Abstract
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.
