Follicle-stimulating hormone is one of the gonadotropins – hormones secreted by the anterior part of the pituitary gland, which are responsible for the regulation and control of growth, sexual development and reproduction.
Follicle-stimulating hormone is secreted from the beta-cells by the anterior portion of the pituitary gland (known as the adenohypophysis) in response to the gonadotropin-releasing hormone produced by the hypothalamus (so-called hypothalamic-pituitary-gonadal axis).
In case of infertility, delayed or precosious puberty the FSH levels in the blood should be evaluated.
Standard ELISA/CLIA/RIA assays are used to estimate FSH levels. Rapid tests may be used to check whether FSH level is normal or not.
Concentrations of the FSH depend on the age of a person and phase of the menstrual cycle.
The FSH levels start to rise soon after the beginning of the menstruation with its peak at the 12th day of the menstrual cycle (before the ovulation occurs), afterwards its levels decrease gradually until the day 18 to the base values.
Therefore, FSH levels vary greatly in women, according to the phase of the cycle and woman’s age.
- Age 0-7 years: <6.7 mIU/mL
- Age 8 years to adult:
- Follicular phase: 3.1-7.9 mIU/mL
- Ovulation peak: 2.3-18.5 mIU/mL
- Luteal phase: 1.4-5.5 mIU/mL
- Postmenopausal: 30.6-106.3 mIU/mL
- Age 0-7 years: <6.7 mIU/mL
- Age 8 years-adult: 1.3-19.3 mIU/mL
The pituitary gland increases when the values of sex hormones (estrogens, testosterone) are decreased due to various reasons.
- Premature ovarian failure (premature menopause) is a term used to define the loss of ovarian function before a woman reaches age of 40;
- Premature ovarian aging – a low ovarian reserve, meaning that the woman’s ovaries contain a low number of good quality eggs, which can eventually mature and be released during ovulation;
- Turner syndrome is a genetic disorder when one X chromosome in woman is missing (45, X0). Women who suffer from this syndrome have a short stature, webbed neck and primary amenorrhea. Other features of the syndrome include diabetes mellitus, hypothyroidism and heart defects;
- Congenital adrenal hyperplasia is a term used to describe several autosomal recessive disorders which affect the production of glucocorticosteroids, mineralocorticoids and steroid hormones;
- Swyer syndrome (XY gonadal dysgenesis) is a disorder when a person with a typical male karyotype has a female appearance;
- Testicular failure is a condition characterized by low testosterone levels due to decreased production;
- Complete testicular feminization syndrome is a condition in which the cells do not respond to androgens and, therefore, male genitalia and secondary sexual characteristics fail to develop;
- Klinefelter syndrome is a chromosomal abnormality in which a person with a male karyotype has an extra X chromosome;
- Systemic lupus erythematosus is a chronic autoimmune disorder which affects various organs;
- Ovarian tumors, neoplasms of the testes or adrenal glands, which produce estrogen or androgens and, in turn, inhibit the production of FSH;
- Polycystic ovarian syndrome is a disorder caused by the increased androgen levels. Signs of PCOS include irregular menstruations or absence of the periods, hirsutism (excessive hair growth), acne and infertility and is associated with an increased risk of obesity, diabetes and metabolic syndrome;
- Kallmann syndrome is a genetic disorder characterized by the delayed puberty and impaired olfaction caused by the gonadotropin-releasing hormone (GnRH) deficiency;
- Hypothalamic suppression (hypothalamic hypogonadism) is a disorder characterized by the decreased production of gonadotropin-releasing hormone and as the result decreased levels of FSH, LH and sex hormones;
- Gonadotropin deficiency is an insufficient secretion of FSH and LH, which leads to the development of the hypogonadotropic hypogonadism (secondary hypogonadism);
- Hypopituitarism (pituitary insufficiency) is a condition in which the production of hormones by the pituitary gland is decreased;
- Hyperprolactinemia is considered the most common disorder of the pituitary gland characterized by the increased levels of serum prolactin (PRL>20 ng/mL) in the absence of pregnancy or lactation;
- Anorexia nervosa is an eating disorder when a person is afraid of gaining weight and loses it due to significant food restrictions. When person’s weight is too low periods do not occur anymore and secondary amenorrhea develops;