In females, normal puberty begins between 8 - 12 years of age with the onset of breast development, or thelarche, followed by pubic hair growth, or pubarche.
Menarche occurs between 2 - 3 years after thelarche. Primary amenorrhea is defined as the absence of menarche by 15 years of age in the presence of normal growth. Secondary amenorrhea is defined as the absence of menses for at least 6 months after onset of normal menarche.
In order to occur, menarche requires:
(a) the presence of a uterus
(b) a patent outflow tract
(c) proper functioning of the hypothalamic-pituitary-ovarian axis
- ie, GnRH pulsatility, LH/FSH release, and appropriate ovarian
response to circulating LH/FSH
When approaching primary amenorrhea, it may be helpful to think in terms of the origins of primary and secondary sexual characteristics.
An algorithm for working through differential diagnoses using this information is presented below.
The pathway of male sexual differentiation is important to keep in mind when thinking through conditions where there is an inconsistency between the sex chromosomes and the sexual phenotype present.
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