Male hypogonadism is a clinical syndrome that occurs due to disruption of the hypothalamic–pituitary–testicular (HPT) axis, and results in failure to produce physiological levels of testosterone and normal numbers of spermatozoa. It includes androgen deficiency and infertility, which may be present together or separately. Hypogonadism can be further divided into subtypes on the basis of the location of the dysfunction of the HPT axis:
- Primary if the dysfunction is located at the level of the testes
- Secondary if the dysfunction is located at the level of the hypothalamus or pituitary gland