Testosterone and its roles
Testosterone is the main male sex hormone. It is produced mostly by the testes, under the control of signalling hormones from the pituitary gland in the brain, known as LH and FSH.
It contributes to sexual desire and function, sperm production, muscle and bone strength, red blood cell production and body composition, and it plays a part in mood and energy. Levels vary between individuals, through the day, and gradually over a lifetime.
Symptoms associated with testosterone deficiency
Symptoms that may be associated with low testosterone include:
- Reduced sex drive
- Fewer morning erections, or erectile difficulties
- Fatigue and reduced energy
- Low mood, irritability or poor concentration
- Reduced muscle strength and increased body fat
- Reduced body hair, over the longer term
Fatigue and reduced energy
Persistent tiredness is one of the most common reasons men seek a hormone test, yet it is most often explained by something else: poor or insufficient sleep, stress, low mood, anaemia, thyroid problems, diabetes, alcohol, medication or overtraining.
Testosterone treatment is not a remedy for general tiredness, and finding the true cause is what makes a difference.
Changes in libido and sexual function
Low sex drive is one of the symptoms most closely linked with low testosterone, but relationships, stress, mood, fatigue and medications all play a part.
Erectile difficulties more often have a blood vessel, nerve or psychological cause than a hormonal one. Because they can be an early sign of cardiovascular disease, they deserve a proper medical assessment in their own right.
Sleep, weight and metabolic health
Carrying excess weight, type 2 diabetes and obstructive sleep apnoea are all associated with lower testosterone levels. The relationship often works in both directions, and improvements in weight, sleep and activity can be associated with improved levels.
This is why your assessment includes a review of sleep, lifestyle and general health alongside your blood tests.
The importance of accurate diagnosis
Testosterone deficiency is diagnosed only when consistent symptoms occur together with consistently low testosterone levels, confirmed by properly timed blood tests.
Where levels are low, further tests such as LH, FSH and prolactin help to identify why. This matters, because the underlying cause can change what the right next step is.
Why symptoms alone do not establish deficiency
Online questionnaires and symptom checklists can be a reason to get tested, but they cannot diagnose testosterone deficiency. Many men with these symptoms have normal levels, and some men with lower levels have few symptoms.
The role of repeat morning measurements
Testosterone is usually highest in the early morning and falls through the day. Recent food, illness, poor sleep and intense exercise can all lower a result temporarily.
- Samples are taken in the morning, and you may be asked to attend fasting
- A low or borderline result is normally repeated on a separate morning before a diagnosis is made
- Testing is best avoided during or soon after an acute illness
Fertility considerations
Testosterone taken as a medicine signals the body to reduce its own hormone production, which can significantly reduce or stop sperm production. Recovery after stopping can take many months and is not guaranteed.
Risks, contraindications and monitoring
Like any medical treatment, testosterone therapy carries risks and is not suitable for everyone. The decision always rests with the prescribing doctor.
Possible risks
- Raised red blood cell levels (thicker blood)
- Reduced fertility and testicular size
- Acne, fluid retention or breast tenderness
- Worsening of untreated sleep apnoea
- Effects on prostate monitoring
May not be suitable with
- Prostate or breast cancer
- Plans to conceive
- A high red blood cell level
- Untreated severe sleep apnoea
- Uncontrolled heart failure or recent cardiovascular events
Where treatment is started, monitoring typically includes symptom review, testosterone levels, full blood count, blood pressure and, where appropriate, PSA. Checks are usually more frequent in the first year and then generally annual once stable, as directed by the prescribing doctor.