Dynamic GnRH and hCG testing: establishment of new diagnostic reference levels

Area of Science:

• Endocrinology
• Reproductive Medicine
• Andrology

Background:

• The hypothalamic-pituitary-gonadal (HPG) axis is crucial for reproductive health in men.
• Gonadotropin-releasing hormone (GnRH) and human chorionic gonadotropin (hCG) stimulation tests are utilized to assess pituitary and testicular function.
• Understanding normal hormonal responses is essential for diagnosing HPG axis disorders.

Purpose of the Study:

• To evaluate the changes in follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone following GnRH and hCG stimulation in healthy men.
• To establish novel reference ranges for these hormonal responses.
• To assess the impact of single nucleotide polymorphisms on these test outcomes.

Main Methods:

• Seventy-seven healthy men (18-40 years) underwent GnRH and hCG stimulation tests.
• Serum FSH and LH levels were measured using ultrasensitive TRIFMA.
• Testosterone levels were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Main Results:

• GnRH stimulation led to significant increases in LH (approx. 400%) and FSH (approx. 40%) in healthy men.
• hCG stimulation resulted in an approximate 110% increase in testosterone levels.
• Absolute changes in LH and testosterone were more effective in identifying patients with HPG axis dysfunction compared to relative changes.

Conclusions:

• Novel reference ranges for GnRH and hCG stimulation tests in healthy men have been established.
• These reference ranges are valuable for the diagnostic evaluation of male HPG axis disorders.
• The study found no major impact of the investigated polymorphisms on the test results.