In an iodine-sufficient population, what is the most common cause of permanent congenital hypothyroidism identified by newborn screening?
- A Dyshormonogenesis due to thyroid peroxidase deficiency
- B Thyroid dysgenesis, most often an ectopic gland ✓
- C Transient TSH elevation from maternal antibody transfer
- D Hypothalamic-pituitary (central) hypothyroidism
Correct answer: B. Thyroid dysgenesis, most often an ectopic gland
Explanation
Thyroid dysgenesis accounts for roughly 80 to 85 percent of permanent congenital hypothyroidism in iodine-sufficient regions, with ectopic thyroid tissue being the single most common form, followed by agenesis and hypoplasia. Dyshormonogenesis contributes only about 10 to 15 percent and is suggested by a large goitre with high uptake on scintigraphy. Central hypothyroidism is rare, around 1 in 25,000, and is missed by TSH-only screening programs.
Reference: Nelson Textbook of Pediatrics, 22nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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