Low testosterone in men can affect sexual function, energy, muscle, bone health and emotional wellbeing, but symptoms alone cannot confirm a deficiency. Tiredness, low mood and poor concentration have many possible causes. Diagnosis requires a clinical assessment and appropriately timed blood tests before treatment is considered.
In the video below, Dr Maroof discusses why testosterone can change, which symptoms may prompt an assessment, how testing works and when testosterone replacement therapy (TRT) may be considered. If you are concerned about your hormone health, you can arrange a private GP consultation at Zen Healthcare.
Watch: what men should know about testosterone
Dr Maroof explains common symptoms, testing, lifestyle factors and the clinical role of TRT.
What does testosterone do?
Testosterone is the principal androgen hormone in men. It is produced mainly by the testes, under the control of signals from the hypothalamus and pituitary gland in the brain. This communication network is often called the hypothalamic–pituitary–gonadal axis.
Testosterone contributes to sexual development and function, sperm production, muscle mass, bone strength and red blood cell production. Levels vary during the day and are generally highest in the morning, which is one reason the timing of a blood test matters.
Does testosterone always fall with age?
Average testosterone levels tend to fall gradually with age, often from the 30s or 40s, but the pattern differs considerably between individuals. The NHS describes an average decline of about 1% a year and notes that this slow change is unlikely to cause problems by itself.
Clinically significant late-onset hypogonadism is a specific condition, not an inevitable consequence of getting older. It is diagnosed from compatible symptoms together with consistently low testosterone levels—not from age alone.
This is why the expression “male menopause” can be misleading. Men do not experience the same abrupt hormonal change that occurs during menopause. Obesity, type 2 diabetes, acute or chronic illness, poor sleep, pituitary or testicular disorders, previous anabolic steroid use and medicines such as opioids or glucocorticoids can all contribute to lower readings. Identifying the cause matters because some reductions are reversible.
Symptoms of low testosterone in men
Low testosterone can present differently from one person to another. Sexual symptoms tend to be more specific than general symptoms such as fatigue or difficulty concentrating.
- Reduced libido
- Fewer spontaneous or morning erections
- Erectile difficulties
- Reduced muscle mass, strength or exercise capacity
- Increased body fat
- Low energy or persistent fatigue
- Changes in mood, motivation or concentration
- Reduced facial or body hair in some cases
- Reduced bone density or fractures in more marked or prolonged deficiency
- Fertility problems
These symptoms are not unique to testosterone deficiency. Sleep apnoea, anaemia, thyroid disease, diabetes, depression, anxiety, relationship difficulties and medication side effects can produce an overlapping picture. Testosterone is also associated with obesity and metabolic ill health, but this does not mean low testosterone is necessarily the cause or that TRT prevents metabolic syndrome, diabetes or cardiovascular disease.
Can ADAM or AMS questionnaires diagnose low testosterone?
No. Questionnaires such as ADAM (Androgen Deficiency in the Ageing Male) and AMS (Ageing Males’ Symptoms) can help organise a symptom history or monitor changes. However, they have limited specificity and cannot confirm testosterone deficiency. They should not replace a medical history, appropriate examination and blood testing.
How is low testosterone tested?
If symptoms suggest testosterone deficiency, a clinician may arrange a morning, fasting total testosterone test while you are otherwise well. A low result generally needs confirmation on a separate morning. Testing during an acute illness, after inadequate sleep or later in the day may make interpretation less reliable.
UK laboratory guidance emphasises that the diagnosis should combine symptoms with consistently low biochemical results. A single number should not be used for self-diagnosis, and results must be interpreted using the testing laboratory’s method and reference range. You can read the Society for Endocrinology and Association for Laboratory Medicine position statement for more detail.
Depending on the result, symptoms and medical history, further investigations may include:
- Sex hormone-binding globulin (SHBG) and calculated free testosterone when total testosterone is borderline or SHBG may be abnormal
- Luteinising hormone (LH) and follicle-stimulating hormone (FSH) to help distinguish a testicular cause from a problem with hormone signalling in the brain
- Prolactin in selected cases, particularly when a pituitary cause is possible
- Other tests chosen according to symptoms, medicines, medical history and examination findings
Zen Healthcare provides private hormone blood testing with clinical interpretation. The exact tests needed should be selected for the individual rather than treated as a universal panel.
Can lifestyle changes support healthy testosterone levels?
