Testosterone and Male Fertility: Does Low T Affect Sperm Count and Quality?

Written by Mannat Fertility Editorial Team | Medically reviewed by Dr. Archana Agarwal, MBBS, DipGO, RCOG (Associate), Medical Director, Mannat Fertility Clinic, Bangalore

Do you know that taking testosterone can actually reduce your sperm count rather than improve it? This is one of the most commonly misunderstood areas in the whole of reproductive medicine. A lot of men assume that testosterone is going to improve their sperm count and quality, and what is genuinely surprising is that some clinicians assume the very same thing. In practice it very often works the other way round. So it is important for you to understand how testosterone actually behaves in the context of sperm production, and this holds whether you are investigating your fertility or you are considering treatment for low T.

How Does Testosterone Actually Affect Sperm Production?

Testosterone does not stimulate sperm production directly, which is the way most people imagine that it works. Spermatogenesis depends instead on a hormonal chain. Your hypothalamus releases GnRH, and this is what triggers the pituitary into producing FSH and LH. The FSH then stimulates your Sertoli cells, which are the structural support cells inside the testes that nurture the developing sperm, while the LH drives your testes into producing testosterone locally, and this is known as intratesticular testosterone, or ITT. The thing to note here is that it is this intratesticular testosterone, produced inside the testes at concentrations which are far higher than anything in your bloodstream, which is essential if sperm are going to mature.

What Happens When You Add Testosterone From Outside?

When testosterone gets taken externally, whether that is as TRT patches or gels or injections or implants, it raises the testosterone levels in your blood. This then signals to your hypothalamus and your pituitary that the body already has enough of it, so they reduce or completely stop their own output of GnRH, FSH and LH. Your testes are now left without any FSH or LH stimulation, so they reduce their own testosterone production and the spermatogenesis slows down or halts altogether. The result of this can be severe oligospermia, meaning a very low sperm count, or it can be azoospermia, and sometimes that follows after only a few months of TRT use.

A comprehensive review published in PMC confirms that exogenous testosterone suppresses male fertility by augmenting the negative feedback on the HPG axis, and moreover it notes that this very mechanism has been investigated as a potential male contraceptive. So the suppression here is not theoretical at all. It is well documented and it is clinically significant.

Does Low Endogenous Testosterone Affect Sperm Production?

Yes it does, however this is a different situation from the suppression which TRT induces. Men who have secondary hypogonadism, which is where the hypothalamus or the pituitary is not producing adequate signalling hormones, have low testosterone precisely because their LH and FSH are low to begin with. Sperm production in these men is impaired as well, but the problem here originates in the signalling chain rather than in the testes themselves, and this is a treatable cause of male infertility.

Crucially, the treatment for secondary hypogonadism in men who want to conceive is not exogenous testosterone, because that would only worsen the situation for them. The goal instead is to stimulate the testes into their own production.

What Are the Treatment Options for Hypogonadal Men Who Want Children?

For men who have secondary hypogonadism and are seeking fertility, there are several approaches which get used:

• Clomiphene citrate (Clomid) which is a selective oestrogen receptor modulator, or SERM, that blocks the negative feedback at the hypothalamus and increases GnRH and subsequently FSH and LH. This stimulates your testes into producing more testosterone and more sperm, and it does this without shutting down the spermatogenesis.
• hCG (human chorionic gonadotropin) which acts like LH and directly stimulates testicular testosterone production. It is often used on its own or in combination with FSH for men who want to preserve or restore their fertility.
• Anastrozole which is an aromatase inhibitor, and it is sometimes used where testosterone is being converted into oestrogen at high rates and suppressing the feedback axis.

Moreover, all of these approaches preserve or improve your fertility instead of trading it away.

What About Anabolic Steroids?

The very same suppressive mechanism applies here, and often it applies far more severely. Anabolic-androgenic steroids, or AAS, which are used by bodybuilders, can cause spermatogenic suppression which is both rapid and profound. Recovery once the AAS have been stopped can take up to 20 months, and it is less predictable than recovery after TRT is. Part of the reason for this is that many AAS users are otherwise healthy young men whose baseline testicular function was completely normal, which means that the shutdown was entirely drug-induced rather than reflecting any pre-existing dysfunction.

It is recommended that any man who has used AAS and is now investigating infertility discloses this fully to his specialist. It is a common finding and it is one which changes the investigation and the management approach considerably.

If you have questions about testosterone, about your sperm count, or about male hormone-related infertility, our team at Mannat Fertility can review your hormone panel and your semen analysis together rather than interpreting either of them in isolation. Book a consultation with our male fertility specialists in Bangalore.

This article is for general educational purposes and is not a substitute for personalised medical advice from your fertility specialist.