FSH Levels: Follicle-Stimulating Hormone Function in Fertility

What is Follicle-Stimulating Hormone (FSH)?

Follicle-stimulating hormone (FSH) is an essential reproductive hormone in both sexes. It is a glycoprotein (proteins that play a crucial role in different physiological functions in the body) produced by the anterior pituitary gland (a gland in your brain that controls your hormonal functions). It plays a significant role in an individual's sexual development and reproduction. The two essential hormones, Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH), together classified as GONADOTROPTHINS, are integral factors in fertilisation in both males and females. 

What is the Function of Follicle-Stimulating Hormone (FSH)?

In women, follicle-stimulating hormone (FSH) regulates the menstrual cycle and ovulation; FSH promotes growth, maturation and breakage of the ovarian follicle (an entity that contains female eggs until ovulation). The FSH level rises during the start of the menstrual cycle and helps develop ovarian follicles. 

When the follicles mature, they produce estradiol, which triggers ovulation on the 14th day. 

This triggers ovulation on the 14th day, leading to the breakage of the follicle and the release of a mature egg from the broken follicle.

In females, this hormone helps in

• Regulation of menstrual cycle.
• Follicular Development.
• Ovulation.

In males, FSH promotes spermatogenesis (sperm production) by acting on Sertoli cells. It also stimulates the secretion of androgen-binding proteins, which sustain spermatogenesis.

It not only produces sperm but also interacts with other hormones (LH) and stimulates testosterone production from Leydig cells. This Hormonal interaction is pivotal for the male reproduction process.

So, in males, it helps in 

• Sperm production (spermatogenesis).
• Hormonal interaction to produce testosterone.

FSH levels fluctuate in both sexes throughout life due to various factors such as age and hormonal feedback mechanisms from the ovaries and testes

Normal vs. Abnormal FSH Levels

Normal levels of follicle-stimulating hormone (FSH) vary by age and sex. 

• The normal level for women is between 4.7 and 21.5 mIU/mL during menstruation. It may rise to 25.8 to 134.8 mIU/mL after menopause. 
• For adult men, the normal level is between 1.4 to 15.4 mIU/mL.

An abnormal FSH level is either high or low, outside the range mentioned above. It is indicative of various health issues.

What Do High and Low FSH Levels Indicate?

1. Abnormal FSH in women

• In women, high levels usually suggest menopause if she is approaching the menopausal age. 
• In young women, it is indicative of ovarian insufficiency, ovarian failure, diminished ovarian reserve,  low-quality eggs, PCOS, and elevated FSH, which is also seen in conditions like Turner's syndrome and ovarian tumours. 
• Low levels indicate hypogonadism (low production of sex hormones by ovaries) or inadequate functioning of ovaries. 
• Low levels of FSH are also seen in underweight conditions.

2. Abnormal FSH in men

• In men, high FSH is indicative of testicular dysfunction or damage. Elevated FSH is also seen in conditions like Klinefelter syndrome.
• Low levels are indicative of pituitary or hypothalamic disorders or elevated testosterone, which in turn suppresses further production of FSH. 
• Low levels also reflect in some cases of extreme stress or those with eating disorders.

Impact on Fertility and Reproductive Health

• Both High levels and low levels of FSH pose significant impacts on reproductive health and infertility in both males and females.
• In women, High levels of FSH are because of diminished ovarian reserve and overall reproductive health. This results in achieving pregnancy naturally.
• Low FSH levels in women lead to improper development and maturation of ovarian follicles, which in turn leads to low egg quality and quantity, which can make the process of conception harder. 
• In addition to that, menstrual cycles will be irregular in some women. In some others, it may even be absent. 
• Low FSH also leads to delayed onset of puberty and other development issues in adolescent girls approaching puberty. 
• A low FSH leads to low libido and hot flashes.
• Abnormal FSH in males also pose difficulties leading to infertility as FSH controls the spermatogenesis process itself, leading to a lack of production of enough sperm from Sertoli cells for fertilisation.
• A complete lack of FSH in males leads to no sperm production (azoospermia), whereas a partial deficiency reduces sperm count, sperm motility, and so on. In young males, it may lead to a delay in puberty or incomplete puberty, along with inadequate sexual development. All of these factors result in infertility.

Testing FSH Levels

The FSH test is a tool for diagnosing reproductive health issues in both genders. It can even understand hormonal balance. The results usually take one or two days. The FSH test is not confirmative of complete ovarian failure or infertility.

FSH testing is often done to:

• Evaluate fertility issues in both genders.
• Diagnose issues related to improper ovarian or testicular function.
• Monitor hormone levels during puberty, menopause and other phases of menstrual cycle.

