How male hormone deficiency can impact both mood and libido

Testosterone levels drop by 1% a year after the age of 30, so should all middle-aged men be considering hormone replacement therapy to boost their mood and libido?
How male hormone deficiency can impact both mood and libido
A man sitting at the end of a bed, deep in solemn thought.
A man sitting at the end of a bed, deep in solemn thought.
A man sitting at the end of a bed, deep in solemn thought.

WITH the relentless rise of the wellness industry, it is hard to avoid the feeling that we could all be doing more to achieve optimum health. In recent years, testosterone replacement therapy (TRT) has been added to the list of treatments purported to boost health, amid concerns that levels of the male hormone are dropping.

In the US, a study published in 2017 in the Journal of Urology found that prescriptions for testosterone had risen 300% since 2001, while demand has also soared in Britain. Alongside prescription testosterone, there has also been a boom in unregulated online supplements, an industry which undoubtedly exploits men’s vulnerability when it comes to ‘masculine’ attributes such as strength and libido.

Testosterone is a hormone produced primarily in the testicles (it is also produced in a woman’s ovaries in small amounts) and is key to regulating sex drive, bone mass, fat distribution, muscle mass and strength, and in the production of red blood cells and sperm. Most men will experience a gradual fall as they age — typically by about 1% a year after age 30. However, while some US studies claim testosterone levels are decreasing across the board, even in younger men, other research is less than conclusive. So, when does a lack of testosterone become a problem and should more men be looking at TRT as an option?

Dr Emmett Byrne is a GP who runs a clinic which specialises in men’s health in Bray, Co Wicklow. He treats men from all over the country for testosterone deficiency, but emphasises that TRT is not a cure-all. He says testosterone deficiency often becomes an issue for men when it begins to interfere with their quality of life.

“When you have testosterone deficiency, you lose your energy to do the things that keep you healthy and the things you enjoy — your mood drops, and there are different knock-on effects that are seen over time,” he says.


While it is difficult to ascertain the number of men taking TRT in Ireland, Byrne says his patient base is growing.

“We have patients who would have always managed their health, but as they get older, they realise they are slowing down, no matter what they do. These are guys who are very attentive towards their health and they just want to maintain their quality of life. Then I would occasionally see someone who might have been a bodybuilder and taken an anabolic steroid which might have affected his libido. The people who are probably most vulnerable are people with cardiometabolic disorders such as diabetes and obesity.” 

While a reported dip in testosterone has been blamed on everything from pollution to availability of online pornography, Byrne says that outside of a particular medical condition, the main reasons he sees are age or lifestyle-related, from poor nutrition to stress.

Dr Emmet Byrne.
Dr Emmet Byrne.

“You have to distinguish between classical and non-classical [testosterone deficiency], classical occurs when you are born with a defect or there is a direct cause for your low testosterone, it could be a pituitary tumour or something like Kallmann syndrome. All of that can be managed medically, you see a specialist, and so on. The stuff where you are getting the deterioration with age, health neglect, or stress is more non-classical, those are the areas that are being missed in the general population. We must remember that testosterone deficiency is the second most common endocrine problem for men, after diabetes.” 

He says a lot of the symptoms of testosterone deficiency that he sees can be sexual and psychological.

“Sexually, classic symptoms would be low libido or erectile dysfunction, while psychological would be loss of confidence, anxiety, possibly depression. There can also be physical changes — guys get more belly fat, they lose a bit of muscle. If you go on a deeper dive, you can get things like hair loss, gynecomastia (fat in breast tissue), osteoporosis, constant fatigue, and low-trauma fractures.” Byrne says other interventions will be tried before he prescribes TRT.

We only treat men when they need it. We will try to address issues such as exercise, nutrition, sleep hygiene, and stress management first.

He is aware of anecdotal cases of men acquiring testosterone online and self-administering, and emphasises the importance of medical supervision while taking testosterone.

“We monitor our patients, and do regular blood tests. If guys are unwell, they will not get themselves healthy by just taking testosterone ... I don’t treat guys if they are reckless with their lives and are just taking testosterone.” 

