ESPE Abstracts

Objectives: We designed a longitudinal study to investigate the association between central pubertal activation with age at the appearance of clinical signs of puberty. We, therefore, assessed nocturnal gonadotropin secretion which can be detected in the form of total luteinizing hormone (LH) immunoreactivity in the daytime- and sleeptime-excreted urine.

Methods: Thirty healthy volunteers (17 boys and 13 girls, aged 3.4–15.2 yr and 4.3-14.3 yr respectively at the beginning of the study) were included in the study. Male and female subjects were followed for an average of 15 visits during 5.5 and 5.8 years on average, respectively. In each visit, subjects provided 24-hour urine samples divided into sleeptime and waketime portions according to the participant’s sleep-and-wake rhythm. Total urinary LH (U-LH) concentrations were measured in duplicate by Delfia® IFMA (Wallac), which has been designed specifically to detect intact LH as well as the beta-subunit and its core fragment, but not the human chorionic gonadotropin.

Results: The initial increases in sleeptime-excreted total U-LH concentrations over the cut-off value of 0.6 IU/L occurred at around the same time (around 9.75 years of age) in both sexes. The mean time span from the age at which sleeptime total U-LH concentration first exceeded the 0.6 IU/L level to observing pubertal stage 2 was 1.5 yr in boys and 0.3 yr in girls.

Conclusions: Findings in our population with a limited sample size suggest that the timing of central pubertal activation is a sex-independent phenomenon, which can be observed by monitoring the nighttime total LH concentrations in sleeptime-excreted urine samples. The lag time from central pubertal activation of gonadotropin secretion to the clinical onset of puberty is significantly longer in boys.