Developmental Changes in Neuroendocrine Regulation of Gonadotropin Secretion in Gonadal Dysgenesis

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Abstract
Patients with gonadal dysgenesis have a marked increase in gonadotropin levels at the age when puberty normally occurs. To determine whether this increase results from a change in the frequency or the amplitude of gonadotropin pulses, we measured the 24-h profile of plasma LH and FSH by RIA in 31 patients with gonadal dysgenesis, aged 2–20 yr. Gonadotropin pulses were defined as a rise from nadir to peak that exceeded 3 times the intraassay coefficient of variation. This criterion, based on an empirical study of RIA noise, reduced the rate of false positive peaks to less than 3–4/24 h. Using this criterion, peak amplitude increased significantly at the time of puberty for both LH and FSH (P < 0.01). The overall frequency of gonadotropin pulses (the sum of the FSH peaks plus the LH peaks that occurred without a concomitant FSH peak), however, did not differ among prepubertal (12.7 ± 1.8 peaks/24 h), pubertal aged (14.3 ± 2.3 peaks/24 h), and adult patients (14.7 ± 0.9 peaks/24 h). Thus, the increase in gonadotropin concentration in pubertal aged patients with gonadal dysgenesis appears to result primarily from an increase in gonadotropin peak amplitude rather than an increase in peak frequency.