[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Conditions](https://durgical.com/en/conditions/) › Congenital hypothyroidism [Conditions](https://durgical.com/en/conditions/) · [Pediatrics and neonatology](https://durgical.com/en/conditions/) # Congenital hypothyroidism A baby is born with too little thyroid hormone. Newborn screening finds it early, and daily hormone treatment prevents intellectual disability. Updated 2026-11-01 ## Structures involved Tap one to see what it is and open it in 3D. - [Thyroid gland](https://durgical.com/en/anatomy/thyroid-gland/) - [Pituitary gland](https://durgical.com/en/anatomy/pituitary-gland/) - [Hypothalamus](https://durgical.com/en/anatomy/hypothalamus/) - [Trachea](https://durgical.com/en/anatomy/trachea/) ## Why it happens - [Trisomies 21, 18 and 13, and the 22q11.2 deletion](https://durgical.com/en/general-pathology/trisomies-21-18-and-13-and-the-22q11-2-deletion/) - [Actions of thyroid hormones](https://durgical.com/en/physiology/actions-of-thyroid-hormones/) - [The thyroid axis: reading TSH and free T4](https://durgical.com/en/physiology/the-thyroid-axis-reading-tsh-and-free-t4/) - [Thyroid hormone synthesis](https://durgical.com/en/biochemistry/pathways/thyroid-hormone-synthesis/) - [Newborn screening](https://durgical.com/en/biochemistry/topics/newborn-screening/) - [Thyroid follicles, C cells and parathyroid](https://durgical.com/en/histology/thyroid-follicles-c-cells-and-parathyroid/) ## What it is Thyroid hormone deficiency present at birth, usually due to a missing, misplaced or underdeveloped [thyroid gland](https://durgical.com/en/anatomy/thyroid-gland/). It is the most common preventable cause of intellectual disability, which is why newborn screening exists. ## Who gets it Affects roughly 1 in 2,000 to 4,000 newborns worldwide. Colombia includes TSH in its newborn screening (umbilical cord or heel-prick blood), and Latin American programmes find similar rates. Iodine deficiency, once a cause of endemic cretinism in Andean areas, has been largely controlled by salt iodisation. ## Causes - Thyroid dysgenesis (most cases): ectopic gland (often sublingual), absent gland (agenesis) or a small gland - Dyshormonogenesis: inherited defects in hormone synthesis, often with goitre - Central (pituitary or hypothalamic) hypothyroidism, rarer - Transient forms: maternal antithyroid drugs or blocking antibodies, iodine deficiency or excess ## Risk factors - Female sex - Down syndrome and other congenital anomalies, including heart defects - Prematurity and low birth weight (delayed TSH rise) - Family history of dyshormonogenesis - Maternal thyroid disease or iodine deficiency ## Pathophysiology Thyroid hormone is essential for brain myelination and neuronal growth in the first years of life. Maternal thyroxine crosses the placenta partly, so most babies look normal at birth. After birth the deficit becomes clear: low thyroxine causes a high TSH (primary forms), slow metabolism and, if untreated, permanent damage to brain development and growth. ## Classification - Primary (thyroid) versus central (pituitary or hypothalamic) - Permanent versus transient - Dysgenesis versus dyshormonogenesis ## Symptoms and signs - Often no signs at birth; found on screening - Prolonged jaundice - Poor feeding, lethargy, little crying and excessive sleep - Constipation, hypotonia and hoarse cry - Large [tongue](https://durgical.com/en/anatomy/tongue/) (macroglossia), umbilical hernia and large anterior fontanelle - Dry, cold, mottled [skin](https://durgical.com/en/anatomy/skin/) and puffy face ## Red flags - Positive newborn screen: needs urgent confirmation and treatment - Prolonged neonatal jaundice with lethargy or poor feeding - Delayed development or growth in an infant not screened ## Diagnosis **Clinical** Most cases are detected by screening; clinical signs appear later and indicate delayed diagnosis. **Tests** Newborn TSH on cord or heel blood; a raised result is confirmed with serum TSH and free T4 (high TSH with low free T4 in primary forms). Thyroglobulin and thyroid antibodies help classify the cause. **Imaging** Thyroid ultrasound or scintigraphy to find an absent or ectopic gland, without delaying treatment. Knee X-ray may show delayed bone age. ## Differential diagnosis - Transient hyperthyrotropinaemia or maternal antibody effect - Central hypothyroidism or hypopituitarism - Other causes of prolonged neonatal jaundice - Down syndrome features without hypothyroidism ## Goal of treatment Normalise thyroid hormone as early as possible (ideally in the first two weeks of life) to protect brain development and growth. ## Treatment **Medical** Oral levothyroxine started as soon as the diagnosis is confirmed, with the dose adjusted to weight and laboratory results by the specialist. **Follow-up** Frequent TSH and free T4 checks during the first years, with dose adjustments as the child grows. **Follow-up** Follow-up of growth, development and hearing; reassessment at about 3 years to decide whether the condition is permanent or transient. ## Complications - Intellectual disability when treatment is late or absent - Short stature and delayed bone maturation - Neurodevelopmental, motor and hearing problems - Prolonged jaundice in the neonatal period ## Prognosis With early treatment and good adherence, growth and intelligence are usually normal. Each week of delay increases the risk of lasting cognitive impairment. ## Prevention - Universal newborn screening with TSH and prompt follow-up of positive results - Adequate iodine intake in pregnancy (iodised salt) - Management of maternal thyroid disease during pregnancy ## Test yourself Think of the answer, then tap the question to see it. ## What is the most common cause of congenital hypothyroidism? Thyroid dysgenesis, most often an ectopic (sublingual) gland, followed by agenesis or a small gland. ## Why do most babies with congenital hypothyroidism look normal at birth? Some maternal thyroxine crosses the placenta, and signs appear gradually after birth. ## Which test is used in newborn screening for congenital hypothyroidism? TSH from umbilical cord or heel-prick blood, confirmed with serum TSH and free T4. ## What is the treatment of congenital hypothyroidism? Oral levothyroxine started as early as possible, ideally within the first two weeks of life, with regular laboratory monitoring. ## Which three classic late signs suggest untreated congenital hypothyroidism? Prolonged jaundice, macroglossia and umbilical hernia (also hypotonia, constipation and a large fontanelle). [Add to my cards (5)](https://durgical.app/estudiar/?add=/en/conditions/congenital-hypothyroidism/) ## Related conditions - [Hypothyroidism](https://durgical.com/en/conditions/hypothyroidism/) - [Neonatal jaundice](https://durgical.com/en/conditions/neonatal-jaundice/) - [Down syndrome (trisomy 21)](https://durgical.com/en/conditions/down-syndrome/) - [Umbilical hernia](https://durgical.com/en/conditions/umbilical-hernia/) - [Hypopituitarism (incl. Sheehan syndrome and pituitary apoplexy)](https://durgical.com/en/conditions/hypopituitarism/) - [Goitre](https://durgical.com/en/conditions/goitre/) Educational information, not medical advice. For any symptom, see a health professional. Sources: [Neonatal hypothyroidism](https://medlineplus.gov/ency/article/001193.htm) (MedlinePlus (U.S. National Library of Medicine), 2024). [← All conditions](https://durgical.com/en/conditions/) ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/conditions/congenital-hypothyroidism/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/congenital-hypothyroidism/