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.
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.