Effects of pure human follicle-stimulating hormone (pFSH) on sperm quality correlate with the hypophyseal response to gonadotrophin-releasing hormone (GnRH)*

In 41 men with idiopathic infertility, the effect of pure follicle-stimulating hormone (pFSH) therapy on semen parameters was evaluated in relation to the results of the gonadotrophin-releasing hormone (GnRH) stimulation test in an open study. The patients showed a mean (+/-standard error) sperm concentration of 15.84 (+/-2.87) Mill. ml-1, 41.02 (+/-4.19)% of the spermatozoa were motile and 46.16 (+/-2.36)% normomorph before treatment. All patients were administered 150 IU pFSH subcutaneously three times weekly for 10 weeks. After therapy with pFSH, no significant differences compared with the pre-treatment sperm characteristics were observed (P > 0.05) except for the velocity average path, VAP (P = 0.029). However, the stimulation factors of FSH in the GnRH test showed a significantly negative correlation with the pFSH mediated improvement of sperm concentration (r = -0.662, P = 0.000002), of percentage of normomorph spermatozoa (r = -0.480, P = 0.0015) and total count of motile spermatozoa per ejaculate (r = -0.567, P = 0.00014). In consequence, the patients were divided into two groups depending on the stimulation factor of hypophyseal FSH secretion, FSH-SF. The cut-off point of the FSH-SF was set at 1.7 because the correlation analyses detected a 1.5-fold improvement of sperm parameters at this hypophyseal response on average. Pure FSH treatment increased the concentration of spermatozoa (P = 0.0007), the total count of motile spermatozoa in the ejaculate (P = 0.015) as well as the computer-aided sperm motion parameters VAP (P = 0.029) and velocity curve linear, VCL (P = 0.049) in patients with FSH-SF < 1.7, whereas in the patient group with FSH-SF > 1.7 no improvement of semen parameters was found. Insufficient stimulation of hypophyseal FSH secretion may be a prerequisite but not a guarantee for responsiveness to pFSH treatment. The results of the present investigation suggest that FSH stimulation in the GnRH test should be taken into account in idiopathic infertile men before pFSH therapy.