Adrenarche is the term for the maturational increase in adrenal androgen production that becomes biochemically apparent as a rise in dehydroepiandrosterone sulfate (DHEA-S) at about six years of age in both girls and boys (figure 1). It represents a gradual change in the pattern of adrenal secretory response to corticotropin (adrenocorticotropic hormone, ACTH), characterized by a disproportionate rise of 17-hydroxypregnenolone and dehydroepiandrosterone (DHEA) relative to cortisol. This change primarily occurs in the zona reticularis of the adrenal cortex, the cells of which express a unique pattern of steroidogenic enzymes that includes expression of sulfotransferase 2A1 (SULT2A1), which catalyzes the formation of DHEA-S, the major adrenarchal steroid (figure 2). (See "Normal adrenarche".)
The causes, diagnosis, and management of premature adrenarche will be reviewed here. It is useful, however, to begin with a review of definitions used to describe the various aspects of premature sexual development as they relate to adrenarche.
The definitions used to describe normal and premature puberty and pubarche are as follows:
Puberty — Puberty is the stage of development during which secondary sexual characteristics appear and there is a transition from the sexually immature to the sexually mature stage. True puberty results from activation of the hypothalamic-pituitary-gonadal (HPG) axis. Testicular enlargement is the usual first sign of gonadal activation (gonadarche) in boys, and breast development (thelarche) is the first sign in girls, with sexual hair development ordinarily occurring later. The physiology and clinical stages of puberty are discussed in a separate topic review. (See "Normal puberty".)
Premature puberty — The exact age at which puberty is abnormally early (precocious) is not well defined. In general, signs of secondary sexual development occurring before the age of eight years in girls and the age of nine years in boys are considered premature and warrant careful evaluation. This practice is supported by data in girls, though breast budding is normal during the seventh year in Black and Mexican-American girls , while good data are still lacking in boys . Gonadotropin-dependent precocious puberty (also termed “central,” “true,” “or “complete” precocity) results from activation of the normal HPG axis. Gonadotropin-independent precocious puberty (also termed “peripheral” precocious puberty) results from excess exposure to androgens or estrogens derived from the gonads, adrenal glands, exogenous sources, or ectopic production of human chorionic gonadotropin (hCG) by a tumor. (See "Definition, etiology, and evaluation of precocious puberty".)