Testosterone 101: What Every Man Should Know

Testosterone gets plenty of attention, usually alongside promises of more energy, better sex and bigger muscles. That can make a difficult week or a changing body feel like evidence of a hormone problem.

Sometimes low testosterone does need treatment. But tiredness, weight gain and erection difficulties have many possible causes. Understanding the hormone means looking at your symptoms, your overall health and properly timed blood tests together.

What Does Testosterone Actually Do?

Most testosterone in men is produced in the testicles, under instructions from the brain’s hypothalamus and pituitary gland. This signalling system adjusts production according to the body’s needs.

During puberty, testosterone helps deepen the voice, develop facial hair and increase muscle mass. Throughout adulthood, it supports sexual desire, bone strength, muscle maintenance and red blood cell production. Testosterone inside the testicles also helps support sperm production.

It matters for health, but a testosterone result cannot measure your masculinity, confidence or worth. Within the healthy range, a higher number does not automatically mean better health.

Does Testosterone Fall With Age?

Testosterone levels often decline gradually as men get older, although the pattern varies considerably. Some older men maintain healthy levels, while younger men can develop a deficiency.

Unlike menopause, there is no universal, abrupt hormonal transition that every man experiences. Terms such as “male menopause” can therefore be misleading.

Age also brings changes in sleep, medication use, body composition and chronic disease that can influence testosterone. A low reading deserves investigation rather than being dismissed as inevitable ageing or treated automatically.

Which Symptoms Deserve Attention?

A persistent reduction in sexual desire and fewer spontaneous or morning erections can suggest low testosterone. Other possible features include reduced muscle mass, loss of body hair, smaller testicles and fertility difficulties.

A longstanding deficiency can contribute to weakened bones or unexplained anaemia. Very low levels may cause hot flushes.

Fatigue, poor concentration, irritability and low mood can occur, but these symptoms are less specific. Sleep disorders, depression, thyroid problems, medication effects and other illnesses can produce similar experiences.

Erectile dysfunction also needs a broader assessment. Blood vessel disease, diabetes, anxiety and certain medicines can affect erections even when testosterone is normal.

How Is Low Testosterone Diagnosed?

A diagnosis generally requires both compatible symptoms or signs and consistently low testosterone levels. One blood test is insufficient.

Doctors usually request total testosterone on two separate mornings, commonly between 7 am and 10 am, while fasting. Levels fluctuate throughout the day, and illness can temporarily lower them. If you work night shifts, discuss appropriate testing times with your clinician.

South African laboratories commonly report testosterone in nanomoles per litre, or nmol/L. A frequently used international threshold of 300 ng/dL equals approximately 10.4 nmol/L, but guidelines and laboratory methods differ. This is not a universal pass-or-fail number.

If a result is borderline, your doctor may assess free testosterone: the portion not bound to proteins. Changes in sex hormone-binding globulin, or SHBG, can make total testosterone harder to interpret.

Routine testing of every man without symptoms is generally not recommended.

Finding the Cause Matters

Low testosterone, also called hypogonadism, can arise because the testicles produce too little hormone or because the brain’s signals are disrupted.

Possible causes include testicular injury, chemotherapy, inherited conditions and pituitary disorders. Obesity, chronic illness, some medicines and anabolic steroid use can also contribute.

Further blood tests may include luteinising hormone and follicle-stimulating hormone, known as LH and FSH. These help identify where the problem lies. Depending on the findings, your doctor may investigate prolactin or arrange other tests.

Bring a complete list of medicines and supplements to your appointment, including opioid painkillers, corticosteroids and any gym products. Avoid stopping prescribed medication without advice.

What Can Lifestyle Changes Achieve?

When low testosterone is linked to obesity or another reversible contributor, addressing that cause may improve levels and symptoms.

Sustainable weight loss, where appropriate, can help. Regular exercise, including strength training, supports muscle and metabolic health. Adequate nutrition matters too: extreme dieting and excessive training can disrupt hormone production.

Prioritise regular sleep. Loud snoring, breathing pauses and daytime sleepiness warrant assessment for sleep apnoea, which can affect wellbeing and complicate treatment decisions.

These habits support health, but they cannot reliably correct testosterone deficiency caused by permanent testicular damage or a pituitary disorder. Persistent symptoms still need medical assessment.

When Can Testosterone Treatment Help?

Testosterone replacement therapy, or TRT, may help men with confirmed deficiency after the cause and treatment risks have been assessed.

Potential benefits include improved sexual desire, increased lean body mass, better bone density and correction of some cases of anaemia. Effects vary, and different improvements take different amounts of time.

Erection problems may need additional treatment. Improvements in energy, mood and concentration are less predictable.

TRT is not an established treatment for ordinary ageing, a general weight-loss strategy or a guaranteed way to regain youthful performance. The aim is to restore an appropriate hormone level and improve relevant symptoms.

If blood levels improve but symptoms do not, your clinician should reassess the diagnosis and whether treatment remains worthwhile.

Discuss Fertility Before Starting

This is one of the most important treatment conversations.

Taking testosterone from outside the body can suppress the hormonal signals needed for sperm production. Sperm counts may fall dramatically, sometimes to zero, and the testicles can shrink.

TRT can therefore impair fertility even while improving libido. It is not a reliable contraceptive.

Sperm production may recover after stopping, but recovery can take months or longer and is not guaranteed. Tell your doctor if you want children now or in the future. A specialist may recommend approaches that preserve or stimulate sperm production, depending on the cause.

Treatment Requires Ongoing Monitoring

Testosterone can be prescribed in different forms, including injections and gels. The choice depends on medical needs, availability, cost and personal preference.

Gels can transfer testosterone to another person through skin contact. Follow product instructions carefully, including washing your hands and covering the application area.

Possible adverse effects include acne, fluid retention and an increased red blood cell concentration. Testosterone can also raise blood pressure.

A large trial in selected men with confirmed low testosterone found no meaningful increase in major cardiovascular events over the study period. That does not establish safety for every man or settle long-term risks; other adverse events still require consideration.

Monitoring usually includes symptoms, testosterone levels, blood pressure and haematocrit, which measures the proportion of red blood cells. Prostate assessment and PSA testing depend on age, risk and clinical circumstances.

Untreated severe sleep apnoea, elevated haematocrit and certain prostate or cardiovascular conditions may make treatment unsuitable.

Be Sceptical of “Testosterone Boosters”

Over-the-counter boosters often promise more than good evidence supports. “Natural” does not guarantee safety, and some products contain undisclosed ingredients.

Correcting a genuine nutrient deficiency can help health. Taking extra zinc or vitamin D when you already have enough is not a reliable testosterone treatment.

For persistent symptoms, start with a GP. In South Africa, an endocrinologist or urologist may help with complex hormone or fertility concerns. Ask what could explain your symptoms, whether repeat testing is needed and how any proposed treatment will be monitored.