pediatrics
Precocious Puberty
Introduction
Precocious puberty is onset of sexual maturation before the average age. Diagnosis is by comparison with population standards, x-rays of the left hand and wrist to assess skeletal maturation and check for accelerated bone growth, and measurement of serum levels of gonadotropins and gonadal and adrenal steroids. Treatment depends on the cause. In girls, the first pubertal milestone is typically breast development (thelarche), followed soon after by appearance of pubic hair (pubarche) and axillary hair and later by the first menstrual period (menarche), which traditionally occurs 2 to 3 years after thelarche. Bars indicate normal ranges. In boys, the first pubertal milestone is typically testicular growth, followed by penile growth and appearance of pubic and axillary hair. Bars indicate normal ranges. No mean is available for change in habitus. In both sexes, appearance of pubic and axillary hair is called adrenarche. Adrenarche may occur before gonadarche in about 10% of children (premature adrenarche). Although gonadarche and adrenarche may have overlapping signs, they are regulated independently. The definition of precocious puberty has traditionally been before age 8 in girls or age 9 in boys. However, the current definition depends on reliable population standards for onset of puberty (ie, when pubertal milestones occur); because onset is occurring earlier in the US, especially in females, these traditional standards are being reevaluated. Breast development is increasingly occurring at younger ages. This trend is mirroring the obesity epidemic, with a higher body mass index (> 85th percentile) associated with earlier thelarche. Almost 8 to 10% of White girls, 20 to 30% of Black girls, and up to 20% of Hispanic girls reach puberty at age 8. The lower limit of normal puberty may be 7 years for White girls and 6 years for Black girls. The mean age for early breast development is about 9.5 to 10 years for White girls and 8.5 to 9 years for Black girls (range 8 to 13 years). The mean age for pubic hair growth is 9.5 years for Black girls and 10.5 years for White girls. However, the age of menarche has not lowered as drastically, with a mean decrease of only 3 months in the past 30 years (mean age 11.5 years in Black girls and 12.5 years in White girls). These findings imply that guidelines for evaluating disorders that cause precocious puberty can be interpreted more leniently if children are otherwise healthy and are projected to reach their full adult height potential. 