A 14-year-old girl presents with short stature, height at the 1st centile. She has never menstruated, has widely spaced nipples, a low posterior hairline, and cubitus valgus. Her bone age is delayed relative to chronological age. Which single investigation will best confirm the diagnosis?
- A Serum growth hormone levels after provocation
- B Karyotype analysis ✓
- C Serum TSH and free T4
- D Pelvic ultrasonography
Correct answer: B. Karyotype analysis
Explanation
The combination of short stature, primary amenorrhea, shield chest with widely spaced nipples, webbed neck, low hairline, and cubitus valgus points to Turner syndrome (45,X or mosaicism), confirmed by karyotyping. GH stimulation tests may be subnormal in Turner syndrome but do not establish the diagnosis. Pelvic ultrasound showing streak ovaries supports but does not confirm, since karyotype defines the chromosomal disorder itself.
Reference: Nelson Textbook of Pediatrics, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.