A testosterone deficiency can cause a wide range of symptoms and serious diseases. These differ depending on whether the testosterone deficiency occurs in adulthood or before puberty.

Testosterone deficiency in adult men

Illness or aging can lead to development of a testosterone deficiency in adult men.

The signs and symptoms of testosterone deficiency are as numerous as the hormone's functions. They usually develop insidiously. Moreover, not everyone with a testosterone deficiency has all the symptoms at the same time or to the same extent. Many patients therefore have difficulty describing their symptoms and complaints fully and accurately. A questionnaire has therefore been developed to make it easier for patients to identify and describe their complaints.

Testosterone deficiency before onset of puberty

If the testosterone deficiency begins before puberty, development of the male secondary sexual characteristics does not take place (no deepening of the voice, no beard growth, no male body hair and pubic hair). The testes and penis remain small and childlike. Testosterone is also responsible for termination of longitudinal growth in puberty. Absence of the action of testosterone can therefore lead to excessive tallness with extremely long legs and arms.

Insufficient production of testosterone by the unborn fetus in the womb results in inadequate or absent development of the sex organs (e.g. penis absent or too small) and a female phenotype even though the child is genetically male.