FSH - follicle stimulating hormone: normal, high and low values in men and women

What is FSH? What does FSH stand for?

FSH, which acronym means follicle stimulating hormone, is a gonadotropin, a hormone involved in the regulation of both female gonads (ovaries) and male (testicles) and, more generally, of the reproductive system.

FSH is not the only gonadotropin, in fact, it acts together with LH (luteinizing hormone). These represent the two most expressed gonadotropins, but they are not the only ones. In fact, during pregnancy, the production of hCG (chorionic gonadotropin) is observed; a gonadotropin produced by the placenta, an endocrine-acting organ, temporarily present in pregnant women.

FSH and LH are glycoprotein hormones present in both men and women. Since the female and male reproductive systems are different, the function of the gonadotropins in the two sexes will manifest itself differently.
In woman: LH and FSH are involved in the menstrual cycle, ovulation (folliculogenesis and oogenesis) and in the production of estrogens (eg estradiol and 17 beta estradiol).
In theman: LH and FSH are involved in spermatogenesis (i.e. the process that leads to the production and maturation of spermatozoa) and in the production of testosterone at the level of Leydig cells, or the interstitial cells of the testis.

Gonadotropins have a trend pulsatile (i.e. intermittently), therefore, their release is not continuous, but has peaks (eg. monthly peaks, typically found in women of childbearing age).

Gonadotropin secretion takes place in gonadotropic cells located in the adenohypophysis, the anterior portion of the pituitary (gland located in the base of the skull), under the control of the hypothalamus.
The production and action of gonadotropins, therefore, is part of the hypothalamus-pituitary-gonadal axis.
They are released following the stimulation of the adenohypophysis by the GnRH (gonadotropin releasing hormone).
Once they are released, the woman's FSH (follicle-stimulating hormone) will induce the maturation of the ovarian follicles.

The ovarian cycle occurs simultaneously with the period (which culminates with menstruation).

The period corresponds to the variations of the uterus (organ of the female reproductive system, which monthly prepares to receive the product of conception; if this does not occur, the innermost layer of the uterus, the endometrium, undergoes flaking). The cells of the most superficial layer, which will thus be exfoliated, will be subsequently "replaced" by new cells, produced by the basal layer - which has a regenerative function.
The phases of the menstrual cycle are:

  • Menstrual phase (1st - 5th day)
  • Proliferative or follicular phase (6th - 14th day)
  • Secretory (secretory) or luteal phase (15th - 28th day)

Around the 14th - 15th day the ovulatory phase takes place.

The ovarian cycle corresponds to the stages of maturation of the follicles and oocytes, contained within the follicles (ovarian reserve).

Their maturation predisposes to ovulation, that is the outflow of the oocyte, which, if fertilized, will lead to the formation of the zygote - that is, conception.

The phases correspond to:

  • Follicular phase (1st - 14th day)
  • Ovulatory phase (14th - 15th day)
  • Luteal phase (15th - 28th day)

Shortly before the start of the follicular phase we observe menstruation which, by convention, corresponds to both the beginning of the menstrual cycle and the beginning of the ovulatory cycle.

Since the menstrual cycle and the ovulatory cycle are two different events, although they are closely connected, the presence of menstruation does not necessarily imply that ovulation has occurred correctly. Therefore, anovulatory menstrual cycles may exist, both as a result of physiological and pathological conditions (eg polycystic ovary syndrome or PCOS).

Shortly before ovulation there is an ovulatory peak in the production of gonadotropins andFSH, but especially the LH hormone. This is one of the times when we most typically find high FSH and LH values.

Follicle Stimulating Hormone or FSH

Trend of follicle-stimulating hormone during the menstrual cycle.

Normal values of FSH in humans

 FSH values vary according to gender and age.

In man i normal values of FSH I'm:

  • Child: 0-5.0 mIU / mL
  • Adolescent (pubertal age): 0.3-10.0 mIU / mL
  • Adult: 1.5-12.5 0 mIU / mL

Normal values of FSH in women 

 FSH values vary according to gender and age. Furthermore, in women of childbearing age we observe variations linked to the phase of the ovarian cycle (follicular, ovulatory, luteal).

In the woman i normal values of FSH I'm:

  • Child: 0-4.0 mIU / mL
  • Adolescent (pubertal age): 0.3-10.0 mIU / mL
  • Fertile age
    • Follicular phase: 1.0-8.8 mIU / mL
    • Ovulatory phase: 4.0-25.0 mIU / mL
    • Luteal phase: 1.0-5.1 mIU / mL
  • Menopause: 16.7-134.8 mIU / mL

The hormonal values in menopause, therefore, are different from the typical values of the fertile age.

High FSH

What are the high FSH values in men and women? As already mentioned, an increase in FSH values can occur in both men and women.

High FSH in humans

  • Child: greater than 5.0 mIU / mL
  • Adolescent (pubertal age): greater than 10.0 mIU / mL
  • Adult: greater than 12.5 0 mIU / mL

Causes of high FSH in humans

  • Developmental alterations
  • Genetic abnormalities (eg Klinefelter syndrome, a clinical condition also known as hypergonadotropic hypogonadism; Turner syndrome)
  • Hypothalamic tumors (also associated with increased GnRH production)
  • Pituitary adenoma
  • Trauma
  • Radiation
  • Chemotherapy
  • Infections (e.g. mumps)
  • Germinal tumors
  • Autoimmune Diseases
  • Acromegaly
  • Orchiectomy

The most frequent cause of high FSH in humans is hypogonadism (testicular failure), which is the inability of the male gonad to carry out spermatogenesis and / or to produce male sex hormones.
Since the testicle is "non-compliant", through a feedback mechanism, given the lack of production of sex hormones, the pituitary is stimulated in the production of a greater quantity of FSH, in order to stimulate and urge the testicle.

