Congenital Hypothyroidism

Congenital hypothyroidism is a thyroid hormone deficiency disorder present at birth due to thyroid gland failure. There are two types: primary and central. Primary congenital hypothyroidism is caused by either developmental disorders of the thyroid gland or defects in thyroid hormone synthesis. The central type, which is much less common, is caused by decreased TSH secretion or bioactivity. Thyroid dysgenesis and dyshormonogenesis are the major causes of congenital hypothyroidism. Most cases are multifactorial, involving several genes, and a small percentage is monogenic. Thyroid failure occurs prenatally, but maternal thyroid hormones may prevent fetal hypothyroidism and protect the brain. Untreated congenital hypothyroidism severely affects postnatal development, but neonatal screening allows for early thyroid hormone treatment, effectively preventing hypothyroidism.