Which test is used to confirm Turner syndrome?

• A. Karyotyping
• B. Serum FSH
• C. Ultrasound
• D. MRI

Answer: (A)

Turner syndrome is a chromosomal condition caused by loss or alteration of one X chromosome, so the definitive way to confirm it is to analyze the patient’s chromosomes. Karyotyping looks at the number and structure of all chromosomes in a sample of cells (usually blood) and can reveal a 45,X pattern or a mosaic pattern such as 45,X/46,XX, which confirms Turner syndrome.

Other tests may raise suspicion or show related features but do not provide a definitive diagnosis. Serum FSH can be elevated because of gonadal dysgenesis, but it isn’t specific to Turner. Ultrasound might reveal ovarian streaks or certain congenital anomalies, but it doesn’t prove the diagnosis. MRI isn’t used to confirm Turner syndrome.