All about FSH hormone: How does it affect your fertility? (Follicle-Stimulating Hormone - FSH)

You've probably heard the word "hormones" a lot, right? These hormones control many things in our bodies, such as emotions, growth, sleep, and hunger. So, today we're going to talk about a special hormone that is very important for sexual development and the ability to have children, that is, fertility. That hormone is FSH, or Follicle-Stimulating Hormone. Although the name may seem a bit complicated, its function is very simple to understand.

Simply put, what is FSH?

FSH is a hormone produced by the pituitary gland, a small gland in our brain. Its main function is to control the function of the ovaries in women and the testicles in men.

When you hear the name, some might think that this is something related to hair follicles. But it is not. Another group of hormones called androgens affects hair growth. FSH gets its name because it stimulates small fluid-filled sacs called ovarian follicles in women's ovaries. These follicles contain eggs.

What are the functions of the FSH hormone?

The FSH hormone is important in different ways at different stages of our lives. Let's see how.

For the development of the baby in the womb

Surprisingly, during the second and third trimesters of pregnancy, from about 13 weeks until delivery, the fetus's pituitary gland also begins to produce hormones called FSH and LH (Luteinizing Hormone). These hormone levels peak around mid-pregnancy, as the fetus's first ovarian follicle or seminiferous tubule matures.

During puberty

During childhood, FSH levels are usually very low. However, as puberty approaches, usually between the ages of 10 and 14, the hypothalamus in the brain produces a hormone called GnRH (Gonadotropin-releasing hormone). This GnRH signals the pituitary gland to start producing FSH and LH. This is when sexual maturation and the related physical changes begin.

• Boys: FSH and LH work together to stimulate the testicles to produce testosterone . This hormone is responsible for changes in boys during puberty, such as body hair growth, deepening of the voice, and the production of sperm.
• In girls: FSH and LH work together to stimulate the ovaries to produce the hormone estrogen . This hormone is responsible for breast development and the onset of menstruation .

Menstruating women

The main function of the FSH hormone is to regulate the menstrual cycle of a woman who is menstruating. Simply put, FSH stimulates the growth of follicles in the ovaries, preparing the eggs for ovulation. As these follicles grow, they release estrogen and small amounts of progesterone into the blood.

Between days 6 and 14 of the menstrual cycle, FSH causes several follicles in an ovary to begin to mature. But by days 10-14, only one of these follicles has developed into a fully mature egg. Around day 14, there is a sudden surge in the hormone LH. This causes the fully mature follicle to burst and release the egg. This is what we call ovulation .

After ovulation, the ruptured follicle becomes a temporary gland called the corpus luteum, which produces large amounts of the hormone progesterone. This progesterone stops the production of FSH and prepares the uterine wall for pregnancy.

Men's

The main function of the male hormone FSH is to stimulate sperm production . FSH also helps maintain sperm production by working with testosterone, which is produced by LH.

How is FSH production controlled?

This is a rather complex control system. It's like the way a big company works. We call it the hypothalamic-pituitary-gonadal axis. The parts of the brain (hypothalamus, pituitary gland) and the gonads (ovaries/testicles) in this system are constantly communicating with each other.

1. Beginning: First, the hypothalamus produces a hormone called GnRH.

2. Stimulation: This GnRH goes to the pituitary gland and tells it to produce the hormones FSH and LH.

3. Action: FSH and LH, produced by the pituitary gland, travel through the blood and bind to the ovaries or testicles (gonads) to control their function.

4. Feedback: Then, hormones produced by the ovaries and testicles (such as estrogen and testosterone) send signals back to the brain to tell it how much GnRH, FSH, and LH to produce. This continues in a cycle.

If there is a slight malfunction anywhere in this system, the entire hormonal balance can be disrupted.

What are normal FSH levels like?

Normal levels of FSH vary depending on age, gender, and the day of the menstrual cycle in women. Importantly, the normal range can vary slightly between labs. Therefore, it is important to compare your results with the lab's normal range on your report. If you have any questions about your results, be sure to talk to your doctor.

Below are the generally accepted values. The unit of measurement is mIU/mL (milli-international units per milliliter).

Is there an appropriate FSH level for pregnancy?

This is a very important question for couples hoping to have children. Measuring FSH levels is essential when testing for fertility. The best time to do this test is on day 3 of the menstrual cycle (the first day of menstruation is considered day 1).

A study of the results of IVF (In Vitro Fertilization) treatments showed that those with FSH levels below 15 mIU/mL on day 3 had a higher chance of pregnancy than those with FSH levels between 15 and 24.9. Those with FSH levels above 25 had an even lower chance of pregnancy.

What does an elevated FSH level mean?

In most cases, if FSH levels are higher than normal, it means there is a problem with the ovaries or testicles .

Imagine that the ovaries or testicles are not making enough estrogen or testosterone. Then, the pituitary gland in the brain realizes this and thinks, "Okay, I need to send more FSH to make these things work," and it releases a lot of FSH into the blood. But because of a problem with the gonads, they are unable to respond properly to the amount of FSH that is coming in. We call this condition primary hypogonadism . The following can cause this:

• Birth defects:
• Klinefelter syndrome in men
• Turner syndrome in women
• Subsequent causes:
• Radiation or chemotherapy for cancer
• Injuries to the ovaries or testicles
• Declining hormone levels with aging
• Some autoimmune conditions
• Infections such as mumps

Also, women's FSH levels naturally increase during menopause . This is normal. If children's FSH levels are higher than their age and sexual characteristics are developing, it may be a sign of precocious puberty .

What does a low FSH level mean?

If FSH levels are lower than normal, it often indicates a problem with the pituitary gland or hypothalamus . Because the brain is not signaling the production of FSH, the ovaries or testicles do not function properly. This condition is called hypogonadotropic-hypogonadism .

This may be due to:

• Pituitary gland problems: Things like pituitary adenomas can cause the gland to become compressed or damaged, which can disrupt hormone production.
• Hypothalamic problems: Rare genetic conditions such as Kallmann syndrome can cause decreased production of the hormone GnRH, which can lead to decreased FSH levels.

What are the symptoms of abnormal FSH levels?

Whether FSH levels are low or high, the symptoms often resemble those of hypogonadism , i.e., underactive gonads. These symptoms vary by age and gender.

How are FSH levels measured?

Your FSH level can be measured with a simple blood test . Along with this test, your doctor may recommend several other hormone tests to get a complete picture of your condition.

• Luteinizing hormone (LH)
• Testosterone
• Estradiol and/or progesterone

These tests are usually done:

• To find the cause of infertility
• To diagnose problems with the ovaries or testicles
• To diagnose problems with the pituitary gland or hypothalamus
• To find the causes of irregular menstruation
• To know if menopause is approaching
• To find the causes of low sperm count
• To find out the reasons why puberty in children is delayed or early.

When should I see a doctor?

If you or your child has one or more of the following conditions, it is very important to see a doctor for advice.

• If you have the symptoms of hypogonadism mentioned above (such as decreased sexual desire, excessive fatigue, infertility).
• If your child is entering puberty earlier or later than normal .
• If you are expecting a baby but are having difficulty getting pregnant .

FSH is a hormone that is essential for sexual development and fertility in our body. Because it is intricately linked to many other hormones, sometimes its levels can be abnormal. But don't worry about it. If you think you or your child has a problem with this, talk to a doctor. They are always ready to help you.