MSFinals-4668

MSFinals-4668

A 4-year-old girl is brought to the pediatrician by her mother. The mother is concerned as she has noticed some hair growing in her daughter’s armpits, and although she has not shown any distress or had any other noticeable symptoms, the mother is worried that something is wrong as she is too young to begin going through puberty. On examination, the child has axillary hair growth bilaterally, and her breasts are of appropriate size for her age.

Gonadotrophin assays show the following:
FSH 0.2 IU/L Age 6 months – 10 years old: (1 – 3)
LH 0.1 IU/L Age 6 months – 10 years old: (1 – 5)

What is the most likely cause of this child’s axillary hair growth?