Pathogenesis and epidemiology of precocious puberty. Effects of exogenous oestrogens

Precocious puberty is generally defined as the appearance of secondary sex characteristics before age 8 years in girls (or menarche before age 9 years ) and before 9 years in boys. The overall incidence of sexual precocity is estimated to be 1:5000 to 1:10 000 children. The female-to-male ratio is si milar to 10:1, In addition to the psychosocial disturbances associated with precocious puberty, the premature pubertal growth spurt (with less time fo r prepubertal growth) and the:accelerated bone maturation result in reduced adult height. Precocious puberty may be gonadotrophin-dependent [i.e. of c entral origin with premature activation of the gonadotrophin-releasing horm one (GnRH) pulse generator] or gonadotrophin-independent (i.e, peripheral w here the GnRH pulse generator is suppressed). This can be determined by GnR H testing. The pathophysiology is the basis for different diagnostic and th erapeutic strategies, i.e. in the first case a stimulated LH/FSH ratio >1 a nd suppressive treatment with GnRH agonists (e,g, in hypothalamic hamartoma ), and in the second decreased gonadotrophins and removal or suppression of the endogenous or exogenous sex steroid source (e,g, congenital adrenal hy perplasia), While several cases of gonadotrophin-independent precocious pub erty due to oestrogen exposure via the transdermal, oral, or inhalative rou te have been reported, no case is known with the development of subsequent secondary central precocious puberty. Food contamination with oestrogens is theoretically possible, but would most probably be sporadic and, thus,woul d not lead to precocious puberty. As steroid hormones in meat production ar e banned in the European Union, no data on the impact of environmental oest rogenic substances on human maturation are currently available. In conclusi on,:the risk for children to develop precocious puberty through exposure to oestrogens (or androgens) in the environment or in food is very low. Never theless, studies of the effects of defined environmental oestrogenic substa nces on the human reproductive system and on pubertal development are warra nted.