Information for patients

What is low testosterone?

What is testosterone?

Testosterone is an essential male hormone produced in the testes that plays a crucial role in the health and well-being of our bodies. Testosterone is responsible for typical male sexual characteristics and is required by all men for a healthy life physically and psychologically. Figure 1 shows the different actions of Testosterone in an adult male.
Figure 1: Actions of Testosterone in an adult male
vergrößern Figure 1: Actions of Testosterone in an adult male

What is low Testosterone?

Low testosterone (the medical term is hypogonadism) simply means having a very low testosterone level. It happens when the testes do not function normally or when internal hormone production is out of balance. Low testosterone can occur in men of any age. However, there is a progressive decline in testosterone levels as men age.

Although not a common condition, it is hard to say exactly how many men have low testosterone. Doctors believe that 5 in 1,000 men are living with some form of hypogonadism. The number of men with low testosterone increases with age and as many as 1 in 5 European men over the age of 50 has moderate or severe symptoms of testosterone deficiency.

What causes low testosterone?

There are two main types of low testosterone condition, and each has its own cause: these are referred to as primary and secondary hypogonadism. In addition to that there is another type of low testosterone that appears in aging men. This is considered as a combination of primary and secondary hypogonadism.

Primary Hypogonadism: In primary hypogonadism, low testosterone is caused by a problem with the testes.

Secondary hypogonadism: Secondary hypogonadism occurs when the complex hormonal system responsible for producing male sex hormones goes out of balance or breaks down.

Late-onset hypogonadism: Late-onset hypogonadism refers to low testosterone associated with advancing age. Men normally experience some decline in testosterone level as they age due to reduced function of the testes and the complex hormonal system. This decline may be accelerated by poor health, and some men’s testosterone levels may fall too far.

About 20% of men older than 60 years and 30–40% of men older than 80 years have testosterone levels below the physiological range for younger men.

Age related decline in testicular function

What are risk factors for low testosterone?

Risk Factor Description
Klinefelter's syndrome A genetic deficiency in testosterone production. Affects between 1 in 500 and 1 in 1000 men.
Injury to the testes The testes are prone to injury because they hang outside the body and are not protected by bone or muscle. Damage to testes can cause reduced testosterone production
Un-descended testes The testes develop within the abdomen and descend into the scrotum shortly before birth. In some cases one or both of the testes may not descend at birth (this happens in about 1 in 4 boys born prematurely and 1 in 20 boys born at term). The condition usually corrects itself naturally within the first year of life but if not corrected in early childhood, the testes may not develop properly.
Mumps orchitis Sometimes a mumps infection will involve the testes as well as the saliva glands. If this happens during adolescence or adulthood, long-term damage may occur that affects testosterone production.
Cancer and cancer treatment Cancer of the testes or pituitary tumours can lead to low testosterone. Chemotherapy or radiation therapy can also interfere with testosterone production
Hormone system imbalance Kallmann syndrome involves abnormal development of the hypothalamus and is a risk factor for low testosterone. Pituitary disorders can impair the release of hormones affecting normal testosterone production.
Chronic illnesses Chronic illnesses such as liver or kidney disease, diabetes, metabolic syndrome and rheumatoid arthritis may be risk factors for low testosterone.

In some instances it is not clear whether the chronic illness is a cause or a consequence of low testosterone.
Normal aging Men normally experience some decline in testosterone level as they age.
Haemochromatosis Haemochromatosis is a genetic disorder that causes the body to absorb too much iron from the diet. This iron can be deposited in various body organs including the hypothalamus, pituitary and testes. It is now recognized as a common disorder and 1 in 200 people of northern Europe may be at risk of developing iron overload.

How can low testosterone be treated?


Last updated: 2018
G.MKT.GM.MH.02.2018.0506