater%20than%2012.
- Follicle-Stimulating Hormone. (2022). Retrieved 09 April, 2022, from https://hertilityhealth.com/blog/what-do-your-fsh-levels-mean/
- LastChecked.com (2022a). high FSH levels symptoms. Retrieved 9 April, 2022, from https://www.letsgetchecked.com/articles/what-are-the-symptoms-of-high-fsh-in-women/
- LastChecked.com (2022b). Low FSH: Symptoms and Causes. Retrieved 9 April, 2022, from https://www.letsgetchecked.com/articles/what-are-the-symptoms-of-low-fsh-in-women/
- Luteinizing hormone. (2022). Retrieved 9 April, 2022, from https://www.healthline.com/health/lh-blood-test#outlook
- Menopause Transition. (2022). Retrieved 9 April, 2022, from https://www.med.upenn.edu/womenswellness/menopause.html#:~:text=An%20FSH%20level%20of%20%3E%2030,presence%20of%20common%20menopausal%20symptoms
- Mountsinai.org. (2022). normal FSH level. Retrieved 9 April, 2022, from https://www.mountsinai.org/health-library/tests/follicle-stimulating-hormone-fsh-blood-test#:~:text=Normal%20Results&text=Before%20puberty%3A%200%20to%205.0,1.5%20to%2012.4%20IU%2FL)
©BiologyOnline.com. Content provided and moderated by Biology Online Editors.