Luteinizing hormone secretion patterns in boys at the onset of puberty measured using a highly sensitive immunoradiometric assay.

Abstract

Pulsatile LH secretion was studied in 3 prepubertal and 11 early pubertal boys by measuring plasma LH concentrations at 10-min intervals from 1200-1800 h and from 2400-0600 h using an immunoradiometric assay with a lower limit of detection of 0.10 IU/L. Plasma testosterone (T) was measured hourly. In the prepubertal boys plasma LH was not detectable during the daytime but at night 20- to 300-min periods of detectable, but low (less than 0.5 IU/L) plasma LH values occurred. A discrete episodic LH pattern was discernible, and the median number of pulses was 2 during the 6-h nocturnal sampling periods. Plasma T was not detectable (less than 1.0 nmol/L). In the pubertal boys most daytime plasma LH values were greater than 0.3 IU/L, with periods of values of 0.1-0.3 IU/L and short periods of undetectable levels as well. At night definite pulses, up to 4.7 IU/L, were found in all boys. The median number of pulses was 4 during the 6-h nocturnal sampling period. Plasma T was detectable at night in 5 of these 11 boys. The results strongly suggest that at the onset of puberty prepubertal boys (G1) have no LH secretion during the day but intermittent gonadotrophic activity during the night. In early puberty LH secretion increases in amplitude as well as frequency to a clear pulsatile pattern during the night, sometimes with pulses during the day as well.