Testicular activity in Cushing's disease

Area of Science:

• Endocrinology
• Reproductive Medicine
• Metabolic Disorders

Background:

• Cushing's disease is characterized by excess cortisol production.
• Sexual dysfunction, including loss of libido and decreased potency, is a common complaint in affected males.
• The relationship between Cushing's disease, testosterone levels, and the hypothalamic-pituitary-gonadal axis requires further elucidation.

Purpose of the Study:

• To investigate plasma testosterone and gonadotropin levels in male patients with Cushing's disease.
• To explore the potential causes of suppressed testosterone in this patient population.
• To assess the impact of cortisol excess correction on testosterone levels.

Main Methods:

• Assessed plasma testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), and estradiol levels in 8 male patients with Cushing's disease.
• Measured gonadotropin response to gonadotropin-releasing hormone (GnRH) stimulation.
• Evaluated testicular response to human chorionic gonadotropin (hCG) stimulation in two patients.
• Monitored hormone levels before and after surgical correction of cortisol excess.

Main Results:

• Six out of eight male patients exhibited suppressed plasma testosterone levels.
• Basal and GnRH-stimulated gonadotropin levels were generally normal.
• Testicular response to hCG was normal in the two patients tested.
• Testosterone levels normalized following successful treatment for Cushing's disease.

Conclusions:

• Male patients with Cushing's disease frequently present with low testosterone and normal gonadotropin levels, suggesting a complex interplay of factors.
• Potential mechanisms include impaired hypothalamic and testicular function or a downward resetting of the hypothalamic-pituitary-gonadal axis set-point.
• Correction of hypercortisolism effectively restores normal testosterone levels, highlighting the crucial role of cortisol in male reproductive health.