As FSH is more prone to fluctuation, its levels are usually measured on the second or third day of the menstrual cycle for precision in values in women.  Abnormal FSH readings may prompt further investigation to check ovarian function and overall reproductive health. 

To test Follicle follicle-stimulating hormone (FSH) levels, doctors usually suggest blood tests or urine tests.

Normal Ranges for FSH Blood Test 

Women

• Follicular Phase - 1.4 to 9.9 mIU/mL
• Ovulatory Peak - 6.2 to 17.2 mIU/mL
• Luteal Phase- 1.1 to 9.2 mIU/mL
• Post-Menopause- 25.8 to 134.8 mIU/mL

Men

• Normal range: 1.4 to 15.4 mIU/mL  

Children

• Normal levels can vary but are generally up to 2.5 mIU/mL

Urine Test Results for FSH

FSH urine tests are not commonly done.  Both urine and blood tests measure the level of FSH, but they do not share the same normal ranges, and the testing context plays an essential role in interpreting the results.  

Even though urine tests reflect a similar pattern as blood tests, the reference ranges vary as they are not as standardised as blood tests. Blood tests predict fluctuation more precisely than urine tests.

Abnormal levels of FSH can be indicative of infertility, hormonal imbalances, or issues in the functioning of the pituitary gland.

If you are concerned about your FSH test result, discuss it with a doctor so that further testing can be conducted to properly interpret it.

What Triggers FSH Production?

The pituitary gland's production of FSH is primarily triggered by yet another hormone, gonadotropin-releasing hormone (GnRH). 

GnRH promotes the production of two hormones: follicle-stimulating hormone (FSH) and luteinising hormone (LH), known as gonadotropins.

In females, Follicle follicle-stimulating hormone promotes the growth and development of ovarian follicles. It also stimulates the production of estradiol. Increased estradiol production from developing ovarian follicles suppresses FSH secretion by inhibiting the production of Gonadotropin-Releasing Hormone (GnRH) from the hypothalamus through a negative feedback mechanism.

In males, FSH promotes spermatogenesis via Sertoli cells.  Sertoli cells produce a glycoprotein called Inhibin B. When inhibin B levels rise, it signals the anterior pituitary to reduce the secretion of follicle-stimulating hormone by a negative feedback mechanism. This ensures a balanced sperm production and homeostasis of overall reproductive health.   

What is the Normal FSH Level for Pregnancy?

• The normal level of follicle-stimulating hormone (FSH) for women during the early menstrual cycle (on Day 3 of the cycle) typically ranges from 5 to 20 IU/L (international units per litre). 
• The optimal FSH Level for natural conception is generally up to 10 mIU/mL, mainly measured on day 3 of the menstrual cycle. This value indicates a healthy ovarian reserve and a higher chance of conception. 
• Levels above 15 IU/L suggest diminished ovarian reserve or conditions like premature ovarian insufficiency and lower fertility potential. Lower FSH levels are favourable for conception.
• FSH levels reduce significantly during the first phase of pregnancy. It comes to around 0.1 IU/L during 28 to 30 days after ovulation). This reduction is indicative of the body's hormonal balance, which supports pregnancy and the development of the foetus. 

FSH levels can vary based on age and individual hormonal balance, so before planning for conception or if you find it difficult to conceive, consult a doctor to evaluate essential parameters like FSH.

What are the Symptoms of Abnormal FSH Levels?

The body exhibits various symptoms when the FSH level goes above and below an optimum range.

Usually, high FSH levels indicate menopause in normal cases. Some disease conditions like PCOS, ovarian insufficiency or dysfunction may also go high. High FSH usually manifests as menopausal symptoms, which include:

• Irregular or absent menstrual periods.
• Hot flashes.
• Night sweats.
• Difficulty to sleep.
• Vaginal dryness.
• Lower sex drive.
• Mood swings.

Conversely, low FSH levels reflect underlying imbalances of sex hormones or the complex functioning of ovaries. It results in symptoms like:

• Fatigue.
• Infertility/ Difficulty conceiving.
• Low libido or decreased sexual drive.

The symptoms mentioned above suggest the necessity of hormonal evaluation.

Wrapping It Up

If you experience the symptoms mentioned above or your FSH test result is abnormally high or low, consult a doctor or health care provider to interpret the result accurately. They may suggest additional tests like LH and estradiol to get a better and more precise picture of the situation. 

After assessing your reproductive health and infertility concerns are noticed, they may recommend fertility options based on the necessity. 

Sometimes, a trivial Lifestyle change or diet modification may be enough. Others may need psychological support, such as counselling or stress reduction techniques. The doctor at Nirva Health can carefully evaluate your symptoms and tailor management options.