Which finding on genital examination marks the onset of puberty in a boy?
- A Testicular volume of 4 mL or more ✓
- B Appearance of pubic hair
- C Penile lengthening
- D Voice deepening
Correct answer: A. Testicular volume of 4 mL or more
Explanation
Puberty in boys begins with enlargement of the testes to a volume of 4 mL or more (longest diameter greater than 2.5 cm), corresponding to Tanner genital stage 2, driven by rising gonadotropins. Pubic hair reflects adrenal androgen production and can appear independently, so it does not define gonadal puberty. Penile growth and voice change occur later, in Tanner stages 3 and 4 respectively.
Reference: Nelson Textbook of Pediatrics, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.