Treatment of Congenital Hypothyroidism in Infants and Children

newborn baby boy in hospital bassinette
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Congenital hypothyroidism refers to hypothyroidism,  a deficiency or lack of thyroid hormone, that is present at birth. Thanks to modern science, sophisticated newborn screening has made congenital hypothyroidism very rare. Still, if it is present, it is especially important that it be quickly diagnosed and properly treated in newborns and infants, as thyroid levels are a factor in cognitive development and IQ.

Treatment of Congenital Hypothyroidism

Typically, levothyroxine, a synthetic form of the thyroid hormone T4, is used to treat congenital hypothyroidism. In an infant diagnosed with congenital hypothyroidism, the objective is to give thyroid hormone replacement medication to return the T4 levels to the normal range.

According to online medical journal UpToDate :

"Both the timing and dose of thyroid hormone replacement are important [3-5]. The initial goal of treatment should be to restore the serum T4 concentration to >10 mcg/dL (>129 nmol/L) as rapidly as possible. In one study, patients who took longer than two weeks to normalize their thyroid function had lower cognitive, attention, and achievement scores than those who achieved normal function within two weeks after therapy was started.
In a literature review identifying 11 studies evaluating the age of onset of thyroid hormone treatment, infants started "early" (12 to 30 days of age) had a mean IQ 15.7 points higher than infants started "later" (>30 days of age)...Rapid replacement with adequate doses of T4 is particularly important in infants with severe hypothyroidism.
This was illustrated in a study of 61 infants with [severe] congenital hypothyroidism...only those treated early with high-dose T4 achieved normal psychomotor development at 10 to 30 months. In infants with mild hypothyroidism, all achieved normal psychomotor development except for those treated late with a low starting dose."

Clearly, as the UpToDate excerpt explains, when congenital hypothyroidism is identified, the objective of physicians and parents is to restore thyroid levels to normal as quickly and safely as possible. The more quickly the thyroid levels are normalized, the more normal the cognitive and motor skills development of the infant.

Administering Thyroid Medication to Infants With Congenital Hypothyroidism

Talk to your doctor about getting a liquid form of levothyroxine to administer to infants. 

To give levothyroxine tablets to an infant, parents should crush the levothyroxine tablet and mix it with breast milk, formula, or water that's fed to the baby.

An important note for parents, however: Don't mix the levothyroxine with soy infant formula or any calcium or iron-fortified preparations. Soy, calcium, and iron can all reduce the infant's ability to absorb the medication properly.

Because soy formula itself can slow or impair an infant's ability to reach normal thyroid levels, it's recommended that infants with congenital hypothyroidism who are fed soy formula be monitored regularly and closely. They may require an increased dose of medication in order to achieve normal thyroid levels and protect their neurological development.

Treating Congenital Hypothyroidism

Children being treated for congenital hypothyroidism should be evaluated on a regular schedule, and should be evaluated every several months for at least the first three years of life. UpToDate reports that, according to the American Academy of Pediatrics, serum T4 or free T4 and TSH blood tests should be performed according to the following schedule:

  • At 2 and 4 weeks after the initiation of T4 treatment
  • Every 1 to 2 months during the first 6 months of life
  • Every 3 to 4 months between 6 months and 3 years of age
  • Every 6 to 12 months thereafter until growth is complete
  • Two weeks after any change in dose
  • At more frequent intervals when compliance is questioned or abnormal results are obtained

Permanent or lifelong congenital hypothyroidism can be established by imaging and ultrasound studies showing that the thyroid is missing or ectopic, or a defect in the ability to synthesize and/or secrete thyroid hormone is confirmed.

A Word from Verywell

If permanent hypothyroidism has not been established, levothyroxine treatment can be discontinued for a month at age 3, and the child retested. If levels remain normal, transient hypothyroidism is presumed. If levels become abnormal, permanent hypothyroidism is assumed.

Children with transient congenital hypothyroidism who are taken off medication should, however, still have periodic thyroid evaluation and retesting, as these children face an increased risk of developing a thyroid problem throughout their lives.


LaFranchi, Stephen. "Treatment and prognosis of congenital hypothyroidism." UpToDate. Accessed: January 2009.