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FSH: Function, Tests, High & Low Levels + How to Normalize It

Written by Carlos Tello, PhD (Molecular Biology) | Last updated:
Puya Yazdi
Medically reviewed by
Puya Yazdi, MD | Written by Carlos Tello, PhD (Molecular Biology) | Last updated:

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FSH and reproductive health

Follicle-stimulating hormone (FSH) is a hormone produced by the pituitary gland. This hormone is vital to growth and development during puberty, as well as reproductive function. Read below to learn more about its functions.

What Is Follicle-Stimulating Hormone?

Follicle-stimulating hormone (FSH) is a gonadotropic hormone secreted by the pituitary gland. FSH is important for growth and development during puberty and to control the function of reproductive organs [1].

Function In Men

In men, FSH acts on the testes to stimulate sperm production. This hormone promotes testicular growth and aids in the production of androgen-dependent proteins required for sperm cell maturation and normal sperm production [2, 3, 4].

FSH production is regulated by the blood levels of testosterone and inhibin, both of which are produced in the testicles. FSH production increases when the levels of these hormones are low [2, 3, 4].

Function In Women

In women, FSH is essential to pubertal development and the proper function of the ovaries. FSH also regulates estrogen secretion [5, 6].

When hormone levels fall towards the end of the menstrual cycle, the pituitary gland is stimulated to produce more FSH. This increase in FSH, in turn, makes the ovary produce more estradiol and inhibin [5, 6].

The increase in these two hormones is sensed by the pituitary gland, thus reducing the release of FSH. FSH secretion rises in the first half of menstruation and decreases after ovulation. At the very end of the menstrual cycle, FSH starts to rise and the cycle begins again [5].

High FSH

The conditions we discuss here are commonly associated with high FSH levels, but this single symptom is not enough for a diagnosis. Work with your doctor to discover what underlying condition might be causing your high levels of this hormone and to develop an appropriate plan to improve your health.

Causes

In men, high FSH levels may indicate problems with the testes: when the testes don’t produce enough testosterone, FSH production rises [7].

In women, high FSH levels may indicate ovarian dysfunction or failure. If the ovaries do not produce enough estrogen, FSH production rises [8].

Menopausal women have naturally higher FSH levels [8].

The most common causes of high FSH levels include:

  • Menopause [8]
  • Gonadal dysgenesis (non-functional ovaries) [9]
  • Autoimmune diseases, including thyroid disorders [10]
  • Genetic syndromes such as Klinefelter`s and Turner’s [11, 12]

Other causes of high FSH levels include:

  • Smoking [13]
  • Drugs, such as cimetidine (Tagamet) and spironolactone (Aldactone, Spiractin, Verospiron) [14, 15]
  • Viral infections, such as mumps [16]
  • Germ cell tumors [17]

Symptoms

Risks

In postmenopausal women, chronically high FSH levels are associated with an increased risk of osteoporosis. However, they are also linked to reduced incidence of type 2 diabetes [23, 24].

How to Lower FSH Levels

If your FSH levels are too high, talk to your doctor to determine which underlying condition may be causing this imbalance and what strategies may help you correct it.

Although low FSH levels can be easily corrected with medication such as birth control pills, the poor ovarian function or diminished egg pool reserve may not be fixed.

The following lifestyle changes may help lower FSH levels. However, consult your doctor before implementing them and never use them in place of what your doctor recommends or prescribes.

Diet

Eating a diet high in soy can help lower FSH levels. Taking large amounts of its proteins and isoflavones with the diet were found to lower FSH and increase estrogen levels in a meta-analysis of 47 studies [25].

Supplements

The following supplements lowered FSH levels in clinical trials

  • DHEA (two clinical trials on 174 women) [26, 27]
  • Omega 3 fatty acids (trial on 27 women) [28]
  • Traditional Chinese medicine, such as the Zishen Yutai pill [29]

Low FSH

The conditions we discuss here are commonly associated with low FSH levels, but this single symptom is not enough for a diagnosis. Work with your doctor to discover what underlying condition might be causing your low levels of this hormone and to develop an appropriate plan to improve your health.

