What is FSH hormone?

The article was consulted with Specialist Doctor II Pham Thi Tuyet Mai - Obstetrician and Gynecologist - Department of Obstetrics and Gynecology - Vinmec Hai Phong International General Hospital.

FSH is one of the most important sex hormones in the female body. FSH levels for each stage of the body will be different and sometimes even a sign of disease.

FSH (Folicle Stimulating Hormone) is a hormone released from the anterior pituitary gland in the brain. The female hormone FSH stimulates oocyte development and is part of the monthly menstrual cycle. Women with polycystic ovary syndrome (PCOS) often have low FSH levels, which causes failure to ovulate and leads to infertility. FSH hormone in men plays a role in stimulating the development of the seminiferous tubules and promoting sperm production.
If you suspect you have PCOS, your doctor will order you to perform a blood FSH measurement (usually in combination with other hormone tests) before making a diagnosis. Adult women typically have higher blood levels of FSH, which indicates ovarian maturation. Because at this time, a woman needs a large amount of hormones necessary for ovarian development and oocyte stimulation. So, what is FSH quantification and what does it mean?

During your menstrual cycle, FSH levels will not be stable but change to varying degrees. Doctors usually check this index by performing a blood FSH measurement on day 3 of the menstrual cycle. This is considered a baseline reference value (your normal FSH level), which ranges from 4.7 to 21.5 mIU/ml in menstruating women.
In fact, FSH is just one part of a very complex change of hormones in the body, including luteinizing hormone (LH), estradiol, and gonadotropin-releasing hormone (GnRH). FSH stimulates the development of immature oocytes. At the onset of development, the oocyte releases estradiol, which in turn acts on the hypothalamus and pituitary gland to increase the release of GnRH and LH, promoting ovulation. Before ovulation, FSH levels peak, stimulating the ovaries and causing ovulation. Once ovulation has occurred, FSH levels return to baseline or drop slightly below normal levels.

On the other hand, certain medications, such as birth control pills, clomiphene (used to treat infertility caused by anovulation), digitalis (a heart glycoside treatment for cardiovascular disease), and levodopa (used to treat Parkinson's disease), can make change the results of FSH quantification. Therefore, your doctor will usually direct you to stop taking those drugs before performing a blood FSH measurement. If you are taking hormonal birth control pills, you should stop using them and wait at least 4 weeks before having your FSH levels checked.
In general, FSH levels are closely related to ovulation. Women with very low FSH levels will not be able to ovulate. So, what is the chance of getting pregnant when getting the results of the FSH measurement in a female is too low?

Too low a female FSH is a sign of PCOS. Women with PCOS are unable to ovulate regularly and often lead to infertility. At this time, women really need advice and intervention from obstetricians or endocrinologists to get support about the possibility of pregnancy at the right time.
To solve this problem, doctors often use a form of the hormone FSH to stimulate the ovaries to produce oocytes for intrauterine insemination (or inject sperm into the uterus for fertilization - IUI) or in vitro fertilization (sperm and egg are cultured in a favorable environment, allowing fertilization to occur in vitro). These FSH hormones are given as an injection, commonly known as Gonal-f, Follistim, and Bravelle.
Many women often feel afraid when they have to inject drugs to stimulate ovulation. Although injection therapy can make women feel uncomfortable, more importantly, it helps PCOS patients regain the most sacred woman's right, which is the right to "motherhood." .

In women who want to have children, FSH levels are measured to check ovarian reserve - the number of eggs a woman has left and the quality of those eggs. Your doctor will perform a blood draw on the third day of your menstrual cycle. Quantitative FSH results are usually available within 24 hours depending on where the test is performed.
For women entering perimenopause, FSH levels begin to tend to increase. Because at this stage, the woman has a decrease in the response of the ovaries to the gonadotropic hormones FSH and LH, causing disturbances in the maturation of the oocytes. This will result in a woman getting her period but not ovulating, or ovulating with difficulty, irregularly, indicating a diminishing amount of remaining eggs.

Perimenopause lasts an average of 4 years and ends when a woman has not had a period for 12 months. After menopause begins, FSH levels are consistently elevated by 30 mIU/mL or more.
The presence of the hormone FSH in the body is extremely important for a woman's reproductive health. If you have never had an FSH measurement, you should talk to your doctor to do it once, to detect disorders related to the pituitary gland or ovaries, so that you can plan treatment in time.

References: Wikipedia.org; Verywellhealth.com