Early puberty in boys

The Pediatric Insider

© 2010 Roy Benaroch, MD

Allison posted, “I’ve got a friend whose (just turned) 8 year old son is showing signs of puberty ‘down there.’ I told her that was VERY early and that I’d get it checked out. Thoughts?”

Although it’s actually considered normal for girls to begin puberty at age 8, true pubertal changes in an eight year old boy are abnormal and ought to be evaluated.

But first: is he really experiencing puberty? The first sign of true puberty in a boy is enlarging testicles, followed by growth of the penis. These changes are driven by hormones produced in the pituitary glands and testicles. Although pubic hair, body odor, and acne often appear at about the same time, these changes are related to hormones from the adrenal glands, and are not really part of true puberty. A boy with only the appearance of hair, without testicle and penis growth, may not be entering puberty. He can be watched for signs of further development without further immediate workup. But a boy who’s truly entering puberty at age 8 needs a thorough evaluation.

Evaluating early puberty starts with careful measurement of height– puberty will coincide with an increased growth rate, so if a boy is suddenly becoming taller, that’s a definite sign of puberty. A careful physical exam by an experienced physician is essential. Sometimes, a bone age x-ray is useful, or blood tests of hormone status are needed. Some of these boys will also need an MRI scan of their pituitary glands, or other radiology exams.

Though early puberty in a girl is rarely caused by a serious underlying health condition, at least half of boys with true early puberty are going to have an underlying cause that needs to be found and addressed. Boys with true early puberty are much more concerning than girls. Allison ought to tell her friend to get her son to the pediatrician for an exam and further workup.

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One Comment on “Early puberty in boys”

  1. Allison Says:

    Thanks! I will. So far, all she noticed was hair, but I’m sure she didn’t take notice of the other factors you’ve pointed out. I’m sure she will now…..


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