Key Points
- Testosterone naturally declines with age — this is normal
- True testosterone deficiency (hypogonadism) is less common than many think
- Many symptoms attributed to "low T" have other causes
- Testosterone replacement is only appropriate for men with proven deficiency
- Buying testosterone online without a prescription is illegal and dangerous
What Does Testosterone Do?
Testosterone is the main male sex hormone. It's responsible for:
- Development of male characteristics during puberty
- Muscle mass and strength
- Bone density
- Sex drive (libido)
- Sperm production
- Red blood cell production
- Fat distribution
- Mood and energy
Testosterone levels naturally decline by about 1-2% per year after age 30. This is normal and doesn't usually cause problems.
Symptoms of Low Testosterone
True testosterone deficiency (hypogonadism) can cause:
Sexual Symptoms
- Reduced sex drive
- Erectile dysfunction
- Fewer spontaneous erections
- Reduced fertility
Physical Symptoms
- Loss of muscle mass
- Increased body fat
- Decreased bone density
- Fatigue
- Breast tissue development
Mental Symptoms
- Low mood
- Poor concentration
- Reduced motivation
- Sleep disturbances
Other Signs
- Hot flushes
- Reduced body hair
- Small testicles
- Anaemia
Important Note
These symptoms are very non-specific. They're commonly caused by:
- Depression and anxiety
- Poor sleep
- Obesity
- Diabetes
- Other medical conditions
- Normal ageing
Don't assume your symptoms are due to low testosterone without proper testing.
Causes of Low Testosterone
Primary Hypogonadism
Problem with the testicles
- Klinefelter syndrome
- Undescended testicles
- Testicular injury
- Cancer treatment
- Mumps orchitis
Secondary Hypogonadism
Problem with pituitary/hypothalamus
- Pituitary tumour
- Obesity
- Type 2 diabetes
- Opioid use
- Steroid use
- Chronic illness
Testing for Low Testosterone
If your GP suspects low testosterone, they'll arrange blood tests:
How Testing Works
- Blood test in the morning — Testosterone is highest early in the day (before 11am)
- Fasting may be required — Food can affect results
- Two tests needed — One low result isn't enough; it needs confirming
- Other hormones checked — LH, FSH, prolactin to find the cause
Normal Testosterone Levels
There's debate about the exact cut-off, but generally:
- Normal: Above 12 nmol/L (some say 10-12)
- Borderline: 8-12 nmol/L
- Low: Below 8 nmol/L
But levels need to be interpreted alongside symptoms. A man with borderline levels and no symptoms may not need treatment.
Things That Lower Testosterone Results
These can give falsely low results:
- Being unwell
- Poor sleep the night before
- Testing in the afternoon
- Obesity
- Some medications
This is why testing is repeated and done properly.
Treatment
Testosterone replacement therapy (TRT) is only appropriate for men with:
- Confirmed low testosterone (on two morning samples)
- Symptoms consistent with testosterone deficiency
- No reversible cause that should be treated first
Forms of Testosterone Replacement
- Gel (Testogel, Tostran) — Applied daily to skin. Most common.
- Injections — Every 2-3 weeks or every 10-14 weeks (long-acting)
- Patches — Applied daily
- Implants — Pellets inserted under the skin every 4-5 months
Before Starting TRT
Your doctor should:
- Check PSA (prostate-specific antigen)
- Assess prostate with digital rectal exam
- Check blood count (haemoglobin/haematocrit)
- Discuss fertility — TRT reduces sperm production
- Discuss risks and benefits
Monitoring on TRT
Regular follow-up includes:
- Testosterone levels
- PSA and prostate assessment
- Blood count (to check for polycythaemia)
- Symptom review
Risks of Testosterone Therapy
- Polycythaemia — Blood becomes too thick, increasing clot risk
- Prostate concerns — May stimulate prostate growth; contraindicated with prostate cancer
- Infertility — TRT suppresses sperm production
- Acne and oily skin
- Sleep apnoea worsening
- Cardiovascular risk — Uncertain; needs monitoring
What About "Low T" Clinics?
Many private "men's health" or "TRT" clinics have emerged. Be cautious:
- Some may prescribe testosterone without proper assessment
- They may use lower thresholds for "low" testosterone
- Ongoing monitoring may be inadequate
- It can be expensive
If you genuinely have testosterone deficiency, the NHS can provide treatment with proper monitoring.
Buying Testosterone Online
This is illegal and dangerous.
- It's a controlled substance in the UK
- Products may be fake or contaminated
- There's no monitoring for side effects
- Self-medicating can cause serious harm
Natural Ways to Support Testosterone
Before considering TRT, these lifestyle factors can help optimise testosterone:
- Lose weight — Obesity lowers testosterone; losing weight can raise it
- Exercise — Especially resistance training
- Sleep well — Poor sleep significantly lowers testosterone
- Reduce stress — Chronic stress increases cortisol, which lowers testosterone
- Limit alcohol — Excess alcohol reduces testosterone
- Eat well — Adequate protein, healthy fats, zinc, and vitamin D
These won't "cure" true hypogonadism, but they can help borderline levels and improve symptoms regardless of testosterone level.