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Puberty-Some new thoughts
Title: Rapid maturation of the reproductive axis during
perimenarche independent of body composition
Author: R. Legro, et al.
Address: Hershey, PA
Source: The Journal of Clinical Endocrinology & Metabolism 85:1021-1025
(March) 2000
Summary: Researchers sought to identify the natural history of menarche
in a large, healthy cohort of young women studied at 6-month intervals over a
4-year period beginning at premenarche. Subjects were 112 premenarchal Caucasian
females. Researchers quantified reproductive hormones in 24-hour urine
collections as a measure of daily output and measured body composition
biometrically and with the use of dual energy x-ray absorptiometry scans. Sex
steroid and gonadotropin levels changed exponentially in the year approaching
menarche. FSH levels peaked at menarche and then progressively declined
thereafter. Estradiol output increased rapidly in the year approaching menarche
and then plateaus thereafter. The frequency of menstrual bleeding increased
rapidly and plateaued at 1 year postmenarche. At 1 year, 65% had established a
pattern of 10 or more menstrual episodes/yr, and by 3 years postmenarche this
figure exceeded 90%. Researchers concluded that menarche occurs as a result of
rapid maturation of the reproductive axis, independent of changes in body fat,
and heralds the reestablishment of a negative sex steroid feedback loop that
parallels the adult threshold.