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Key messages

  • Transient disorders of thyroid function are more common in neonates than true congenital hypothyroidism.
  • Neonates with decreased thyroid function may also present with jaundice.
  • Thyroxine replacement therapy should be commenced as soon as congenital hypothyroidism is confirmed.
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    In June 2023, we commenced a project to review and update the Maternity and Neonatal eHandbook guidelines with a view to completion in 2024. Please be aware that pending this review, some of the current guidelines may be out of date. In the meantime, we recommend that you also refer to more contemporaneous evidence.

    Hypothyroidism in neonates is characterised by decreased thyroid hormone production, in rare cases no thyroid hormones are produced.

    Transient disorders of thyroid function are more common than true congenital hypothyroidism, especially in preterm infants.

    When thyroid-stimulating hormone (TSH) levels are elevated treatment with thyroxine (either long or short term) is usually indicated.

    Congenital hypothyroidism

    In Australia the incidence of congenital hypothyroidism is 1:3000-3600 with some geographic variation.

    Causes and incidence of hypothyroidism:

    • 75 per cent due to dysgenesis (gland development)
      • agenesis
      • ectopia
    • 10 per cent due to dyshormonogenesis (thyroid hormone biosynthesis)
      • often autosomal recessive
      • Pendred's syndrome = peroxidase deficiency associated with sensorineural deafness
    • 5 per cent due to hypothalamic-pituitary (H-P) deficiency
      • secondary hypothyroidism
      • tertiary hypothyroidism
    • 10 per cent due to intrauterine causes
      • iodine exposure
      • maternal antithyroid antibodies.


    Issues to note regarding the presentation of hypothyroidism:

    • The usual mode of presentation is by the finding of an elevated TSH detected on the newborn screening test (NST) taken at 48-72 hours (except in secondary or tertiary disease).
    • Neonates are often subclinically affected and only detected on routine newborn screening.
    • Clinical features may include:
      • dry skin
      • hoarse cry
      • constipation
      • puffy face
      • prominent tongue
      • listless
      • umbilical hernia
      • hypothermia
      • bradycardia
      • failure to thrive.
    • Neonates may also present with jaundice due to an unconjugated hyperbilirubinaemia (glucronyl transferase deficiency).
    • Gene mutations have been implicated in all forms of congenital hypothyroidism and in some cases result in an expanded phenotype including respiratory distress, choanal atresia, renal malformation and mental delay (independent of degree of hypothyroidism).


    History and examination

    When hypothyroidism is suspected or confirmed check for:

    • mother - diet, medication history, autoimmune disease
    • baby - signs and symptoms of congenital hypothyroidism, jaundice, goitre, growth parameters or other congenital problems.


    Investigation for hypothyroidism

    Confirmatory investigations include:

    • T4 and TSH levels
    • serum bilirubin (SBR) if clinically indicated
    • thyroid scan (showing absent, lingual or increased uptake of radioisotope).

    Management of hypothyroidism

    Management guidelines for hypothyroidismin:

    • Refer patients to the endocrine team.
    • Thyroxine replacement therapy should be commenced as soon congenital hypothyroidism confirmed at a dose of 8-10 ug/kg/day in a single daily dose.
    • Tablets should be ground up between two teaspoons and mixed with a few drops of milk. This solution should be transferred to a small, plastic feeding spoon and deposited on the back of the tongue immediately prior to feeds.
    • Prepared suspensions of thyroxine are not stable.
    • Dosage is adjusted according to TFT’s aiming to keep T4 at the upper end of normal and TSH in the normal range.


    The prognosis for infants with hypothyroidism:

    • The prognosis is usually one of normal intellectual and physical development if treatment is commenced promptly and monitored closely.
    • Over treatment may result in craniosynostosis and has been implicated in causing attention deficit hyperactivity disorder.


    Follow-up guidelines for infants with hypothyroidism:

    • Follow-up should occur at two weeks, six weeks, three months then every two-three months for first year.
    • TFTs repeated at each visit and dosage of thyroxine adjusted as required.
    • Growth and development must be closely monitored.
    • Hearing tests should be done at four to eight weeks then three-monthly for first year if dyshormonogenesis.
    • Developmental assessment performed as clinically indicated.

    Transient neonatal hypothyroidism

    Transient neonatal hypothyroidism is a group of conditions that can be subdivided into four main categories. Cause and biochemical profiles are listed in the table below. The four categories are:

    1. Transient hypothyroxinaemia:
      • low serum T4 levels seen in approx. 50 per cent of infants delivered before 30 weeks' gestation
      • normal or low TSH levels
      • corrects spontaneously over four to eight weeks
      • no treatment required
    2. Transient primary hypothyroidism
      • low serum T4 levels and high TSH levels
      • seen in approx. 20 per cent of premature infants (incidence increases as gestation decreases)
      • usually develops within one to two weeks after birth and often superimposed upon transient hypothyroxinaemia
      • Repeated screening cards should be sent on all infants < 1500 g. It is recommended test be repeated two weeks after birth in babies 1000-1500 g and at four weeks in those < 1000 g.
      • hypothyroidism may persist for two to three months
      • treatment recommended
    3. Transient hyperthyrotropinaemia
      • rare (one in 16-19,000 births)
      • elevated TSH for three to nine months before reducing spontaneously
      • no treatment required but need careful follow-up to exclude partial dyshormonogenesis or ectopia
    4. Low T3/T4 syndrome ('sick euthyroid')
      • non-thyroidal illness
      • no treatment required.
      T3 T4 TSH

    Low T3 syndrome



    Low T4 syndrome


    Causes and biochemical profiles of transient neonatal hypothyroidism








    Transient hypothyroxinaemia


    Immaturity of H-P axis (<30 weeks gestation)

    Transient primary

    Maternal anti-hypothyroidism thyroid therapy,
    iodine deficiency, maternal antibodies, idiopathic

    Transient hyperthyrotropinaemia


    Erroneous assay, iodine deficiency or excess, idiopathic

    Low T3/T4 syndrome



    Prematurity (in preterm infants), surgical stress,
    sepsis, malnutrition

    More information


    Orphanet Journal of Rare Diseases (2010) Congenital hypothyroidism

    Further reading

    • Pediatric Endocrinology Sperling MA, WB Saunders 1996, Philadelphia
    • Australasian Paediatric Endocrine Group; Guidelines for Management of Congenital Hypothyroidism
    • Smith Liz Updated AAP guidelines on Newborn screening and therapy for Congenital Hypothyroidism. Am Fam Physician, 2007 Aug 1;76(3); 439-444

    Get in touch

    Clinical Guidance Team
    Safer Care Victoria

    Version history

    First published: April 2016
    Review by: April 2019

    Uncontrolled when downloaded
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