Newborn Thyroid Screening
Newborn screening for congenital hypothyroidism is one of the great success stories of preventive medicine. Babies are tested shortly after birth so that an underactive thyroid can be treated before it affects brain development.
The test is quick, uses a few drops of blood, and is offered to all newborns in most health systems.
Last medically reviewed: 15 November 2025
Why it matters
Thyroid hormone is essential for brain and physical development in early life. A baby born without enough thyroid hormone may show few signs at first, yet delays can become permanent if treatment is late.
Detecting and treating congenital hypothyroidism within the first weeks of life allows normal development in most cases.
How the test is done
A few drops of blood are collected from a heel prick, usually on the second to fifth day of life, and tested for TSH and sometimes T4. The result is available within days.
If the screen is abnormal, further tests confirm the diagnosis and treatment is started promptly.
If treatment is needed
Congenital hypothyroidism is treated with levothyroxine, started as early as possible. Regular monitoring and dose adjustment continue through childhood to support growth and development.
With early treatment, most children develop normally.
Frequently asked questions
Why is newborn thyroid screening done?
It detects congenital hypothyroidism early, before it can affect brain development, so treatment can begin within the first weeks of life.
How is the sample taken?
A few drops of blood are taken by a heel prick, usually in the first few days after birth.
What if the result is abnormal?
Further tests confirm the diagnosis and treatment with levothyroxine is started promptly. Early treatment allows normal development in most cases.
References & further reading
This page is based on established medical knowledge and guidelines from authoritative sources. Always consult a qualified clinician for personal medical advice.
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