Congenital hypothyroidism

Congenital hypothyroidism (CHT), previously known as cretinism, can be of thyroidal or central (hypothalamic/pituitary) origin and can have a widely diverse molecular aetiology.

Clinical presentation

Most children are asymptomatic at birth and are diagnosed after screening. In untreated congenital hypothyroidism, patients can present with short stature, disproportionately enlarged heads, and/or developmental delay / intellectual disability ⁵.

Pathology

Aetiology

• disorders in development of the thyroid gland
  • thyroid is absent
  • underdevelopment with migration failure
  • underdevelopment with normal migration
  • certain fetal goitres can also give hypothyroidism ⁴
• disorders in thyroid hormone synthesis
  • TSH hyporesponsiveness
  • defects in iodide transport from circulation into the thyroidcell
  • defects in iodide transport from the thyroid cell to thefollicular lumen, often combined with inner ear deafness(Pendred syndrome)
  • defects in the synthesis of hydrogen peroxide
  • defects in the oxidation of iodide, iodination andiodothyronine synthesis
  • defects in processes involved in the synthesis or degradation of thyroglobulin
  • detects in iodine recycling
• central congenital hypothyroidism
  • disorders in development and/or function of the
    • hypothalamus
    • pituitary gland
    • both

Radiographic features

Plain radiograph

• delayed skeletal maturation
  • bone age can be assessed by the Greulich & Pyle method with a PA left hand radiograph
• bone epiphyses/ossification centres are absent or small
  • stippled epiphysis appearance
• cortical thickening