Over the past few weeks, I have been contacted by several friends who have each asked me if their child has started puberty too early (defined as precocious puberty). The stories have been virtually identical; healthy seven-year-olds (both boys and girls) who have recently developed underarm odor. So, what does it mean and what should be done about it (if anything)?
What is Precocious Puberty?
I would define precocious puberty as ANY pubertal changes that develop before age 8 years in girls, and before age 9 years in boys. What pubertal changes am I talking about? They would include the following: breast development in girls or boys, pubic and/or axillary hair or axillary odor in girls or boys, enlargement of the penis and/or testes in boys or acne in boys or girls. These changes might or might not be associated with a linear growth spurt.
It is important to understand that there are two separate components to puberty in both males and females: adrenarche, which is activation of androgen synthesis in the adrenal cortex glands, and gonadarche, which is activation of estrogen synthesis in the ovaries, and testosterone in the testes (the term “arche” is from the Greek and means origin or start). No one knows what actually triggers either component of puberty. In females, adrenal androgens (primarily weak androgens, such as DHA/DHEA, and DHEA-S) are responsible for most pubic and axillary hair, and axillary sweat gland development- the ovaries do make androgens, and in some cases, such as polycystic ovary syndrome and adrenal tumors, the adrenal cortex glands can crank out lots of weak androgens as well as testosterone, a strong androgen. In males, testicular testosterone synthesis is normally a far greater source of androgens than the adrenal glands. The term “pubarche,” which used to mean onset of pubic hair, has come to mean presence of androgen effects, regardless of origin.
Based on marvelous studies carried out in the 1960s in England by Marshall and Tanner (Tanner as in James Tanner, who developed the widely used sexual maturation scale, called “Tanner staging”), the dogma was that the average girl had gonadarche (breast bud development) at about age 11 years, followed within months by adrenarche. The first menstrual period, called menarche, was about 2 years after onset of breast development (on average, at about age 13 years). Boys were found to have gonadarche (testicular enlargement) at about age 11.5 years, and adrenarche about a year later. Early on, the testicular enlargement was mostly from seminiferous tubule development, with Leydig cell (the source of testicular testosterone) development quite a bit later. This is the reason boys were found to have peak pubertal linear growth quite a bit later than girls (about age 14 in males and age 11.5 years in females). Anyway, we now know that those data are not correct, at least for the U.S. population, where black and Hispanic boys and girls have considerably earlier average onset of puberty (e.g., gonadarche at 9-9.5 years in both males and females). This is also true for overweight children, regardless of their ethnic/racial background. There are also recent data suggesting that actual onset of gonadarche and adrenarche in white children are quite a bit earlier than what Marshall and Tanner found in England in the 1960s (several years ago, I wrote an entry that discussed the question of earlier onset of normal puberty- check it out if you are interested).
Based on the most recent data, some experts have suggested that we in the U.S. should redefine precocious puberty as as pubertal onset before age 6 in girls and age 7 in boys. In my opinion, we should stick with the “old” definition, but temper work-ups based on the various factors mentioned above.
Back to the Problem at Hand
So, now let’s think about how to approach a 7 year-old-girl whose parents have brought her to see you with concerns about her recent development of body odor. In my next entry, I will summarize what I told each of my friends what I would do to investigate their child’s problem, if I were their child’s doc.
- Vitamin D Deficiency: Is It Really As Common as People Say?
- Does My Patient Have Precocious Puberty? Part Two