Ovarian stimulating hormone (FSH)


Follicle-stimulating hormone (FSH) is a hormone secreted by the pituitary gland that regulates the production and growth of follicles in the ovaries for women and sperm maturation for men. Its secretion becomes active during the sexual maturation period.

In women, FSH controls the initial stage of the menstrual cycle, causing active follicle growth in the ovary and significant estrogen release into the bloodstream. FSH and LH concentrations peak in the middle of the cycle, stimulating the ovulation process. In the second stage of the cycle, FSH ensures progesterone production. If pregnancy doesn’t occur, FSH levels decrease, leading to reduced progesterone and estrogen concentrations, and the shedding of the uterine lining – menstruation begins.

FSH secretion is regulated based on the principle of negative feedback, where high concentrations of estrogen and progesterone suppress hormone production, while low concentrations enhance it.

In men, FSH contributes to spermatogenesis during adolescence and stimulates testosterone production. After sexual maturation, hormone levels remain somewhat stable and contribute to sperm production.

Changes in FSH concentration, especially disruptions in its production cycle in women, can lead to reproductive function disorders.

Synonyms for FSH testing include follicle-stimulating hormone, FSH assay, blood test for FSH, puberty-stimulating hormone, and gonadotropin.

Blood tests for FSH are conducted to assess reproductive function in both men and women. Reasons for this test include infertility, recurrent miscarriages, poor sperm analysis results, delayed or accelerated sexual maturation, menstrual irregularities, chromosomal abnormalities, and signs of pituitary or ovarian dysfunction.

  • Regular FSH testing is recommended during hormone therapy to evaluate treatment effectiveness.
  • To conduct the FSH test, blood is drawn from a vein and FSH concentration in the serum is analyzed.
  • Preparation for the analysis includes fasting for 8-12 hours, avoiding food but allowing water intake. For women, the test is typically performed on days 2-4 of the menstrual cycle, unless instructed otherwise by a doctor. Strenuous exercise, mental stress, and tension should be avoided 3-4 days prior to the test as they can affect the results.

Infections in the body are contraindications for testing, and ensuring good health before sampling is essential. Discontinuing hormonal medications and oral contraceptives several weeks before the test is preferred, but it should be done under medical consultation.

Smoking should be avoided an hour before the test, and resting before entering the room is advised.

Results of follicle-stimulating hormone (FSH) analysis are measured in international units per milliliter (mIU/mL). Below are the reference values according to age and gender:

FSH levels for males:

  • 0 – 1 year: Less than 3.5 mIU/mL
  • 1 – 5 years: Less than 1.45 mIU/mL
  • 6 – 10 years: Less than 3.04 mIU/mL
  • 11 – 14 years: 0.36 – 6.29 mIU/mL
  • 15 – 20 years: 0.49 – 9.98 mIU/mL
  • Above 21 years: 0.95 – 11.95 mIU/mL

FSH levels for girls and women:

  • 0 – 1 year: 0.10—11.30 mIU/mL
  • 1 – 5 years: 0.68-6.70 mIU/mL
  • 6 – 10 years: 1.00-7.40 mIU/mL
  • 11 – 14 years: 1.00-9.28 mIU/mL
  • 15 years and older:
  • Follicular phase: 3.03-8.08 mIU/mL
  • Ovulation phase: 2.55-16.69 mIU/mL
  • Luteal phase: 1.38-5.47 mIU/mL
  • Pre-menopausal: 1.7 – 21.5 mIU/mL
  • Post-menopausal: 26.72-133.41 mIU/mL

For pregnant women, hormone levels are expected to be below 0.2 mIU/mL, irrespective of the gestational age.

Analytical results:

Elevated FSH levels may indicate:

  1. Sexual development disorders, due to congenital conditions such as Turner syndrome, Klinefelter syndrome, Swyer syndrome, etc.
  2. Menopause.
  3. Surgical removal or dysfunction of ovaries or testes due to inflammation, radiation effects, acute or chronic poisoning, injuries, infections, etc.
  4. Pituitary gland tumor and other tumors secreting FSH.
  5. Endometritis (inflammation of the uterine lining).
  6. Early sexual maturation.

Decreased hormone levels may indicate:

  1. Pregnancy.
  2. Hypothalamic-pituitary insufficiency (growth retardation, dwarfism).
  3. Sheehan syndrome (necrosis of the pituitary gland).
  4. Increased prolactin hormone levels in the blood (hyperprolactinemia).
  5. Loss of appetite and malnutrition.
  6. Hemochromatosis (iron accumulation in the body).
  7. Renal failure affecting the pituitary gland (hypothalamic-pituitary insufficiency).
  8. Polycystic ovary syndrome.
  9. Kallmann syndrome (congenital secondary growth deficiency).
  10. Isolated congenital deficiency of FSH secretion.
  11. Tumors in the ovaries, testes, or adrenal glands secreting estrogen or androgens.

Hormone levels can be elevated due to certain medications (such as hydrocortisone, gonadotropin-releasing hormone, etc.) and anti-tumor drugs, among others. Recent examinations such as MRI, radiation therapy, and monoclonal antibody injections may also affect the results.

In case of deviation from the normal range of FSH concentration, consultation with gynecologists, andrologists, pediatricians, and endocrinologists is necessary. A series of additional tests should be conducted, such as ultrasound imaging of the reproductive organs, radiography of the pelvic area, ultrasound of the adrenal glands, etc. Additionally, comprehensive hormone profiling through blood analysis is recommended, including:

  • Luteinizing hormone (LH)
  • Total and free testosterone
  • Prolactin, estrogen, and progesterone hormones
  • Mullerian hormone
  • Pituitary hormones: ACTH, TSH, growth hormone

Further tests may be added if necessary. It’s preferable for men to undergo a sperm analysis if not done previously.

  • N.V. Sklyar, L.V. Suturina, L.F. Sholokhov, M.A. Sharifullin, E.V. Ermolova. Features of hormonal status in women with infertility associated with uterine fibroids. Acta Biomedica Scientifica. 2005. No. 5.
  • Ekaterina Viktorovna Ponomareva, Svetlana Nikolaevna Didenko, Maria Leonidovna Zolotavina. Changes in hormonal activity indicators in women with disrupted reproductive systems and secondary amenorrhea. APRIORI. Series: Natural and Technical Sciences. 2014. No. 5.