Low Testosterone in Men: Symptoms, Causes, Diagnosis and Treatment

Low testosterone, also called male hypogonadism, is a medical condition in which the body does not produce enough testosterone and this causes compatible symptoms or signs. It is not diagnosed from tiredness alone, an online questionnaire or one unexpectedly low blood result.

Sexual symptoms are among the most informative. These include reduced sexual desire, fewer morning or spontaneous erections and erectile difficulties. Low energy, low mood and poor concentration can occur, but they are common in many other conditions.

What are the symptoms of low testosterone?

Possible features include:

• lower sexual desire;
• fewer morning or spontaneous erections;
• erectile dysfunction;
• reduced fertility;
• loss of body or facial hair;
• reduced muscle mass or strength;
• increased body fat;
• hot flushes or sweats in more marked deficiency;
• low bone density or fractures;
• tiredness, poor motivation or reduced concentration; and
• low mood or irritability.

The pattern, severity and timing matter. A man with several new sexual symptoms and repeatedly low morning testosterone results has a different clinical picture from someone who is tired after prolonged stress but has normal hormone results.

Is the “male menopause” the same thing?

Not usually. The phrase “male menopause” suggests a sudden, universal hormonal change like menopause in women. Testosterone normally falls gradually with age, and many midlife symptoms are more strongly related to sleep, stress, anxiety, depression, alcohol, inactivity, weight or relationship difficulties.

Late-onset hypogonadism is a specific medical diagnosis. It requires symptoms plus consistently low testosterone after other explanations have been considered.

What causes low testosterone?

Clinicians broadly consider three patterns.

Primary hypogonadism

The testes are not producing enough testosterone, so LH and FSH from the pituitary are often raised. Causes include some genetic conditions, previous testicular injury, infection, chemotherapy or radiotherapy.

Secondary hypogonadism

The pituitary or hypothalamus is not sending an adequate hormonal signal to the testes, so LH and FSH may be low or inappropriately normal. Causes can include pituitary disease, raised prolactin, some genetic conditions, previous head injury, opioids and other medicines.

Functional suppression

Testosterone can be suppressed without permanent structural damage to the hormone system. Obesity, poorly controlled diabetes, severe illness, sleep problems, undernutrition, excessive exercise and some medication can contribute. Treating the driver may improve both symptoms and testosterone.

Age alone is not a diagnosis, and a low result should not automatically be attributed to ageing.

How is low testosterone diagnosed?

A sound assessment has four parts:

1. Compatible symptoms and signs. Sexual symptoms carry particular weight, but the whole picture matters.
2. Correctly timed total testosterone. Testing is normally done fasting in the morning, usually between 7am and 10am.
3. Confirmation. A low result should be repeated on a separate morning before treatment is considered.
4. Cause and context. SHBG, calculated free testosterone, LH, FSH, prolactin and selected general health tests may help explain the result.

Current European guidance uses a total testosterone threshold of 12 nmol/L in the appropriate clinical setting, while UK guidance also recognises a lower-result range and a grey zone. These thresholds are aids to judgement, not automatic prescribing rules. Laboratory range, symptoms, SHBG, illness, medication and fertility plans all affect interpretation.

Can weight loss or lifestyle changes improve testosterone?

They can, particularly when low testosterone is functionally associated with excess weight, metabolic disease, poor sleep or heavy alcohol use. Useful priorities may include:

• gradual, sustainable weight loss where appropriate;
• resistance and aerobic exercise;
• adequate sleep and assessment for sleep apnoea;
• reducing excess alcohol;
• stopping smoking;
• improving diabetes and cardiovascular risk; and
• reviewing contributing medication with the prescriber.

This is not a suggestion that every symptom can be fixed by lifestyle. It is part of treating causes and improving safety, whether or not medical treatment is later used.

When is testosterone treatment considered?

Testosterone replacement may be discussed when:

• compatible symptoms are significant;
• low testosterone is confirmed on appropriately timed tests;
• reversible or alternative causes have been considered;
• expected benefits and uncertainties are understood;
• contraindications and cardiovascular risk have been assessed; and
• the man does not currently want to preserve fertility.

Potential benefits can include improvement in sexual symptoms, body composition, anaemia or bone health in appropriately selected men. Benefit is not guaranteed, and nonspecific symptoms may not improve if testosterone was not their cause.

Why do fertility plans matter?

External testosterone suppresses LH and FSH and can markedly reduce sperm production. It is not a fertility treatment and is contraindicated when a man is actively trying to conceive. Men who want children now or in the future should raise this before any treatment so that alternatives or specialist fertility advice can be considered.

Who may not be suitable for testosterone treatment?

Important contraindications or cautions include active prostate or male breast cancer, a high haematocrit, uncontrolled heart failure, severe untreated urinary symptoms, recent or unstable cardiovascular illness, thrombosis risk and untreated severe sleep apnoea. The exact decision is individual and may require specialist input.

What monitoring is needed?

Treatment should have a clinical aim and a safety plan. Monitoring commonly includes symptoms, testosterone level and haematocrit at around three, six and twelve months, then at least annually once stable. Prostate assessment and PSA monitoring are based on age, risk and the agreed pathway.

A haematocrit above 54% requires prompt clinical action, which may include adjusting or pausing treatment and investigating contributing factors. Monitoring is not optional.