How does low testosterone affect male fertility?

Testosterone is the best-known of the male sex hormones. It is widely recognized for being associated with the production of sperm, as well as muscle mass, bone development and sex drive. Low testosterone can therefore have a negative effect on all these characteristics. However, although the role of testosterone in sperm production is important, low levels do not necessarily equate to infertility in men.

In this IVI article, we look at what causes low testosterone, the relationship between low testosterone and fertility, and what men can do to improve testosterone levels, including some lifestyle factors such as weight management. Medical intervention through testosterone supplements is also an option, but with the important caveat that such supplements will almost certainly cause infertility. We’ll explain the reasons for this apparent contradiction, and take a look at some other ways that we can help men with low testosterone who want to become parents.

What is the role of testosterone in sperm production?

Testosterone is produced in the testes because of the presence of follicle stimulating hormone (FSH) and luteinizing hormone (LH). These hormones are released by the pituitary gland situated at the base of the brain. Working in balance with these and other hormones in the endocrine system, testosterone helps to generate sperm in the testes. Thus, although testosterone is a necessary component for sperm production, it is not the direct stimulant. Even when a man has low testosterone and may notice other effects on his health and wellbeing, there may still be sufficient levels for the production of sperm.

Low testosterone level: what causes it?

Testosterone levels naturally decline with age, leading to symptoms such as reduced libido, erectile dysfunction, and a low sperm count. However, this age-related decline is normal and would not lead to a diagnosis of hypogonadism, the medical term for the condition. Low levels associated with a natural decline could be caused by:

• Injury to the testicles
• A testicular infection such as orchitis
• Medications such as opiate-based analgesics
• Disorders that affect hormonal levels such as high prolactin levels or tumors of the pituitary gland
• Chronic diseases including liver or kidney disease, HIV/AIDS, or obesity.

The impact of low testosterone levels can lead to dysfunction of processes which are normally regulated by the hormone. This could lead to loss of body hair, muscle bulk and bone density as well as increased body fat. Untreated hypogonadism can eventually lead to an overall energy reduction, testicular shrinkage, and osteoporosis.

How does a low testosterone level impact fertility for men?

Although a low level of this essential hormone does not automatically make a man infertile, there comes a point where fertility is inhibited because testosterone is one of the necessary elements for sperm production.

Ironically, the greater risk of infertility comes with the ‘cure’ for low testosterone levels, which is supplements in the form of patches, gels, injections, or oral medications. Testosterone replacement can restore a man’s libido and have an impact on other symptoms by improving muscle and bone mass, but in fact supplements increase, rather than alleviate, the risk of complete infertility. This is because the supplements go straight into the bloodstream. The production of testosterone is controlled by the brain in a complex ‘negative feedback’ loop. This detects when there is not enough of the hormone in the bloodstream and stimulates the brain to produce GnRH (Gonadotropin-Releasing Hormone) which in turn stimulates the testes to produce testosterone.

The same feedback loop operates when testosterone from a supplement is introduced directly into the bloodstream. The brain detects that there is enough of the hormone circulating in the blood and therefore switches off production in the testes, which is where it is needed to produce sperm. The result can quickly be a sperm count of zero. This effect is so pronounced that it has been considered as a means of contraception.

How to improve testosterone level

Since testosterone replacement therapy is effectively out of the question for men who want to become fathers, what other means are available to improve levels and protect their fertility?

• Weight management can have a major impact on testosterone levels. This is because excess fat, especially around the belly, converts testosterone into oestrogen. One study demonstrated that 70% of morbidly obese men have a testosterone deficiency, and that this can be reversed by losing weight.
• Stopping smoking can also have a positive impact on fertility, because smokers generally have lower levels of a whole range of hormones, including those that regulate fertility.
• Medical treatment that avoids the infertility effect of testosterone replacement is an option for some people. If the testosterone deficiency is due to a pituitary disorder, treatment with the hormone human chorionic gonadotropin (hCG) can increase testosterone levels without disrupting sperm production.

What fertility help is available?

For men with low testosterone who wish to retain their fertility, the fact that the apparently simple solution of testosterone replacement therapy is not an option can come as a big disappointment. But it’s not a reason to give up your hopes of a family of your own. Fertility treatments, such as Artificial Insemination (AI) and in vitro fertilisation (IVF) are available, either of which may be suitable, depending on your circumstances and the fertility status of your partner.

Both treatments have as part of their procedure a process known as sperm optimization, in which a semen sample is optimized in the laboratory by our andrologists. This means that even for men with a low or very low sperm count, healthy sperm can be selected and concentrated for use in the procedure to maximize the chances of conception. A technique known as Intracytoplasmic Sperm Injection (ICSI) which can be used as part of an IVF treatment, offers even more help through selecting a single healthy sperm and micro-injecting it directly into an egg.

Contact us at IVI

If you’d like to know more about these techniques or any other issue arising from low testosterone and its impact on your fertility, get in touch with us at IVI. As part of the world’s largest Assisted Reproduction group and with more than 75 clinics spread over nine countries, there’s a very good chance that we can help.