Baseline follicle-stimulating hormone is a strong predictor for the outcome of the gonadotrophin-releasing hormone test in young men with unilateral medium- or high-grade varicocele.

Objective: To investigate whether the gonadotrophin-releasing hormone (GnRH) test is an adequate diagnostic tool to identify testicular dysfunction in men with strictly unilateral varicocele and defined testicular volume; and to identify any peripheral venous variable which would predict the result of the GnRH test.
Patients and Methods: In all, 102 GnRH tests were done in men with a left-sided varicocele. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels were determined. After intravenous administration of 100 microg GnRH, stimulated LH and FSH levels were measured. FSH levels of >8.2 U/L and LH levels of >51.7 U/L were considered exaggerated.
Results: In all, 50 men had an exaggerated GnRH test result; all had an exaggerated FSH response and six also had an elevated LH response. The baseline FSH levels were higher (P < 0.001) and the testicular volume was smaller (P < 0.01) in men with an exaggerated GnRH test response. All men with a baseline FSH level of >5.6 U/L had an exaggerated GnRH test response.
Conclusion: A baseline FSH level of >5.6 U/L is a good predictor of the GnRH test outcome. Leydig cell function seems mainly undisturbed.