Paeds · endocrinology-diabetes-and-growth
Congenital hypothyroidism
Also known as congenital hypothyroidism · neonatal hypothyroidism · cretinism (historical) · primary congenital hypothyroidism · central congenital hypothyroidism
A fellowship approach to congenital hypothyroidism: the newborn-screening-to-treatment pipeline that prevents intellectual disability, the dose and timing of levothyroxine that protects the developing brain (10 to 15 mcg per kg per day, started within the first two weeks), the primary-versus-central classification that explains which babies the TSH screen misses, and the long-term surveillance and permanence reassessment that carries the child into adult endocrine care.
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- A low or borderline newborn TSH does not exclude central congenital hypothyroidism — the TSH screen misses central disease, so any neonate with a low free T4 and a pituitary or midline problem needs venous thyroid function tests
- Treatment must start within the first two weeks at 10 to 15 mcg per kg per day; a low starting dose or a delayed start is the commonest preventable cause of residual neurodevelopmental deficit
- Do not wait for thyroid imaging or genetic results before starting levothyroxine — confirm with venous thyroid function tests and treat the same day
- Free T4 should normalise within two weeks and TSH within four weeks; a persistently high TSH on a correct dose means non-adherence or malabsorption, not a need for endless dose escalation
- An abnormal thyroid function test in a treated infant most often means the dose has not kept up with growth — re-weigh, re-dose, re-check
- Premature, low-birth-weight, and twin infants have a delayed TSH rise and may have false-negative early screens — repeat screening is required
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- General and Community Paediatrics
- Endocrinology and diabetes
- Growth and Development
- Endocrinology - recognise, investigate and manage congenital hypothyroidism and other thyroid disorders
- Neonatal medicine - interpret newborn screening and initiate management
- Renewed curriculum for first-year trainees from 2027 - Learning goal 6: Clinical management - essential general paediatrics
- Endocrinology 10-12
- Neonatal medicine 10-12
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- 5. Endocrinology and growth - thyroid disorders
- 1. Neonates and infants with endocrinology: congenital hypothyroidism
- 4. Professional skills and knowledge: Patient management
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- Patient Care 5: Patient Management
- Medical Knowledge 1: Congenital anomalies and genetics
- Systems-Based Practice 1: Patient Safety
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- Pediatrics: Endocrinology applied domain
A well baby is flagged on the newborn bloodspot screen at day four with a raised TSH; or a midwife notices prolonged jaundice, a large posterior fontanelle, and a sleepy, constipated two-week-old; or a premature twin returns a falsely reassuring early screen and presents at six weeks with failure to thrive. The fellowship task in each is the same: confirm, treat at full dose within two weeks, and build the surveillance net that carries the brain through its critical first thousand days. [3] [4]
Remember the pipeline as four moves. Confirm with venous TSH and free T4 before day 14. Treat with levothyroxine 10 to 15 mcg per kg per day. Monitor free T4 and TSH at two and four weeks, then frequently through infancy. Reassess permanence with a trial off therapy at age three, unless the gland is ectopic or the starting dose was high. Miss any move and the pipeline leaks — a delayed or under-dosed start is the commonest preventable cause of residual neurodevelopmental deficit. [1] [5]
Overview & Definition
Congenital hypothyroidism is the deficiency of thyroid hormone that is present at birth, whether because the gland never formed, formed in the wrong place, formed but cannot make hormone, or is not being driven by an intact pituitary axis. It is one of the commonest preventable causes of intellectual disability, and the entire machinery of newborn screening was built to detect it in the asymptomatic first weeks, before the clinical picture declares itself. [4] [9]
The historical name — cretinism — described the untreated end-state: severe intellectual disability, deafness, spasticity, and the coarse features and growth failure that gave the condition its name. That end-state is now a failure of the screening programme, not an expected outcome, because early and adequate levothyroxine restores the developmental trajectory. The disease itself has not changed, but the clinical task has shifted from rescuing a brain-damaged child to running a reliable pipeline that keeps the thyroid axis normal from the first week of life. [9] [7]
What has not changed is biology screening protects against. Thyroid hormone, as T3, drives myelination, synaptogenesis, and neuronal migration through the first thousand days, and the fetal and neonatal brain are wholly dependent on it. A baby whose thyroid hormone is low through that window pays a cognitive cost that is hard to recover, which is why the dose, the timing, and the adherence matter more than any other detail in the topic. [10] [1]
References10ShowHide
- [1]van Trotsenburg P, Stoupa A, Léger J, et al. Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology. Thyroid, 2021.PMID 33272083
- [2]Léger J, Olivieri A, Donaldson M, et al. European Society for Paediatric Endocrinology consensus guidelines on screening, diagnosis, and management of congenital hypothyroidism. J Clin Endocrinol Metab, 2014.PMID 24446653
- [3]Rose SR, Brown RS, Foley T, et al. Update of newborn screening and therapy for congenital hypothyroidism. Pediatrics, 2006.PMID 16740880
- [4]Rastogi MV, LaFranchi SH. Congenital hypothyroidism. Orphanet J Rare Dis, 2010.PMID 20537182
- [5]Hrytsiuk I, Gilbert R, Logan S, Pindoria S, Brook CG. Starting dose of levothyroxine for the treatment of congenital hypothyroidism: a systematic review. Arch Pediatr Adolesc Med, 2002.PMID 11980555
- [6]Albert BB, Heather N, Derraik JG, et al. Neurodevelopmental and body composition outcomes in children with congenital hypothyroidism treated with high-dose initial replacement and close monitoring. J Clin Endocrinol Metab, 2013.PMID 23861458
- [7]Kempers MJ, van der Sluijs Veer L, Nijhuis-van der Sanden RW, Kooistra L, Wiedijk BM, Faber I, Last BF, de Vijlder JJ, Grootenhuis MA, Vulsma T. Intellectual and motor development of young adults with congenital hypothyroidism diagnosed by neonatal screening. J Clin Endocrinol Metab, 2006.PMID 16303842
- [8]Kempers MJ, van der Sluijs Veer L, Nijhuis-van der Sanden RW, et al. Neonatal screening for congenital hypothyroidism in the Netherlands: cognitive and motor outcome at 10 years of age. J Clin Endocrinol Metab, 2007.PMID 17164300
- [9]Grosse SD, Van Vliet G. Prevention of intellectual disability through screening for congenital hypothyroidism: how much and at what level? Arch Dis Child, 2011.PMID 21242230
- [10]Raymond J, LaFranchi SH. Fetal and neonatal thyroid function: review and summary of significant new findings. Curr Opin Endocrinol Diabetes Obes, 2010.PMID 19901830