Lifestyle measures support general hormonal and metabolic health, particularly when sleep loss, inactivity or excess body weight may be contributing. Priorities can include:
- Regular resistance exercise alongside suitable aerobic activity
- A balanced diet with adequate energy, protein and micronutrients
- Gradual weight management where clinically appropriate
- Consistent sleep and assessment for suspected sleep apnoea
- Moderating alcohol, stopping smoking and managing long-term stress
- Reviewing medicines and underlying conditions with a clinician
The video mentions magnesium, zinc, omega-3 fatty acids, vitamin D and boron. These should not be described as universal “testosterone boosters”. Correcting an identified deficiency may be appropriate, but supplements do not replace investigation of persistent symptoms and excessive doses can be harmful. Speak to a pharmacist or clinician before taking them, especially if you use regular medicines or have a health condition.
When might TRT be considered?
TRT may be considered when clinically significant symptoms occur alongside consistently low testosterone and reversible causes have been assessed. It is prescription hormone replacement for confirmed hypogonadism—not an anti-ageing shortcut, a bodybuilding aid or a treatment that every man over 40 needs.
Before treatment, an appropriately qualified clinician should review the likely cause, potential benefits, risks, contraindications and personal priorities. Confirmed irreversible hypogonadism may require long-term treatment. Follow-up should assess whether symptoms improve, whether testosterone remains in the intended range and whether adverse effects develop.
TRT risks, monitoring and fertility
TRT is not suitable for everyone. The product and the individual determine the exact precautions, but assessment may include cardiovascular risk, blood pressure, haemoglobin and haematocrit, prostate health where appropriate, breast symptoms, urinary symptoms and sleep apnoea.
Possible adverse effects include acne or application-site reactions, breast tenderness or enlargement, fluid retention and an excessive rise in red blood cells. Gels can transfer testosterone to another person through skin contact if application instructions are not followed. The UK prescribing information for Testogel illustrates why product-specific instructions and regular monitoring matter.
TRT can suppress sperm production
TRT can reduce or stop sperm production while treatment continues and is not a fertility treatment. Anyone hoping to conceive now or in the future should discuss fertility preservation and appropriate alternatives with a specialist before starting treatment.
What about prostate cancer?
Current evidence has not shown a consistent increase in newly diagnosed prostate cancer among appropriately selected men receiving TRT. However, that does not prove zero risk or remove the need for assessment. Known or suspected prostate cancer requires specialist evaluation, and prostate monitoring is tailored to age, symptoms and individual risk.
Frequently asked questions
Can symptoms alone diagnose low testosterone?
No. Symptoms can have many causes. Diagnosis requires compatible clinical features and appropriately collected blood tests showing consistently low testosterone.
What time of day should testosterone be tested?
Testing is generally performed using a morning, fasting sample after a good night’s rest and when you are not acutely ill. A low result usually needs repeating on a separate morning.
Is low testosterone a normal part of ageing?
Testosterone often declines slowly with age, but clinically significant late-onset hypogonadism is not inevitable and should not be diagnosed from age alone.
Can exercise or supplements increase testosterone?
Exercise, sleep and weight management can support overall health and may help when modifiable factors are contributing. Supplements have not been shown to treat hypogonadism unless they address a relevant deficiency.
Does every man over 40 need TRT?
No. Age alone is not an indication for treatment. TRT is considered only after individual assessment of symptoms, repeat hormone results, possible causes, contraindications and personal priorities.
Does TRT affect fertility?
Yes. TRT can suppress sperm production. Anyone planning a family should discuss fertility before beginning treatment and may need specialist advice.
Does TRT cause prostate cancer?
Available evidence has not shown a consistent increase in newly diagnosed prostate cancer in appropriately selected men. This is not a guarantee of zero risk: individual prostate assessment and follow-up remain important.
When should you speak to a clinician?
If persistent changes in libido, sexual function, energy, strength, body composition or mood are affecting your wellbeing, a clinician can help you review possible causes and decide which tests are appropriate.
Zen Healthcare can provide an individual assessment, arrange relevant testing and explain whether lifestyle measures, investigation of another cause or a specialist hormone review may be appropriate. You can also book an appointment online or use the form below.
This article is for general education and does not replace individual medical advice, diagnosis or treatment. Do not start, stop or change prescribed treatment without consulting an appropriately qualified healthcare professional.
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