Understanding Testosterone and How It Affects Health

When it comes to male health and hormones, testosterone gets a lot of attention. Its role in the body, however, is often misunderstood and most are not aware that it has a wide range of effects.

Testosterone is an integral component in sexual health, plays a role in maintaining bone density and muscle mass and even has an effect on behavior. While most men have enough testosterone, low levels can lead to conditions such as hypogonadism which, in certain cases, may be treated with hormone therapy.

Here we look at testosterone, how it affects the body, what are the most common causes of low levels and how this is treated.

How testosterone levels change with age

What Is Testosterone?

Testosterone is a hormone found in both sexes but in higher levels in males. It is often referred to as the sex hormone and is produced in the testes in men and the ovaries in women.

The amount of testosterone produced in the body is dictated by the hypothalamus in the brain which sends messages to the testes via the pituitary gland. Testosterone levels rise and fall over time for a variety of reasons.

For example, if someone is sexually active or taking part in competitive physical activity there is likely to be a rise in levels. If they are inactive or lead an unhealthy lifestyle, levels can drop.

How Testosterone Affects the Body

Testosterone plays a role in development even before a male child is born. In the womb, it’s involved in the growth of the penis and testicles. As a child reaches puberty, the hormone is integral in developing male characteristics such as hair growth, deepening of the voice and the libido.

  • Testosterone is also associated with behaviours such as aggression and dominance which are higher in males.
  • It engages with neurotransmitters that promote muscle development and causes protein synthesis.
  • Bone density is also increased by higher levels of testosterone as male children move towards adulthood and is maintained during adulthood.
  • Men burn fat more efficiently than women because of their higher level of testosterone.

Testosterone also plays a role in red blood cell production and has a beneficial effect on the heart.

Testosterone effects infographic

What Happens to Testosterone Levels with Age?

From birth, testosterone levels rise, surging during the teenage years where many bodily changes take place. This continues to the early 20s when levels remain relatively stable.

From the age of 30 onwards, however, testosterone levels in men begin to decline naturally by about 1% each year. As an individual gets older, they may experience changes such as putting on more fat and noticing a reduced sex drive.

How Common is Low Testosterone and What Causes it?

A study by the University of Michigan found that as many as 30.8% of men had some level of testosterone deficiency. As we might expect, this was more common in older men. Individuals with low testosterone were also more likely to have more than one chronic illness.

While age is one of the main determining factors for a reduction in testosterone levels, lifestyle choices can also play a role. Poor diet choices, lack of exercise, smoking and excess alcohol may all affect hormone levels.

Health problems such as injury to the testicles, chronic illnesses, cancer treatment and certain medications can also have an impact.

Testing Testosterone

Low testosterone can lead to a range of symptoms, including loss of muscle mass, more fat development, lower bone density, loss of libido and emotional changes. A physician will look at these in detail and carry out a physical examination when making their diagnosis.

Blood tests can be used to determine testosterone levels but the health care team will look at other possibilities such as illness and disease and rule them out as a causal mechanism.

How Low Is Too Low?

The lower limit for testosterone is around 300 ng/dL with the maximum at 800. Levels of testosterone vary considerably over time and it’s usually only a level of about 200 ng/dL or below where concerns will be raised and hormone replacement considered.

Low Testosterone Treatment

Testosterone replacement therapies are not generally the first approach used by physicians. If someone is not exhibiting symptoms but registers low levels, there may be other causes that are more easily remedied.

This could mean, for example, someone losing weight and improving their activity and dietary intake to boost testosterone levels naturally.

  • Testosterone therapy is typically not used for general low levels caused by ageing.
  • While it is a treatment that is often used with older individuals, it can be employed for younger men who are having trouble starting a family.
  • The treatment can be delivered in a variety of ways including injection, skin patch, capsule and gel. Symptoms should improve over four to six weeks.
  • There can be some side effects associated with the therapy including sleep apnea and, in some cases, lower sperm levels and shrinkage of the testes.

Testosterone replacement therapy should never be undertaken without medical advice. Individuals need to discuss testosterone treatment through with their physician as it may not be the appropriate approach for their condition.