A father's fatigue, low mood and loss of libido was misdiagnosed as depression and anxiety for years - but were really due to his 'critically low' testosterone levels.
When Gordon Russell, from Dumfries, Scotland, first began experiencing symptoms in 2020, he at first put them down to mental health struggles following the death of his father David.
The 46-year-old lung cancer specialist nurse initially believed the exhaustion was linked to sleepless nights after the birth of his daughter Ayda in 2020.
But when the problems persisted for the next two years, Mr Russell found himself going back and forth to his GP - undergoing a range of tests, including blood work for anaemia and thyroid issues, colonoscopies, stool samples and chest X-rays.
However, each test came back normal, leaving the father-of-three scratching his head.
Eventually, Mr Russell was advised by a colleague working in male sexual health to complete the Androgen Deficiency in Ageing Males (ADAM) questionnaire.
The 10-question tool asks about symptoms such as libido and the strength of erections to help identify possible testosterone deficiency.
After new blood test results - and failing the questionnaire 'miserably' - Mr Russell was diagnosed with low testosterone, a condition in which the testicles do not produce enough of the primary male sex hormone, causing many of his symptoms.
Around one million Britons have low testosterone, which usually develops gradually with age, but Mr Russell says there should be greater awareness of the symptoms.
He says he has seen 'huge improvements' since starting daily testosterone replacement therapy (TRT), which restores hormone levels to a healthy range and can reverse many symptoms of the deficiency.
Explaining why he didn't give up before getting his official diagnosis, he said: 'I think it's important sometimes to stand your ground and not just accept things.
'Sometimes people are anxious and depressed, but sometimes they're not, and there needs to be more investigation around this area.
'When men get to a certain age, this could be a real issue. That's where I would like to see things change more.'
Mr Russell said he has always been 'relatively fit and healthy', with no underlying health conditions, but felt his body changing after turning 40.
The nurse couldn't understand why he felt so chronically fatigued, and noticed that he'd begun gaining unusual levels of weight, making him extremely self-conscious.
He added: 'My libido decreased as well and my general interest in everything was gradually starting to deteriorate.
'So I was grumpy and my mood was off. I felt like I was constantly correcting the kids for things and I just had a shorter fuse than normal.'
Doctors suggested that he had anxiety and depression but he felt it was not true.
However, his mood plummeted even further when his father died aged 70, a year after being diagnosed with prostate cancer.
He said: 'That's when everything really started to slump and I lost interest in things like (gym) training.
'I was just exhausted and I was reaching the point of being burnt out. I was physically and emotionally at the lowest point I think I've ever been.'
At this point, Mr Russell's doctor suggested again that he may have depression, but he continued to explore other options.
He then came across research about low testosterone and recognised many of the symptoms including mood swings, irritability, loss of muscle mass, reduced exercise capacity, fat redistribution and lack of enthusiasm.
After discussing with his colleague, he completed the ADAM questionnaire, which his wife Sarah helped fill out so she could be 'more honest' about changes in libido and sex drive.
He said tests confirmed his testosterone levels were 'awful' and 'critically low'.
By early 2025, Mr Russell began TRT through the NHS, but found the initial three-monthly injections caused mood fluctuations. After finding the health brand Voy on social media he decided to switch.
Now, he says: 'My focus, my energy, my libido - everything's back to where it should be, rather than bouncing up and down all the time.'
Mr Russell said he has experienced side effects of testicular atrophy - when the testicles decrease in size - small acne breakouts on his back and shoulders, and light shedding of hair, so he takes another medication called HCG to help with fertility.
He said he is regularly monitored and, if he has any concerns, consultants are readily available.
Today, Mr Russell said he has more energy for his children, his libido is 'better than normal' and he has been able to maximise his gym training and nutrition so he is 'more proud' of himself physically.
He added: 'I want to make the message clear that it's OK to say that something's not right and for men to openly talk about things like libido, erections and energy to remove that stigma from it.'