Paediatric and adult-onset male hypogonadism

TLDR: This Primer focuses on a reappraisal of the physiological role of testosterone, with emphasis on the critical interpretation of the hypog onadal conditions throughout the lifespan of the male individual, with the exception of hypogonadal states resulting from congenital disorders of sex development.

Abstract: The hypothalamic–pituitary–gonadal axis is of relevance in many processes related to the development, maturation and ageing of the male. Through this axis, a cascade of coordinated activities is carried out leading to sustained testicular endocrine function, with gonadal testosterone production, as well as exocrine function, with spermatogenesis. Conditions impairing the hypothalamic–pituitary–gonadal axis during paediatric or pubertal life may result in delayed puberty. Late-onset hypogonadism is a clinical condition in the ageing male combining low concentrations of circulating testosterone and specific symptoms associated with impaired hormone production. Testosterone therapy for congenital forms of hypogonadism must be lifelong, whereas testosterone treatment of late-onset hypogonadism remains a matter of debate because of unclear indications for replacement, uncertain efficacy and potential risks. This Primer focuses on a reappraisal of the physiological role of testosterone, with emphasis on the critical interpretation of the hypogonadal conditions throughout the lifespan of the male individual, with the exception of hypogonadal states resulting from congenital disorders of sex development. Male hypogonadism is a disorder associated with low testosterone levels and impaired spermatogenesis. The condition can arise from inherent defects in the testes or abnormalities in the regulation of testosterone secretion at the hypothalamic or pituitary level. This Primer summarizes the conditions that can lead to hypogonadism in boys and men.