Testosterone is a part of the complex endocrine system., When it functions properly in the body, the likelihood of ill-health is reduced. It is responsible, at least in part, for lean body mass,²³ muscle,¹³⁰ hair, bone strength,^{103 39}testicular or ovarian function, mood, cognitive function¹¹³ and long term health. ¹⁵²¹³⁸

For men, Testosterone plays a vital part in fertility, in conjunction with the Leydig cells in the testicles. The level varies slightly over a day, due, in part, to activity, so men's levels tend to be at their highest after a good night's sleep.
For women, Testosterone plays a vital role in ovarian health,⁸⁹ and is now shown to have wide swings during childbirth¹³⁹ and the menstrual cycle. It is said to influence libido and mood in women^{140 79}Post-menopausal women are at risk of Testosterone depletion.⁶⁶

Testosterone's "central command", is the Pituitary gland, which is a part of the extremely complex "Hypothalmic-Pituitary axis", housed in the brain. The endocrine system appears to be very delicate and the body seems to respond negatively to imbalance in the aforementioned axis.

A number of interacting "chemicals" play a vital part in the "supply and demand" chain. Excess Testosterone leads to negative imbalance elsewhere. Similarly, a deficiency in Testosterone leads to subtle side effects, becoming increasingly more obvious, with elevated risk of disease, if either remain undetected in the long-term.

¹ Recent animal research suggests various factors may affect the foetus as it develops in the womb, leaving the newborn Hypogonadal. ¹⁵⁸ Genetic malformations¹²²¹⁵²cause Hypogonadism from birth, leaving the undetected baby, as most remain through to adulthood, "behind the eight ball". There are indicators in newborn's,⁸²³ which can help detect potential Hypogonadism.²⁵²⁹ Similarly, there are tests and treatments suggested for every important stage of development insofar as Testosterone is concerned.

Excess testosterone in the body is also negative to health ⁷⁴.

Opinion
The importance of Testosterone in the body is a secret no longer. Men will have to get used to the fact that their testicles are not perfect producers of Testosterone, any more than women have perfectly producing ovaries. They must be brave enough to accept, there is no shame attached to the failure to produce Testosterone.

Doctors have been asked by the AACE to make themselves aware of this problem in their practices. However, it is the patient's responsibility, to talk about their problems and seek help.
Increased education of doctors and the general public is needed, in order to provide preventative care and catch up with many millions of existing sufferers in the world.