There are also certain circumstances in which TRT will not be prescribed, says Byrne. “We do a prostate check, as I would not give it if I was worried about prostate cancer, or if someone had obstructive sleep apnoea, a family history of male breast cancer, or heart failure — testosterone helps with heart failure, but at that stage, we need to be careful. I also wouldn’t give it to somebody who wants to have a family. It is not a contraceptive, but it can reduce sperm count. If you already have a low sperm count, that needs to be discussed.” 


TRT is administered in two forms, gel or injection.

“The two main licensed products in Ireland are a gel-delivery product and a deep muscle injection, Nebido, which would last for anything between 10-12 weeks, and then we repeat the injection,” says Byrne. “We start with a gel, and see how guys do on that. We then offer the option of the Nebido or to stay on the gel. The gels are shorter-acting and are used on a daily basis. People tend to be happy with whatever suits them.”

While GPs are allowed to prescribe TRT, it is not widely utilised. Byrne says the reluctance to prescribe is down to a few factors. 

There is a fear around certain things, like heart disease or prostate disease. But if guys are truly low in testosterone, their risk for heart disease is probably higher. Too much is a bad thing, but too little appears to be not great either. If you get it in the sweet spot and you replace it enough so that they have a healthy level, the evidence seems to show that it is cardio-protective.

"While GPs can prescribe it, I’m just not sure if they are comfortable with it. You need to have guidelines when you are dealing with something that is a little out of the ordinary. I use the British Society of Sexual Medicine guidelines, which are very good and clear.” 

As a former professional rugby player for Ireland and Leinster, Byrne is well aware of the importance of fitness and nutrition when it comes to testosterone levels.

“It was an easy transition from being a rugby player to working in this area of health. When you get involved in sport and you train, you realise the benefits of it. I’m not saying rugby is the healthiest sport in the world, because it is hard on the body, but training to be fit and strong is good for you. Guys do well when they are in a healthy, controlled training programme, and they also perform better at all levels of life — whether that is physically, intellectually, or sexually. It is basically consistent daily habits that promote positive gene expression — that you are sleeping well, eating well, exercising, managing stress — those four pillars.

"The older I get, the more I train for my mental health than physical health.” 


Anthony, 38, began TRT after experiencing anxiety, depression and panic attacks. This is his story.

“It started when I was quite young, and I lost my mam to cancer. One day, I was inside a fast food place and I couldn’t wait to get out, it was ultimate panic. After that, everything just started snowballing — I couldn’t shift it, I was panicking everywhere I went. 

"My GP said it would pass and gave me some valium, but they didn’t work. I went back and I was put on Seroxat [anti-depressant], that wasn’t working and they upped the dose. I would get a cold sweat every time I went out. I stopped going out and started to put on weight. At the worst of it, I was 22 stone. I wasn’t really living; the anxiety just took over. 

I tried hypnotherapy, psychotherapy, and yoga and nothing was really working.

"Then, one day I saw a newspaper article about [singer] Robbie Williams who said he had cured his depression and anxiety with TRT. That was about two or three years ago. I went back to my own GP about getting TRT, but he said it was stupid. I started researching it online and I found Dr Byrne. 

"They took my blood there … I was called back and I had the testosterone levels of a 60-year-old man. I was given my injection; I was sceptical, but I had nothing to lose. For the first, second, and third week there was nothing, but by the fourth week, it was like a light being switched on inside my head. I felt great for the first time in a long, long time. 

"It was a stepping stone … it’s not a wonder drug, you can’t just take it and sit on your ass and hope for the best, but it gave me confidence. I joined the gym, got a trainer and got my weight down to about 12 stone. I also went back to college and ended up getting a new job. I’ve come off all the medications I was on, and I feel amazing. I get the injection every 10 weeks at the clinic, it costs around €120; every 20 weeks, I have to do blood work. It has been amazing. 

My whole life was on hold, it was horrendous — I was so lucky that I saw Robbie Williams on the front of that newspaper.

Testosterone deficiency has been linked to:

  • Low sex drive
  • Erectile dysfunction
  • Low sperm count
  • Unexplained hair loss
  • Fatigue
  • Insomnia
  • Mood swings
  • Lack of motivation/depression
  • Low bone density
  • Testicular atrophy
  • Increased body fat

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