Precocious puberty in boys is defined as the onset of puberty before the age of 9 years.
The first sign of puberty in boys is enlargement of the testes, with 4ml volume or higher being in keeping with puberty commencing. It may be a further 12-24 months before testicular volumes reach around 10mls and therefore are enlarged sufficiently to result in enough testosterone to cause a pubertal growth spurt or secondary sexual characteristics. It is often these later signs which may prompt families to present to healthcare professionals.
Initial assessment should include:
- height and weight, plotted on growth chart, ideally plotting of both parents’ height.
- clinical examination for signs of pubertal development including an estimation of testicular volumes.
- Clinical examination for secondary sexual characteristics, such as axillary and pubic hair, and penis enlargement.
- family history of pubertal timing where available.
- Consideration of red flag symptoms, such as those of a space occupying lesion. Consideration of dysmorphic features or birthmarks.
Signs of androgen exposure, such as pubic hair growth, greasy skin or body odour, in the absence of testicular enlargement, is more likely to represent adrenarche.
Who to refer:
- Boys with testicular volumes >4mls before the age of 9 years.
- Boys with growth acceleration (although bear in mind that growth acceleration is unlikely to occur until testicular volumes are >10mls).
- If considering blood tests prior to referral then please include LH/FSH/testosterone and TFTs.
Who not to refer:
- Boys with pubertal onset after the age of 9 years with no other concerning features.
- Boys with adrenarche and no red flags.
How to refer:
Please refer via SCI Gateway to RHCYP – Endocrinology
The Scottish paediatric endocrine group website contains useful SPEG parent information leaflets, including on GNRH testing and precocious puberty.
RCPCH Growth Charts
