Dynamic GnRH- and hCG-Testing

Michael Scally MD

Doctor of Medicine
10+ Year Member
Bang AK, Nordkap L, Almstrup K, et al. Dynamic GnRH- and hCG-testing: establishment of new diagnostic reference levels. European Journal of Endocrinology. http://www.eje-online.org/content/early/2017/01/11/EJE-16-0912.abstract (Dynamic GnRH- and hCG-testing: establishment of new diagnostic reference levels.)?

Objective. Gonadotropin-releasing hormone (GnRH) and Human Chorionic Gonadotropin (hCG) stimulation-tests may be used to evaluate the pituitary and testicular capacity. Our aim was to evaluate changes in follicular-stimulating hormone (FSH), luteinizing hormone (LH) and Testosterone after GnRH and hCG stimulation in healthy men, and assess the impact of six single nucleotide polymorphisms on the responses.

Design. GnRH- and hCG-stimulation tests were performed on 77 healthy men, 18-40 years (reference group) at a specialized andrology referral center. The potential use of the tests was illustrated by results from 45 patients suspected of disordered hypothalamic-pituitary-gonadal axis.

Methods. Baseline, stimulated, relative and absolute changes in serum FSH and LH were determined by ultrasensitive TRIFMA, and testosterone was determined by LC-MS/MS.

Results. For the reference group LH and FSH increased almost 400% and 40% during GnRH testing, stimulated levels varied from 4.4-58.8 U/L and 0.2-11.8 U/L, FSH decreased in nine men. Testosterone increased approximately 110% (range 18.7-67.6 nmol/l) during hCG-testing. None of the polymorphisms had any major impact on the test results.

Results from GnRH and hCG-tests in patients compared to the reference group showed that the stimulated level and absolute increase in LH showed superior identification of patients compared to the relative increase, and the absolute change in Testosterone was superior in identifying men with Leydig cell insufficiency, compared to the relative increase.

Conclusions. We provide novel reference ranges for GnRH and hCG test in healthy men, which allows future diagnostic evaluation of hypothalamic-pituitary-gonadal disorders in men.
 
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