Physiology of the Hypothalamic Pituitary Gonadal Axis in the Male

[Michael Scally MD]

Corradi PF, Corradi RB, Greene LW. Physiology of the Hypothalamic Pituitary Gonadal Axis in the Male. Urologic Clinics of North America 2016;43(2):151-62. https://www.sciencedirect.com/science/article/pii/S0094014316000021

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.

 

[Michael Scally MD]

Herati AS, Cengiz C, Lamb DJ. Assays of Serum Testosterone. Urologic Clinics of North America 2016;43(2):177-84. https://www.sciencedirect.com/science/article/pii/S0094014316000045

The diagnosis of male hypogonadism depends on an assessment of the clinical signs and symptoms of hypogonadism and serum testosterone level.

Current clinical laboratory testosterone assay platforms include immunoassays and mass spectrometry.

Despite significant advances to improve the accuracy and precision of the currently available assays, limited comparability exists between assays at the lower and upper extremes of the testosterone range.

Because of this lack of comparability, there is no current gold standard assay for the assessment of total testosterone levels.

 

[Dr JIM]

Herati AS, Cengiz C, Lamb DJ. Assays of Serum Testosterone. Urologic Clinics of North America 2016;43(2):177-84. https://www.sciencedirect.com/science/article/pii/S0094014316000045


..... limited comparability exists between assays at the lower and upper extremes of the testosterone range.

and is one reason why TT levels are most useful when correlated with clinical findings, as doing so provides a more accurate assessment of male hypogonadism.