Testosterone is the key hormone for male health. While it is often associated with sexuality, its action is actually systemic: regulating energy, muscle mass, bone mineralization, mood, and metabolism.
From the age of 30 to 40, circulating levels physiologically decline by approximately 1% per year. In some cases, this decline becomes more pronounced and leads to a significant deficiency (hypogonadism), with a direct impact on quality of life and fertility.
What is the purpose of testosterone in men? Secreted primarily by Leydig cells in the testicles (under the control of the pituitary gland), testosterone plays a role at several levels:
- Sexual sphere: maintenance of libido, quality of erections and support of spermatogenesis.
- Body composition: preservation of muscle mass, regulation of fat mass and bone strength.
- Cognitive and psychological functions: energy level, motivation, mental clarity and mood stability.
What are the signs of a testosterone deficiency? A low level doesn’t only result in sexual problems. The most common clinical manifestations include:
- Chronic fatigue and an unexplained loss of vitality.
- A marked decrease in sexual desire and less frequent or less rigid morning erections.
- Progressive muscle loss associated with abdominal fat gain.
- Sleep disturbances, irritability, or “brain fog”.
- A decrease in fertility (oligospermia, alteration of sperm parameters).
Since these symptoms are non-specific, they are not sufficient to make a diagnosis without biological testing.
How to diagnose a hormonal deficiency? The diagnosis is based on the strict correlation between clinical symptoms and biological data:
- Morning fasting blood test: total testosterone (and ideally bioavailable or free testosterone, associated with SHBG) should be measured between 8 a.m. and 10 a.m.
- Biological confirmation: a second test is systematically carried out a few weeks later to confirm the anomaly.
- Etiological investigation assessment: measurement of gonadotropins (LH, FSH), prolactin and complete metabolic assessment (blood glucose, lipid profile, liver function tests).
What are the possible causes?
- Primary testicular involvement: history of cryptorchidism, trauma, chemotherapy or presence of a varicocele .
- Metabolic factors and lifestyle: overweight/visceral obesity, metabolic syndrome, type 2 diabetes, obstructive sleep apnea (OSA), chronic stress and sedentary lifestyle.
- Central origin (hypothalamic-pituitary): pituitary adenoma, hyperprolactinemia or prolonged use of certain treatments.
What are the treatment options? The treatment is always personalized and tailored to the cause and the desire for a child:
- Optimizing lifestyle habits: regular physical activity (especially muscle strengthening), dietary rebalancing, and addressing any sleep apnea syndrome. This often helps restore sufficient endogenous production.
- Treatment of a urological cause: in the case of associated clinical varicocele, a cure by subinguinal microsurgery often allows a significant increase in natural testosterone levels.
- Hormone replacement therapy (HRT): indicated in cases of proven hypogonadism resistant to lifestyle and dietary measures (transdermal gels, intramuscular injections). Caution: exogenous testosterone blocks the gonadotropic axis and stops sperm production; it is therefore contraindicated in men planning to father children in the short or medium term.
When to consult? A consultation with a specialist in andrology is recommended in cases of persistent fatigue associated with decreased libido, established erectile dysfunction, or difficulties with fertility in the context of being overweight or having a varicocele. A targeted assessment helps identify the cause of the problem and implement an appropriate medical solution.
Dr Davy Benarroche — Urologist and andrologist surgeon in Paris, specializing in men’s health and fertility.