Diurnal rhythms of luteinizing hormone, follicle-stimulating hormone, testosterone, and estradiol secretion before the onset of female puberty in short children

To investigate hormonal changes before the onset of female puberty, we meas ured LH and FSH in serum samples drawn every 20 min for 24 h and measured t estosterone and estradiol hourly for 24 h. Seventeen girls (13 prepubertal and 4 early pubertal) of short stature, from 5.1-11.4 yr of age, participat ed in this study. LH and FSH were measured using a time-resolved immunofluo rometric assay, and testosterone and estradiol were measured using a sensit ivity RIA capable of detecting testosterone and estradiol concentrations of 10 and 2 pg/mL, respectively. Diurnal rhythms of LH, FSH, and testosterone were apparent in all subjects, including those aged 5-6 yr. Serum LH and FSH concentrations showed night- day variation in a pulsatile fashion. The serum testosterone concentration was elevated in the early morning in all subjects. The serum estradiol conc entration was elevated in the early morning in 4 of 13 prepubertal subjects and all 4 early pubertal subjects. The diurnal pattern of the serum estrad iol concentration was similar to that of the serum testosterone concentrati on. Mean 24-h LH and testosterone concentrations in prepubertal subjects wh o did not attain puberty for at least 1 yr were 0.07 U/L and 65 pg/mL, resp ectively, whereas those in prepubertal subjects who attained puberty within 1 yr (0.14 U/L, and 106 pg/mL, respectively) were significantly higher. Fu rthermore, mean 24-h LII, FSH, testosterone, and estradiol concentrations i ncreased with the onset of puberty. In conclusion, the diurnal rhythms of LH, FSH, and testosterone already exi st at 5-6 yr of age, and serum LPI and testosterone levels increase before the onset of puberty. These results suggest that preparation for the onset of female puberty may begin in 5- to 6-yr-old girls.