Which pattern distinguishes central from peripheral precocious puberty?

• A. Central: suppressed LH and FSH with elevated sex steroids; Peripheral: elevated LH and FSH in response to GnRH
• B. Central: elevated LH and FSH in response to GnRH; Peripheral: suppressed gonadotropins with elevated sex steroids
• C. Central: no response to GnRH; Peripheral: increased sex steroids with no change in gonadotropins
• D. Central: high prolactin after GnRH; Peripheral: low prolactin

Answer: (B)

The key idea is whether puberty is driven by the hypothalamic-pituitary-gonadal axis or by outside sources of sex steroids. In central precocious puberty, the axis is activated early, so the pituitary readily responds to GnRH with an increase in LH and FSH, driving higher sex steroid levels. A GnRH stimulation test in this scenario shows a rise in both LH and FSH, reflecting gonadotropin dependence.

In peripheral precocious puberty, sex steroids come from the ovaries, adrenals, or exogenous sources, independent of the pituitary. The high sex steroids suppress pituitary gonadotropin production via negative feedback, so basal LH and FSH are low and show little or no increase with GnRH stimulation, even though sex steroids are elevated.

So the best description is that central precocious puberty has an elevated LH/FSH response to GnRH, while peripheral precocious puberty has suppressed gonadotropins with elevated sex steroids.