Which finding would most strongly support a diagnosis of precocious puberty in an 8-year-old boy?

Which finding would most strongly support a diagnosis of precocious puberty in an 8-year-old boy?

• A. Testicular length 2.1 cm
• B. Café-au-lait spots
• C. Growth spurt of 5 cm/year
• D. Normal blood glucose level (97 mg/dL)

Answer: (B)

The key idea is distinguishing a peripheral, gonadotropin-independent cause of precocious puberty from a typical central onset. Café-au-lait spots point to McCune-Albright syndrome, which can cause early puberty because tissues outside the pituitary (like gonads) produce sex steroids autonomously. In this scenario, the spots are a specific clue that puberty is driven by an abnormal tissue source rather than early activation of the HPG axis—making this finding the strongest support for precocious puberty due to a pathological syndrome. A testicular length of 2.1 cm suggests prepubertal testes rather than gonadotropin-driven testicular enlargement seen in central puberty. A growth spurt of 5 cm/year can occur with puberty but is not specific. A normal glucose level doesn’t inform puberty status.

The key idea is distinguishing a peripheral, gonadotropin-independent cause of precocious puberty from a typical central onset. Café-au-lait spots point to McCune-Albright syndrome, which can cause early puberty because tissues outside the pituitary (like gonads) produce sex steroids autonomously. In this scenario, the spots are a specific clue that puberty is driven by an abnormal tissue source rather than early activation of the HPG axis—making this finding the strongest support for precocious puberty due to a pathological syndrome.

A testicular length of 2.1 cm suggests prepubertal testes rather than gonadotropin-driven testicular enlargement seen in central puberty. A growth spurt of 5 cm/year can occur with puberty but is not specific. A normal glucose level doesn’t inform puberty status.