Male hormones and fertility issues
The functions of the testes are controlled by the Gonadotrophins which travel via the bloodstream to the testes.
LH acts on specialised cells within the testes and stimulates release of the male sex hormone, testosterone. FSH acts on a separate population of cells within the testes to stimulate the production of sperm.
During puberty testosterone is essential for growth, increasing muscle bulk, development of the penis and for male pattern hair growth. In adult life it is important in maintaining the strength of your muscles and bones, improves general well-being and energy levels and is intricately involved in both your normal sex drive (libido) and erections. Lack of the male sex hormone, testosterone, is termed Hypogonadism.
What are the effects of a lack of male hormones?
Anything that affects the normal functioning of the testes can cause hypogonadism and sub-fertility. In this section we are concerned with problems caused by the lack of stimulation of the testes by the pituitary hormones LH and FSH. If the pituitary gland does not produce enough or any gonadotrophin hormones, this can affect fertility in men because:
- Reduced production of FSH will affect the numbers of sperm produced
- Reduced production of LH will affect the production of testosterone.
The normal function of the pituitary gland is most commonly disrupted by the presence of a pituitary tumour. Please be assured that these are benign tumours and not cancerous.
Pituitary tumours are actually swellings in the pituitary - as they grow they may destroy the cells in the pituitary that produce hormones including the gonadotrophins. Treatment to reduce or remove a pituitary tumour, using surgery or radiotherapy, may also affect the pituitary gland’s ability to produce these hormones.
Release of gonadotrophins from the pituitary is also absent in Kallmann’s Syndrome, a rare genetic syndrome frequently associated with absence of the sense of smell (anosmia). In Kallmann’s Syndrome the hypothalamus fails to release GnRH. The lack of stimulation of the pituitary by GnRH means that the pituitary in turn does not release LH and FSH.
What does this mean?
- Sub-fertility: In order for fertilisation to occur, a man’s semen must contain sufficient sperm which must be active and healthy. A normal sperm concentration is considered to be more than 20 million per ml. Fertilisation becomes less likely as the sperm concentration falls progressively below this level.
- Sexual function: Testosterone is an essential male hormone and is needed for the normal interest in sexual activity (libido) and helps erections to happen.
- Other effects: Hypogonadism affects more than sexual function and reproduction, important as these are. Other effects can include lack of energy, depression, loss of body and facial hair, muscular weakness and, in the long-term, Osteoporosis (the thinning of the bones). In some men a lack of testosterone can also cause Gynaecomastia (increased breast tissue).
When hypogonadism occurs during childhood or adolescence, puberty will not progress. As Kallmann’s Syndrome is present before birth it may also be associated with micropenis and undescended testes.
On a day-to-day basis, many men will find these effects of hypogonadism at least as important as the effects on fertility and sexual function.
As one Pituitary Foundation member explained: “…testosterone is much more to do with one’s emotional response to life’s setbacks than with one’s libido.”
Another member commented: “Gynaecomastia is acutely embarrassing for a man and does affect his self-esteem”.