Congenital hypothyroidism

For family education. This resource is not an individual diagnosis or treatment plan. Discuss concerns with an appropriately qualified professional.

What it means

Congenital hypothyroidism means inadequate thyroid hormone production or action from birth. Thyroid hormone is important for growth and brain development. Babies may initially show few symptoms, making newborn screening valuable. Prompt confirmation and treatment can greatly reduce developmental risk, with continued monitoring needed during growth.

Causes and risk factors

Common causes include a thyroid gland that is absent, underdeveloped, or in an unusual location, and difficulties making thyroid hormone. Some causes are genetic; others are temporary. Less common forms involve hormone-control systems. The clinical team determines whether treatment is likely to be lifelong or temporary.

Signs and everyday impact

A newborn may appear well despite low thyroid hormone. Possible signs include prolonged jaundice, unusual sleepiness, poor feeding, constipation, low muscle tone, or slower growth. Waiting for obvious symptoms can delay care. Later developmental concerns should still be assessed even after an earlier screening result.

Assessment and diagnosis

An abnormal newborn screen requires timely confirmatory thyroid blood tests and clinical review. Screening is not a final diagnosis, and uncommon forms may not be detected by every screening program. A specialist determines the cause when useful and plans repeat tests to monitor treatment and growth.

Treatment and therapy

Treatment usually involves prompt thyroid hormone replacement with levothyroxine, prescribed and adjusted by the clinical team. Blood tests guide dosing as the child grows. Families receive instructions on administration and factors that affect absorption. Developmental assessment and early support are added when needed. Do not change the dose or stop treatment without medical advice.

Support at home

Give the prescribed medicine consistently using the team's instructions. Ask how feeding, other medicines, or supplements may affect administration. Keep blood-test appointments and discuss missed doses promptly. Track growth and developmental progress, and seek additional support when concerns arise rather than assuming treatment removes every possible difficulty.

When to seek help

Contact the clinical team promptly after an abnormal newborn screening result; do not wait for symptoms. Poor feeding, marked lethargy, worsening jaundice, or serious illness in a newborn requires urgent assessment.

Questions for the care team

• When are confirmatory tests and treatment needed?
• How should we give medicine and arrange monitoring?
• Is this likely to be permanent or temporary?

Terms in plain language

• Thyroid hormone: a hormone supporting growth, metabolism, and development.
• TSH: a hormone that helps regulate thyroid function.
• Newborn screening: testing that identifies babies who need further assessment.

Podcast preparation

Use this resource to prepare a later episode: define the topic, discuss causes and signs, explain assessment, describe treatment and home supports, then close with urgent signs and a next step.

Myth: a baby who looks well cannot have hypothyroidism. Screening can detect it before symptoms develop.

Verify current clinical guidance and obtain clinical review before public recording.

Sources

1. Congenital Hypothyroidism | Newborn Screening - https://newbornscreening.hrsa.gov/conditions/congenital-hypothyroidism
2. Congenital Hypothyroidism: Screening and Management - PubMed - https://pubmed.ncbi.nlm.nih.gov/36827521/
3. Assessing Developmental Delays in Children - HealthyChildren.org - https://www.healthychildren.org/English/ages-stages/toddler/Pages/Assessing-Developmental-Delays.aspx

Sources accessed 3 October 2026.