Physiology of the Hypothalamic Pituitary Gonadal Axis in the Male.

Testosterone synthesis and male fertility are the results of the perfect coordination of the hypothalamic-pituitary-gonadal axis. A negative feedback finely controls the secretion of hormones at the 3 levels. Congenital or acquired disturbance at any level leads to an impairment of reproductive function and the clinical syndrome of hypogonadism. In some cases, this condition is reversible. Once the diagnosis is made, testosterone replacement therapy is the standard therapy; however, novel therapies may improve spermatogenesis while elevating testosterone levels.