Symptoms of high FSH in humans

The symptoms associated with elevated FSH levels vary according to the triggering cause. In presence of primitive hypogonadism the symptoms I'm:

  • Testicular atrophy
  • Reduced size of the scrotum
  • Erectile dysfunction
  • Infertility
  • Asthenia
  • Reduced or absent libido

In the presence of a pituitary adenoma the symptoms more frequent are:

  • Headache
  • Visual disturbances
  • Hormonal alterations affecting other axes (e.g. PRL or prolactin alterations, GH etc)

In the presence of trauma, radiation, chemotherapy, infections we can note:

  • Ache
  • history of exposure to one of the following causes (e.g. chemotherapy treatment, exposure to radioactive sources or radiotherapy, etc.)

High FSH in women

What are the elevated FSH values in women?

  • Child: greater than 4.0 mIU / mL
  • Adolescent (pubertal age): greater than 10.0 mIU / mL
  • Fertile age
    • Follicular phase: greater than 8.8 mIU / mL
    • Ovulatory phase: greater than 25.0 mIU / mL
    • Luteal phase: greater than 5.1 mIU / mL
  • Menopause: over 134.8 mIU / mL

 Causes of high FSH in women

  • Amenorrhea
  • Menopause
  • Acromegaly
  • Ovarian failure
  • Hyperpituitarism
  • Pituitary adenoma
  • Hysterectomy
  • Menstruation
  • Hypothalamic tumor

The most frequent cause of high FSH in women is menopause. The ovary stops working and, to remedy this change, the pituitary intervenes by physiologically releasing a quantity of gonadotropins higher than normal, in order to stimulate and urge the ovary to restore its function. This response, however, will not occur as the ovary has physiologically lost its responsiveness to gonadotropins.

Since menopause is a physiological event, unless it is a premature menopause, this increase in FSH should not cause concern and, after this initial peak, the values will decrease until they reach the normal levels typical of menopause (values of fsh in menopause indicated above).
Therefore, in this case it is not necessary to lower the FSH.

Signs and symptoms of high FSH in women

Depending on the cause that led to the increase in the FSH hormone values, the symptoms vary.

During menopause or climacteric (i.e. the period that precedes, affects and follows menopause) - FSH symptoms in menopause

  • Irritability
  • Insomnia
  • Vaginal dryness
  • Hot or hot flashes

Suspected pituitary adenoma - FSH symptoms in case of pituitary adenoma

  • Headache
  • Visual disturbances
  • Hormonal dysfunctions affecting other hormones (eg prolactin, GH etc)

What to do in case of high FSH?
In case of high FSH it is advisable to contact the doctor and see which diagnostic and / or therapeutic procedure he recommends.

Low FSH

Low FSH in humans

Causes of low FSH in humans

  • Late puberty
  • Hypogonadotropic hypogonadism (Hypogonadism with low FSH and LH)
  • Anorexia
  • Hypothalamic changes
  • Hypophysectomy

Symptoms of low FSH in humans

  • Testicular failure
  • Drop in libido
  • Erectile dysfunction
  • Infertility

Low FSH in women

Causes of low FSH in women

  • Late puberty
  • Anorexia
  • Amenorrhea
  • Hypophysectomy
  • Hypothalamic changes
  • Ovarian cancer (also associated with high progesterone)

Symptoms of low FSH in women

  • Asthenia
  • Abulia
  • Reduced development of secondary sexual characteristics
  • Infertility

Factors that can alter the examination

Among the factors that can most frequently alter the examination we include i drugs, the habit of smoking and having done the test in a unsuitable day.
Since FSH values vary greatly depending on the menstrual phase a woman is in, the doctor's date for FSH analysis should be meticulously respected.
We can observe altered FSH values in pregnancy and also in particular conditions stress.

Exam preparation

The gonadotropins are measured on a blood sample, using a blood sample (blood tests). It is not necessary to be fasting, however, especially in women, it is advisable that the test be carried out on the right day, since the gonadotropin values undergo considerable monthly fluctuations.

When is the exam required?

FSH assay may be required following problems with infertility, in presence of cycle menstrual irregular or absent, in case of suspected pituitary adenoma or hypothalamic tumor.

It may be useful to perform a thorough hormone analysis, evaluating in addition to FSH, also LH, male sex hormones (testosterone, dhea) and / or female hormones (estrogen and progesterone).
Hormonal analyzes are helpful for the classification of the existing clinical condition:

  • High estradiol: it is associated with normal ovarian functioning, therefore the FSH values can be elevated following an increase not from ovarian insufficiency, but from a central cause (e.g. higher production of GnRH secondary to hypothalamic alterations or higher production of FSH and secondary LH pituitary adenoma, resulting in an increase in female hormone)
  • Low estradiol: it is associated with reduced ovarian function (eg menopause)
  • Increased pituitary hormones (eg. Prolactin) à can suggest the presence of a pituitary adenoma.

In case of infertility, a follitropin-based treatment can be used, in order to promote and favor the development of the oocyte, allow ovulation and therefore make the woman fecundable (increasing her fertility).

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