CHANGES IN GONADOTROPIN-SECRETION DURING CHILDHOOD AND PUBERTY

The changes in gonadotrophin secretion in childhood and puberty involv e changes in the pulsatile pattern as well as mean concentration. We h ave examined pulsatile secretion using 24-h LH profiles in 78 children aged 4.2-15.6 years and six adult men. The profiles were analysed by a method which gives an estimate of peak and baseline levels and by sp ectral analysis. Prepubertal children were divided into groups by age and pubertal children by pubertal stage. Baseline LH levels in childre n aged 4.2-6.9 years were higher than in those aged 7.1-9.8 years. Pul se frequency in both groups was slow (periodicities 140-200 min). In t he oldest prepubertal group there was an increase in peak levels with increased spectral power at periodicities of 100-120 min. Pulse freque ncy did not change in puberty (periodicity 120-160 min). Girls demonst rated an increase in both peak and baseline LH concentrations in early puberty. Boys had an increase in only peak levels in early puberty; t here was no increase in baseline concentrations until a testicular vol ume of 10 ml was attained. In conclusion, these data show that LH leve ls do not reach a nadir until 8 years of age. We have detected a sex d ifference in the pattern of LH secretion seen in early puberty, and th is mirrors clinical findings. The mature pattern attained by the end o f puberty in both sexes is probably important for fertility.