Causes Of Low Testosterone in Men

Contrary to common belief, testosterone deficiency isn’t limited to older men.  It can affect males of all ages, including teenagers, young adults, and even children, depending on the underlying cause. While age-related decline is common, many other factors can contribute to low testosterone levels. Understanding the root causes is the first step towards proper diagnosis and effective treatment.

The Impact of Ageing and Andropause

It’s normal for testosterone levels to decline gradually with age. This age-related reduction is sometimes referred to as andropause (or male menopause).  After peaking in their late teens, most men's testosterone levels tend to remain steady through early adulthood.

This changes around the age of 40,when levels begin to fall, typically at a rate of 1.2% to 2% per year. By the time men reach their 70s or 80s, testosterone levels are often significantly reduced—though symptoms may begin as early as midlife.

Causes of Testosterone Deficiency Advice from Urban TRT Ireland

Primary Versus Secondary Hypogonadism

Low testosterone is medically known as hypogonadism, and is classified into two types:

  • Primary hypogonadism occurs when the testes fail to produce adequate testosterone due to a direct problem with the testes themselves.
  • Secondary hypogonadism results from a disruption in the brain’s hormonal control system.  In particular, the hypothalamus or pituitary gland within the brain, which regulate testosterone production in the testes.

Causes Of Primary Hypogonadism

Primary hypogonadism can be congenital (present from birth) or it can be caused by an illness or accident later in life. Common causes include:

Genetic conditions:

  • Klinefelter’s Syndrome
  • Noonan Syndrome
  • Undescended testicles
  • Haemochromatosis
  • Ambiguous genitalia

Acquired disorders:

  • Physical trauma or infection affecting both testicles
  • Mumps affecting the testes
  • Damage from cancer treatments such as chemotherapy or radiotherapy

Causes Of Secondary Hypogonadism

This form of testosterone deficiency is due to dysfunction in the hypothalamus or pituitary gland. Common causes include:

Medical conditions and infections:

  • Pituitary gland disorders (tumours, kidney failure, substance abuse)
  • Inflammatory diseases such as sarcoidosis, tuberculosis or histiocytosis
  • Kallmann Syndrome
  • HIV/AIDS
  • Liver cirrhosis
  • Type 2 diabetes

Lifestyle and external factors:

  • Obesity
  • Anabolic steroid use
  • Chronic opioid use
  • Alcohol and drug abuse
  • Malnutrition or eating disorder
  • Prolonged physical or emotional stress

Can I Have Both Primary And Secondary Testosterone Deficiency?

In some cases, men may experience a combination of both primary and secondary causes—this is known as mixed hypogonadism. It becomes more common with age, during long-term glucocorticoid therapy, or in individuals with chronic conditions such as:

  • Thalassemia
  • Sickle cell disease
  • Alcohol dependence

What Should You Do Next?

If you're experiencing symptoms of low testosterone—such as fatigue, low libido, or muscle loss—it’s important to seek medical advice. A blood test and consultation with a specialist can help determine the cause and guide you toward the most effective treatment.

At Urban TRT Ireland, we provide fast, discreet, and expert care. Book a simple at-home blood test today and take the first step toward restoring your health and wellbeing.