An 8-year-old girl begins developing breast buds and pubic hair. Her bone age is 10 years. GnRH stimulation test shows a pubertal LH response. The most appropriate next investigation to identify the cause is:

• A Karyotype analysis
• B Adrenal CT scan
• C MRI of the brain and hypothalamic-pituitary region ✓
• D Pelvic ultrasound for ovarian volume

Explanation

This child has central (gonadotropin-dependent) precocious puberty (CPP) — the GnRH stimulation test showing pubertal LH confirms gonadotropin dependency. In girls with CPP, the majority are idiopathic, but CNS lesions (hypothalamic hamartoma, astrocytoma, hydrocephalus) must be excluded, especially with bone age advancement. MRI brain with focus on the hypothalamic-pituitary region is mandated. Karyotype is relevant for Turner or ambiguous genitalia. Adrenal CT is for adrenal causes (peripheral/gonadotropin-independent). Pelvic ultrasound helps confirm ovarian enlargement but doesn't identify the etiology.

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.