What causes low testosterone?

Conditions affecting testosterone

Several medical conditions cause low testosterone. These are categorised by where in the system the problem occurs.

Primary hypogonadism

When the testes themselves cannot produce adequate testosterone despite normal brain signalling. Causes include testicular injury or trauma, infection (mumps), surgical removal, chemotherapy effects, radiation therapy, genetic conditions (Klinefelter syndrome). LH levels are high while testosterone is low.

Secondary hypogonadism

When brain signalling to the testes is disrupted. The testes are normal but not receiving signals to produce testosterone. Causes include pituitary tumours, pituitary disorders, head injury affecting the hypothalamus or pituitary, certain genetic conditions. LH and FSH are low alongside low testosterone.

Other medical conditions

Various conditions affect testosterone secondarily. Chronic kidney disease, liver disease, severe heart failure, HIV infection, certain cancers, haemochromatosis (iron overload), various other systemic conditions. The underlying conditions need management alongside any testosterone effects.

Medications

Several medications suppress testosterone. Opioids (long term use), corticosteroids, certain chemotherapy drugs, some seizure medications, certain hormonal medications used for prostate conditions. Speak to your doctor about medications when testosterone is low.

Modifiable factors

Several lifestyle factors significantly affect testosterone. These are often the most addressable causes.

Obesity

Excess body fat is one of the most common modifiable causes of low testosterone. Effects through multiple mechanisms (aromatase, SHBG, inflammation, insulin resistance). Often reversible with weight loss. The most common single modifiable factor for many men.

Poor sleep

Inadequate sleep duration or quality reduces testosterone significantly. Sleep apnoea particularly affects testosterone. Addressing sleep often produces substantial improvement. Sleep is often overlooked as a testosterone factor.

Chronic stress

Sustained stress elevates cortisol which suppresses testosterone. Work stress, financial stress, relationship stress all contribute. Stress management produces hormonal improvements. The effect is often substantial when chronic stress is significant.

Heavy alcohol use

Chronic heavy drinking suppresses testosterone through multiple mechanisms. Moderate occasional drinking has minimal effect. Heavy regular drinking produces measurable reduction. Reducing alcohol often produces hormonal improvement.

Normal versus accelerated

Some testosterone decline is normal ageing. Distinguishing normal from accelerated decline matters.

Normal age related decline

Testosterone declines roughly 1 to 2 percent per year after age 30 in most men. The gradual decline is normal physiology. By age 70, average testosterone is 30 to 50 percent below peak adult levels. Not all age related decline is pathological.

Accelerated decline

Some men show accelerated decline due to lifestyle factors or developing medical conditions. The pattern differs from gradual age related decline. Accelerated decline particularly warrants investigation. The cause may be addressable.

Late onset hypogonadism

Some older men develop hypogonadism that is more than simple age related decline. The condition produces clinical symptoms warranting investigation and treatment in some cases. Speak to your GP about whether your situation reflects normal ageing or pathological decline.

Genetic contributions

Family history affects baseline testosterone and the rate of age related decline. Men whose fathers maintained higher levels often follow similar patterns. The genetic component is real but only part of the picture. Lifestyle factors interact with genetics.

How factors interact

Many men have multiple contributing causes rather than single causes. The combined effects matter.

Combined effects

Obesity plus poor sleep plus chronic stress plus moderate alcohol produces much worse testosterone than any single factor. The cumulative effect of multiple suboptimal factors is often what produces clinically significant deficiency.

Modifiable plus non modifiable

Combination of age related decline (non modifiable) plus modifiable lifestyle factors often produces the apparent low testosterone. Addressing modifiable factors can compensate for some unavoidable age related changes.

Treatment versus causes

TRT addresses low testosterone regardless of cause. Addressing underlying causes when possible produces more comprehensive health improvement. The combination of treatment and cause modification often produces best outcomes.

Systematic approach

Address each contributing factor systematically. Sleep, weight, stress, alcohol, exercise, medications all matter. Single factor focus often misses the comprehensive picture. The systematic approach produces better results.

Keep reading

For symptoms, our Symptoms of Low Testosterone Explained covers what to watch for. What Is Considered Low Testosterone in the UK covers diagnostic thresholds. And Testosterone Replacement Therapy Explained covers treatment.