Thyroid & parathyroid

Thyroid endocrine abnormalities

Congenital hypothyroidism

Last author update: 1 July 2016
Last staff update: 19 February 2021

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PubMed Search: hypothyroidism cretinism

See also Aplasia / hypoplasia, Dyshormonogenetic goiter, Screening - Neonatal hypothyroidism

Anthony Chi, M.D., Ph.D.
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Cite this page: Chi A, Guilmette J. Congenital hypothyroidism. website. Accessed September 22nd, 2023.
Definition / general
  • Also called cretinism
  • Congenital hypothyroidism (CH) is a clinical condition characterized by absence of thyroid hormone secondary to abnormal thyroid gland developmental or biosynthesis disorders (J Coll Physicians Surg Pak 2013;23:214)
  • This topic also contains links to its two causes, Aplasia / hypoplasia and Dyshormonogenetic goiter
  • Congenital hypothyroidism is now treatable due to newborn testing, iodine supplementation and hormone replacement therapy (Pediatrics 2006;117:2290)
  • The consequence of untreated CH is a constellation of physical and mental conditions, called cretinism
  • The incidence of congenital hypothyroidism has been increasing in the U.S. since mandated screening began (Mol Genet Metab 2007;91:268)
Essential features
  • Congenital hypothyroidism (CH) is a preventable cause of intellectual disability (formerly mental retardation), usually caused by thyroid gland dysgenesis or agenesis
  • Rarely, CH may result from a pituitary or hypothalamic abnormality (Pediatrics 2006;117:2290)
  • Occasionally newborn thyroid abnormalities, including CH, are due to transplacental passage of medication, blocking antibodies or iodine excess / deficiency from the mother; in these cases, the abnormality is often transient (Pediatrics 2006;117:2290)
  • National screening programs allow early diagnosis and treatment (Iran J Pediatr 2014;24:665)
  • Clinically, signs and symptoms related to CH arise in early infancy and include impaired skeletal development, dwarfism, intellectual disability and GU congenital malformation (J Pediatr 2009;154:263)
  • Histological examination reveals variably size nodules with microfollicular, solid predominant and macrofollicular patterns
  • Follicular cytological atypia may be observed (Diagn Cytopathol 2013;41:720, Ann Transl Med 2013;1:21)
  • See also sections in these topics: Aplasia / hypoplasia and Dyshormonogenetic goiter
  • Maternal hypothyroidism may cause severe mental retardation, because maternal T3 / T4 crosses the placenta and is critical to support fetal brain development before the fetal thyroid gland develops
  • Two types of congenital hypothyroidism are described (Endocr Dev 2014;26:60):
    • Thyroid dysgenesis (TD) results in a thyroid organogenesis defect
      • Mutations identified in these genes: TSHR, PAX8, NKX2-1, FOXE1 and NKX2-5
    • Thyroid dyshormonogenesis affects overall thyroid hormone synthesis
      • Mutations cause iodine organification defects (TPO, DUOX2, DUOXA2, SLC26A4), iodine transport defect (SLC5A5), thyroglobulin (TG) synthesis or transport defect or iodotyrosine deiodinase (IYD / DEHAL1) deficiency
  • Usually due to thyroid dysgenesis / agenesis, rarely due to inborn errors of metabolism
  • 2% of patients with CH have a positive family history
  • This disorder is usually considered to be sporadic (J Clin Endocrinol Metab 2001;86:2009)
Clinical features
Radiology description
Case reports
Gross description
Microscopic (histologic) description
Cytology description
Differential diagnosis
Additional references
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