How to Give Levothyroxine to Your Baby

If the screening is positive, tests to determine levels of thyroid hormones in the blood (thyroid function tests) are done to confirm the diagnosis of hypothyroidism. If confirmed, newborns must be treated quickly to prevent developmental delays. In another rare cause, the pituitary gland is abnormally formed and fails to stimulate the thyroid gland to produce thyroid hormones. This pattern of thyroid abnormality also can develop in children who take certain medications (such as antiseizure medications and medications that help the body recognize and attack cancer cells) or who have certain illnesses.

Prognosis for Hypothyroidism in Infants and Children

• Symptoms in infants include poor feeding and growth failure; symptoms in older children and adolescents are similar to those of adults but also include growth failure, delayed puberty, or both.
• Hearing loss may be so mild that initial screening misses it, but it may still interfere with language acquisition.
• Doctors continue to monitor children by doing blood tests at regular intervals depending on their age.
• Rarely, delayed diagnosis and treatment of severe hypothyroidism lead to intellectual disability and short stature.

To date, there is limited experience with these liquid formulations in congenital hypothyroidism, and it is unclear whether dosing is the same as for crushed tablets. If levothyroxinemust be given intravenously, 75% of the oral dose should be used. Although T3 is the biologically active thyroid hormone, levothyroxine (T4) is usually given as monotherapy and it is not necessary to use T3 because the majority of brain T3 arises through enzyme conversion of T4 to T3. In children and adolescents with suspected hypothyroidism (elevated TSH and low T4/free T4), thyroid antibody titers (to thyroid peroxidase and thyroglobulin) should be measured to evaluate for autoimmune thyroiditis.

Is it OK To Switch Between Brands of Thyroid Hormone Medication?

The rare side effects of thyroid hormone medication are related to overdose, or too much medication, and can include rapid heart rate, sweating, anxiety, and tremors. If your child experiences these signs and symptoms, you should contact the physician who prescribed the medication for your child. A child will not have these problems if the thyroid hormone dose prescribed is only slightly more than is needed. Worldwide, the most common cause of hypothyroidism is iodine deficiency, but this cause is rare in the United States.

• Children who have other genetic conditions (such as DiGeorge syndrome or Prader-Willi syndrome) are at increased risk of acquired hypothyroidism that is not autoimmune.
• Thyroid hormone is the medication prescribed by your child’s doctor to treat hypothyroidism, also known as an underactive thyroid gland.
• Thyroid function tests are also done in older children and adolescents who doctors think may have hypothyroidism.
• Alternatively this pattern of thyroid dysfunction develops in children who use certain medications (eg, antiseizure medications, immune checkpoint inhibitors) or who have certain illnesses (euthyroid sick syndrome).

At first, newborns who have hypothyroidism that is caused by a problem with their thyroid gland usually have few if any symptoms because some thyroid hormone from the mother crosses the placenta. Once newborns no longer receive thyroid hormone from their mother, symptoms develop slowly and the disorder is detected only when they undergo newborn screening tests. Most children who have congenital hypothyroidism usually need to take thyroid hormone replacement for life. However, some children who have congenital hypothyroidism, usually those who have not required a dose increase after infancy, may be able to stop treatment after they are about 3 years of age. In congenital hypothyroidism,treatment with levothyroxine orally once a day must be started synthroid benadryl immediately and be closely monitored.

Acquired hypothyroidism

However, pregnant women in the United States can develop mild iodine deficiency because their bodies need more iodine when they are pregnant. Children whose diet is restricted because they have multiple food allergies or who are fed through a tube inserted into a vein (parenteral nutrition) may not eat enough of the proper foods and thus develop iodine deficiency. For both forms of hypothyroidism, the dose is titrated to maintain serum T4 and TSH levels within the normal range for age.

Severe congenital hypothyroidism, even when treated promptly, may still cause subtle developmental problems and sensorineural hearing loss (3, 4). Hearing loss may be so mild that initial screening misses it, but it may still interfere with language acquisition. For babies and small children, because there is no reliable liquid preparation, the pill should be crushed just before administration and mixed with a small volume of water, human (breast) milk, or formula. This mixture can be given to the baby or small child using a spoon, dropper, or infant syringe.

The spoon, dropper, or syringe should be “washed through” with more liquid 2 more times until all the thyroid hormone has been given. Making a mixture of crushed tablets and water or formula for storage is not recommended because this preparation is not stable. Some pharmacies will prepare a compounded suspension of levothyroxine, but it is only guaranteed to be stable for a month and it is more expensive. Other less common causes of acquired hypothyroidism include radiation therapy to the head and neck for certain cancers and the use of certain medications (for example, lithium or amiodarone).

• Brand names you may encounter for this medication include Levothroid, Levoxyl, Synthroid, and Unithroid.
• In acquired hypothyroidism, the usual starting dose of levothyroxine often depends on degree of hypothyroidism at diagnosis.
• Older children can be monitored more frequently if there are concerns about adherence.
• This pattern of thyroid abnormality also can develop in children who take certain medications (such as antiseizure medications and medications that help the body recognize and attack cancer cells) or who have certain illnesses.
• If levothyroxinemust be given intravenously, 75% of the oral dose should be used.
• If the newborn has an enlarged thyroid gland (congenital goiter), the gland may press against the windpipe and interfere with breathing.

For those who have an illness, thyroid function becomes normal once the illness goes away. Routine newborn screening detects hypothyroidism before clinical signs are evident (1). If screening is positive, confirmation is necessary with thyroid function tests, including measurement of free serum thyroxine (free T4) and thyroid-stimulating hormone (TSH) (2). Free T4 is a better measure of thyroid function than total T4 in these patients because the levels of thyroid-binding proteins (thyroid-binding globulin, transthyretin, and albumin) affect total T4 levels. It is particularly important to measure free T4 rather than total T4 in preterm or low birthweight infants in whom alterations in binding proteins lead to low total T4 levels despite normal free T4 levels.

If iodine deficiency occurs very early during pregnancy, newborns may have severe growth failure, abnormal facial features, intellectual disability, and stiff muscles that are difficult to move and control (called spasticity). If the underlying cause of hypothyroidism is not identified and hypothyroidism remains undiagnosed or untreated, brain development slows moderately to severely. If the newborn has an enlarged thyroid gland (congenital goiter), the gland may press against the windpipe and interfere with breathing.

Babies and older children also need thyroid hormone for normal growth, among other important body functions. In some countries, congenital hypothyroidism occurs when the mother does not get enough iodine in her diet while pregnant (iodine deficiency), and a woman’s body needs more iodine when she is pregnant. Iodine deficiency is rare in areas of the world where iodine is added to table salt but is more common in areas where people do not get enough iodine in their diet.