Male testosterone deficiency: causes, symptoms and treatment

What exactly is testosterone deficiency?

Testosterone is the primary male sex hormone. Beyond driving libido, it helps build muscle and bone density, regulates body fat distribution and influences both mood and focus. When testosterone levels remain consistently low and certain symptoms appear, doctors refer to the condition as hypogonadism, or male testosterone deficiency. While the condition can feel unsettling, a medical check-up will quickly provide clarity.

What are the symptoms of testosterone deficiency?

Testosterone deficiency can present in various ways. Some signs appear early on, while others develop gradually over months or even years. Typical early indicators include:

Physical changes linked to long-term deficiency

A persistent testosterone deficit can trigger several bodily changes over time:

• loss of muscle mass and physical strength
• increase in body fat – particularly around the abdomen
• reduced bone density, leading to a higher risk of osteoporosis
• development of male breasts (gynaecomastia)
• slower beard growth or hair loss
• shrinking of the testicles
• reduced fertility

Testosterone deficiency and mental well-being

Low testosterone often affects mental well-being, as the brain contains numerous receptors that respond directly to the hormone. Testosterone also influences neurotransmitters like serotonin and dopamine, which regulate mood. Many men with low testosterone report psychological symptoms such as fatigue, exhaustion, mood swings, low mood, irritability, and difficulties with memory and concentration.

What else could be causing these symptoms?

Myths and half-truths abound when it comes to testosterone. Many symptoms are non-specific and may point to entirely different conditions – for example, chronic stress alone can cause a decline in energy levels and libido. Only a medical check-up and blood tests can provide a definitive diagnosis. Similar complaints can also stem from:

• sleep deprivation and sleep disorders
• type 2 diabetes and other metabolic conditions
• depression or other psychological distress
• thyroid disorders
• chronic stress
• metabolic syndrome (a combination of obesity, high blood pressure, poor lipid profiles and impaired blood sugar control)

What causes testosterone deficiency?

Medical professionals categorise testosterone deficiency into 3 types:

1. functional
2. primary
3. secondary

Each form has different underlying causes. By far the most common form of testosterone deficiency is functional hypogonadism.

Functional hypogonadism

Functional deficiency frequently occurs alongside obesity, metabolic disorders like type 2 diabetes, various comorbidities, general poor health and advancing age. An unhealthy lifestyle – marked by chronic stress, lack of sleep and substance misuse – can also drive testosterone levels down. Functional hypogonadism is often reversible once the underlying health factors improve. This potential for recovery is why doctors classify it as "functional" rather than primary or secondary.

Age-related testosterone decline

From around age 30 to 40, a man's testosterone levels drop naturally by roughly 1-2% each year. In healthy men, this gradual decline is usually minor and causes no symptoms. A clinically significant deficiency is therefore neither normal nor an inevitable part of getting older. However, when coupled with factors like excess weight, diabetes or chronic illness, ageing can accelerate the drop. In addition, some men aged between 45 and 65 also report similar symptoms colloquially referred to as the "male menopause". However, these complaints aren't necessarily driven by low testosterone.

Primary hypogonadism

In primary testosterone deficiency, the root problem lies in the testes. They fail to produce sufficient testosterone and, in most cases, sperm production drops too. Potential causes include congenital conditions like Klinefelter syndrome, testicular injury, mumps orchitis (inflammation of the testes following a mumps infection), chemotherapy, radiotherapy or undescended testicles.

Secondary hypogonadism

Secondary testosterone deficiency stems from issues in the pituitary gland (a hormone gland at the base of the brain) or the hypothalamus (the part of the brain that connects the nervous and endocrine systems). These are responsible for signalling the testes to produce testosterone, but fail to do so effectively. Underlying causes include pituitary tumours, elevated prolactin levels, certain medications like opioids, or rare genetic disorders.

What to do if you have testosterone deficiency?

Depending on the form, there is a lot men can do to improve their situation. However, symptoms alone don't constitute a diagnosis – only a medical examination and blood test can confirm whether you genuinely have testosterone deficiency and what is causing it.

Steps you can take yourself

Lifestyle changes make a substantial difference, especially when dealing with functional hypogonadism. The following measures have the strongest scientific backing and offer wide-ranging benefits for your overall health:

When should you get your testosterone levels tested?

Testing is worthwhile if several key symptoms appear together and persist over time – for instance, a combination of low libido, erectile dysfunction and profound fatigue. By contrast, an isolated symptom doesn't justify jumping to conclusions or self-diagnosing. Your first step should always be to contact your FD or a specialist consultant.

What does the diagnosis involve?

1. Morning blood test: Because testosterone levels fluctuate throughout the day and are highest in the morning, blood samples are typically drawn on an empty stomach and before 11.00 am.
2. Confirmation via a second reading: Since a single test can be affected by stress or how you feel on the day, medical authorities recommend confirming any low reading with a second test on a different day.
3. Checking LH and FSH levels: Measuring these hormones helps pinpoint whether the issue originates in the testes (primary) or higher up in the hormonal control system (secondary).
4. Spotting functional deficiency: If LH and FSH fall within normal ranges and there is no structural damage to the testes or pituitary gland, the likely outcome is a functional deficiency – particularly if accompanied by excess weight, type 2 diabetes or other comorbidities.
5. Further investigations: Depending on initial findings, additional tests may follow, such as an imaging scan of the pituitary gland or a fertility test.

LH and FSH – what are they?

Luteinising hormone (LH) and follicle-stimulating hormone (FSH) are produced in the pituitary gland and direct testicular function: LH triggers testosterone production, while FSH drives sperm development. If the testes themselves are impaired, LH and FSH levels rise as the body tries to compensate. If the issue lies in the pituitary gland or hypothalamus instead, LH and FSH tend to remain low or not abnormal despite deficient testosterone levels.

When is testosterone therapy called for?

Testosterone replacement therapy comes into question once a clinical deficiency is confirmed. However, it isn't suitable for everyone and must always be carried out under medical supervision with regular follow-up checks.

Particular caution is required:

• If you're planning a family: Administering external testosterone can suppress natural sperm production, as the body registers sufficient hormone levels and shuts down testicular output.
• With certain prostate conditions or elevated PSA levels: Testosterone can fuel the growth of hormone-dependent prostate tissue, making a prior urological assessment advisable.
• In untreated, severe sleep apnoea: Testosterone can disrupt breathing patterns during sleep and worsen existing apnoeic episodes.
• With elevated haematocrit (blood density) or erythrocytosis: Therapy stimulates red blood cell production and can thicken the blood further, increasing the risk of thrombosis.
• With existing cardiovascular disease or a high risk of thrombosis: Because testosterone affects factors like blood composition, a thorough clinical evaluation and ongoing monitoring are particularly required.

Treatment options for testosterone replacement therapy

Several administration routes are available: daily gels or patches applied to the skin, short-acting injections every few weeks, and long-acting depot injections given every few months. Tablets exist as well, though they play a minor role in clinical practice. The right choice depends on the underlying cause, your daily routine and personal preference.

Potential side effects of testosterone replacement therapy

Alongside higher-risk complications that demand caution, testosterone replacement therapy can cause other, generally harmless side effects:

• increased acne and oily skin
• benign enlargement of breast tissue (gynaecomastia)
• local site irritation and discomfort from injections, or skin redness from gels
• occasional spikes in irritability and mood swings