Episodic Fluctuations of Serum Gonadotropins in Pre- and Post-Pubertal Girls and Boys

Abstract

The concentrations of LH and FSH were determined in serum samples obtained at 15 minintervals during a 4 h period from seven normal girls, 9.5–16.5 years of age, and eight normal boys, 9.0–16.8 years of age. An episodic pattern of LH secretion was found in all subjects. There wasno significant (P>0.1) difference between girls and boys as to number of episodes (3.0 ± 0.6 us. 3.0 ± 0.0 per 4 h), absolute LH increase (2.6 ± 1.1 vs. 2.4 ± 1.0 mlU per ml) or “apparent LH half-life” (64.3 ± 20.8 us. 76.1 ± 23.4min). Mean absolute increase during secretory episodes correlated (R = 0.89, P <0.005) with the mean LH concentration per 4 h, and a significant (P < 0.025) inverse correlation (R = –0.52) was found between the mean per cent incremen of the LHsecretory episode and themean “apparent LH halflife.” Minor fluctuations of FSH were alsoobserved. In girls and boys, the mean concentration of both gonadotropins increased with advancing puberty. The increase in LH concentration was due to anincrease in the amplitude of secretory episodes rather than to an increase in the number of episodes. The increase in FSH concentration reflected aconsistent elevation throughout the period of sampling.