male fertility and hormones

Hormones….. they’re just a female thing right?

Not at all!!! Hormones are an essential part of our health and when it comes to male fertility they are absolutely crucial in sexual development, sex drive and sperm production.

There are several hormones that play a key role in male fertility and interestingly many of them are the same hormones that are present in women.

They are:

  • Testosterone (T)
  • Dehydrotestosterone (DHT)
  • Follicle Stimulating hormone (FSH)
  • Luteinising hormone (LH)
  • Oestrogen
  • Prolactin
  • Thyroid Stimulating hormone (TSH)
  • Gonadotropin Releasing Hormone (GnRH)

Everyone is well aware that a hormone imbalance within a woman will affect her menstrual cycle, fertility, mood and emotions. Yet, there is little awareness given to how hormones can affect a man’s fertility.

A man’s testicles are the equivalent of a woman’s ovaries. Testes and Ovaries are reproductive glands which produce gametes (sperm or eggs) as well as sex hormones. As glands within the body, the testicles are stimulated by hormones (FSH and LH) within the blood which are controlled by the brain via the pituitary gland.

These hormonal messages stimulate the testes to produce sperm (spermatogenesis) and the release of sex hormones (testosterone, DHT and inhibin B) into the blood. In the case of the testicles, the main hormone that is released is testosterone. Testosterone then acts, amongst other things, as part of a feedback loop to the pituitary gland controlling the rate of FSH and LH release, thus controlling testicular function and sperm production.

Follicle stimulating hormone (FSH) and Luteinising hormone (LH)

In a woman, FSH and LH are responsible for the growth of the follicle and the release of the egg. In the man, however, FSH and LH are the hormones that stimulate the process of spermatogenesis (sperm production) and testosterone production. FSH and LH work as a pair and act on 2 sets of cells within the testes which are crucial for sperm production, the Sertoli cells and Leydig cells.

Sertoli cells (stimulated by FSH) are like a facilitator and are there to support the production of sperm, whilst Leydig cells (stimulated by LH) are responsible for synthesising testosterone and releasing it into the blood. In addition, Sertoli cells release the hormone inhibin B which has regulatory effects on the pituitary gland and the brain to keep the hormonal system in balance.

FSH and LH are in effect the messengers sent to the factory telling it to get to work whilst the Sertoli cells and Leydig cells are the workers activated by these messages.

Testosterone (T) and Dehydrotestosterone (DHT)

Stereotypically known as the male hormone, testosterone is another key player in sperm production but isn’t quite as crucial as some men might think. DHT and even oestrogen are essential in sexual development. Again, they are hormones that are present in both sexes.

In men, testosterone together with DHT promotes the development of male characteristics such as hair growth, muscle development and the development of the penis and testicles at puberty. In women, testosterone also promotes hair and muscle growth, but to a lesser degree, whilst also helping with sex drive and cognitive function.

As mentioned above, testosterone is produced by the Leydig cells meaning as sperm are produced, testosterone levels increase. Increased testosterone levels within the blood are picked up by the pituitary gland which then adjusts the level of FSH and LH being released in order to control the level of sperm production.

This is really important to note for any man who considers taking testosterone to improve his sperm quality or has been taking anabolic steroids (a synthetic hormone that mimics testosterone) for muscle development. Artificially supplementing testosterone may reduce spermatogenesis; if the brain senses higher levels of testosterone, it’s going to assume that the testicles are doing their job and decrease the amount of FSH and LH being released decreasing sperm production.

In fact, raised levels of testosterone can work as a contraceptive. If a man needs to take testosterone for medical reasons, this has to be closely monitored by a medical professional.

Interestingly, testosterone’s role in sperm production isn’t actually as significant as some may think. It definitely plays an important role as it’s responsible for “manliness” whilst also supporting sperm production and differentiation.

Low testosterone levels aren’t always a terrible sign; many men have lower testosterone levels yet still have healthy sperm.


Oestrogen is often referred to as a female hormone but just as testosterone is present in women, oestrogen is also present in men. In fact, there is no normal man who has doesn’t have a certain amount of oestrogen.

In women, oestrogen plays a dominant role in sexual development and is responsible for the proliferation of the endometrial lining, regulation of the menstrual cycle and egg development among many other things.

In a man, oestrogen plays an important role in balancing testosterone whilst also contributing to sex drive, maintaining erections, bone strength and the closure of the epiphyses (round ends) in bones.

Generally, however, oestrogen levels aren’t of too much concern in men unless they are unusually high. High levels of oestrogen need to be investigated to discount any serious underlying issues.


Prolactin (think pro lactation) is the hormone involved in breast milk production. Not one that comes to mind as being relevant to sperm production, yet strangely it is.

Within the testicles and vas deferens (the pipe carrying the sperm from the testicles to the penis) there are prolactin receptors. These receptors respond to the presence of prolactin in the blood and have a direct influence on sperm production through the Leydig cells which as we know contribute to testosterone production.

As with oestrogen, prolactin isn’t often of concern for a man. However, if levels are out of normal range and certainly if they’re raised, then further investigations need to be done.

Raised prolactin levels in men have been linked to breast growth (gynecomastia), lower sex drive and infertility.

Thyroid stimulating hormone (TSH)

This one is pretty self-explanatory from its name. Thyroid Stimulating Hormone does exactly what it says it does, stimulates the thyroid.

The thyroid is an important part of the endocrine system (hormones and glands) and plays a key role in regulating our metabolism and our hormones.

Thyroid issues in men are rare, but when they do occur they will affect erectile function and sperm quality across all parameters due to the thyroid’s role in regulating hormone production.


To summarise…. It’s complicated but hopefully we’ve given you a sense of what’s going on and how important hormones are when it comes to sperm production.

The regulation and role of hormones in fertility is a very complicated affair but an integral part of the whole picture.

Male hormone testing really should be part of routine fertility testing for men. Unfortunately, however, this isn’t something that happens as standard within the NHS and is often overlooked until much further down the line in a man’s fertility assessment.

Getting a hormone assessment will give a good picture of how well the testicles are functioning and any imbalance in hormones will highlight the need for further investigations.

It’s important that if you’re taking a male fertility hormone test, you’ve got the right support and direction following your results.

Hormone tests will often be run by an Andrologist / Urologist where appropriate treatment options can be discussed with you.