Pulsatile secretion of luteinizing hormone and sleep-related gonadotropin rhythms in girls with premature thelarche.

The concentrations of LH, FSH and PRL were determined in serum samples obtained at night in 1-2 h intervals as well as at 15 min intervals during a 3 h period between 9 and 12 p.m. and 9 and 12 a.m. in three girls with premature thelarche, who had not developed further signs of precocious puberty for more than 18 months. A sleep-dependent LH and FSH increase was documented in all of them with a predominance of FSH secretion during sleep and after LHRH stimulation. In all three girls an episodic pattern of LH was found during sleep. In daytime minor fluctuations of LH secretion were found in two patients whereas in one patient an episodic LH pattern was demonstrable with minor peak values as during sleep. Normal PRL secretion during sleep as well as after TRH stimulation excludes a permissive role of this hormone in premature thelarche. We conclude that in girls with isolated premature thelarche a matured hypothalamo-pituitary gonadotropin axis is active comparable to normal pubertal children.