Causes

The most common cause of low FSH levels is improper pituitary gland function, which can be caused by:

  • Kallmann syndrome (an inherited disorder) [30]
  • Polycystic ovary syndrome (PCOS) [31]

Other causes of low FSH levels include:

  • Stress [32]
  • Hormonal drugs, such as estrogen, testosterone, steroids, and oral contraceptives [33, 34, 35, 36]
  • Anorexia [37]
  • An under-active thyroid gland (hypothyroidism) [38]
  • Hyperprolactinemia (a condition with high prolactin levels in the blood) [39]
  • Eating a diet with large amounts of soy protein and isoflavones [40]
  • Alcohol abuse [41]
  • Meningitis [42]

Symptoms

  • Delayed puberty [7, 43]
  • Total or partial infertility [44]
  • Erectile dysfunction [39]
  • Irregular menstrual cycles [45]

Risks

In postmenopausal women, low FSH levels are associated with a higher risk of diabetes and prediabetes [46].

A lower FSH level is also associated with an increased incidence of ovarian cancer in women [47].

How to Increase FSH Levels

If your FSH levels are too low, talk to your doctor to determine which underlying condition may be causing this imbalance and what strategies may help you correct it.

Your doctor may prescribe hormone replacement therapy with follitropin alfa. This hormone has a similar structure to FSH but is obtained through genetical engineering. It is used as a fertility treatment for both men with a low sperm count and women with underdeveloped follicles [48].

Although it is generally safe, follitropin alfa has been reported to cause headaches, nausea, and skin irritation [48].

The following lifestyle changes may help raise FSH levels. However, consult your doctor before implementing them and never use them in place of what your doctor recommends or prescribes.

Lifestyle

You should refrain from eating a diet with too much soy. Large amounts of soy protein and isoflavones can suppress FSH levels [40].

Reducing your alcohol intake may also prevent low FSH levels [41].

Supplements

The following supplements increased FSH levels in clinical trials.

FSH Testing

Lab results are commonly shown as a set of values known as a “reference range”, which is sometimes referred to as a “normal range”. A reference range includes the upper and lower limits of a lab test based on a group of otherwise healthy people.

Your healthcare provider will compare your lab test results with reference values to see if your FSH results fall outside the range of expected values. By doing so, you and your healthcare provider can gain clues to help identify possible conditions or diseases.

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don’t panic if your result is slightly out of range – as long as it’s in the normal range based on the laboratory that did the testing, your value is normal.

However, it’s important to remember that a normal test doesn’t mean a particular medical condition is absent. Your doctor will interpret your results in conjunction with your medical history and other test results.

And remember that a single test isn’t enough to make a diagnosis. Your doctor will interpret this test, taking into account your medical history and other tests. A result that is slightly low/high may not be of medical significance, as this test often varies from day to day and from person to person.

People normally measure their FSH levels when they are [8]:

  • Going through menopause
  • Having difficulty getting pregnant
  • Having irregular menstrual periods
  • Having symptoms of pituitary or hypothalamic disorders
  • Having symptoms of testicular or ovarian disease

An FSH test measures the amount of FSH in a blood sample and is routinely used to determine why a couple cannot conceive a child [52].

Measuring FSH levels can reveal whether the ovaries or testes are functioning properly by evaluating sperm count and egg supply [52].

This test can also be used to determine why a child is going through puberty early or late (or not at all), as well as to evaluate menstrual disorders [52].

Normal Adult Reference Range:

Male:

  • Before puberty: 0-5.0 mIU/mL
  • During puberty: 0.3-10.0 mIU/mL
  • Adulthood: 1.5-12.4 mIU/mL

Female:

  • Before puberty: 0-4.0 mIU/mL
  • During puberty: 0.3-10.0 mIU/mL
  • Adult, premenopausal women: 4.7-21.5 mIU/mL
  • Adult, postmenopausal women: 25.8-134.8 mIU/mL

About the Author

Carlos Tello

Carlos Tello

PhD (Molecular Biology)
Carlos received his PhD and MS from the Universidad de Sevilla.
Carlos spent 9 years in the laboratory investigating mineral transport in plants. He then started working as a freelancer, mainly in science writing, editing, and consulting. Carlos is passionate about learning the mechanisms behind biological processes and communicating science to both academic and non-academic audiences. He strongly believes that scientific literacy is crucial to maintain a healthy lifestyle and avoid falling for scams.

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