A 7-year-old girl presents with breast development (Tanner stage 2) and pubic hair, with advanced bone age (10 years). GnRH stimulation test shows LH >5 IU/L (pubertal response). Brain MRI is normal. She is diagnosed with idiopathic central precocious puberty. The MOST appropriate pharmacological treatment and its mechanism are:

• A GnRH antagonist (cetrorelix) given pulsatile, mimicking physiological GnRH secretion
• B GnRH agonist (leuprolide/triptorelin) given continuously, which desensitises pituitary GnRH receptors and suppresses gonadotrophin release ✓
• C Medroxyprogesterone acetate, which suppresses adrenal androgen production
• D Letrozole (aromatase inhibitor), which blocks oestrogen synthesis and halts breast development

Explanation

GnRH agonists (leuprolide, triptorelin, histrelin) are the gold standard for central precocious puberty. When given continuously (rather than in physiological pulses), they cause downregulation and desensitisation of pituitary GnRH receptors, leading to sustained suppression of FSH, LH, and downstream sex steroid production. This halts pubertal progression and allows bone age to close more slowly, preserving final adult height. GnRH antagonists given pulsatile would stimulate gonadotrophins. Medroxyprogesterone was an older treatment. Aromatase inhibitors are used in peripheral precocity (McCune-Albright) or as an adjunct.

Reference: Ghai Essential Pediatrics, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.