[Dynamics of gonadotropin secretion in oligospermia with isolated elevation of follicle stimulating hormone (FSH)].

The mechanism of oligospermia with high level of follicle stimulating hormone (FSH) and normal levels of luteinizing hormone (LH) and testosterone is subject to controversy: pituitary origin with slowing down of LH pulses, or primary gonadal deficiency? We studied 23 men presenting with this hormonal profile. Compared with a control population, these men had decreased mean testosteronaemia, increased mean LH level, both at baseline and under LHRH, and increased area under the LH pulsatility curve. A positive correlation was found between LH and FSH plasma levels. These data are in favour of a primary gonadal deficiency, and we therefore expected to find an increased frequency and amplitude of LH pulses. In fact, the frequency was normal and the amplitude increased in one half of these men, while the frequency was reduced and the amplitude also increased in the other half. There was no difference in plasma FSH levels between these two groups. Pulsed administration of LHRH restored physiological stimulation, but it did not result in normalisation of the FSH/LH ratio and cannot be regarded as a suitable treatment. It would therefore seem that the mechanism of oligospermia with isolated high FSH level is an abnormal feedback of gonadal peptides and steroids.