How to Give Levothyroxine to Your Baby

Hypothyroidism also occurs as a result oftreatment for hyperthyroidism or for thyroid cancer. Congenital hypothyroidism occurs when the thyroid gland does not develop or function normally before birth. In acquired hypothyroidism, the usual starting dose of levothyroxine often depends on degree of hypothyroidism at diagnosis. For severe, longstanding hypothyroidism, lower starting doses may be selected to avoid potential behavioral symptoms with slower titration to full dosing. Thyroid ultrasonography is not necessary to establish the diagnosis of autoimmune thyroiditis and should be restricted to children with thyroid gland asymmetry or palpable thyroid nodules.

Most newborns who are treated have normal movement control and intellectual development.
Thyroid ultrasonography is not necessary to establish the diagnosis of autoimmune thyroiditis and should be restricted to children with thyroid gland asymmetry or palpable thyroid nodules.
Another rare cause is central hypothyroidism, which is caused by structural anomalies in pituitary development; patients usually also have other pituitary hormone deficiencies.
Ultrasonography may also be done in older children and adolescents if the thyroid gland feels asymmetric or the doctor feels a growth (nodule) on the thyroid gland.
Central hypothyroidism manifests with a pattern of low free T4 and non-elevated TSH levels.
Copyright © 2018 American Academy of Pediatrics and Pediatric Endocrine Society.

What Are the Side Effects of Thyroid Hormone Medication?

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 synthroid angioedema 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.

If you find out one day that the previous dose was missed, it is fine to double the dose the next day.
Hypothyroidism can occur in a developing fetus or newborn or during childhood or adolescence.
Rarely in the United States but commonly in countries where iodine is not routinely added to table salt, hypothyroidism results from maternal iodine deficiency.

Hypothyroidism in Infants and Children

However, pregnant women in the United States can develop mild iodine deficiency because theirbodies 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.

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).

Another rare cause is central hypothyroidism, which is caused by structural anomalies in pituitary development; patients usually also have other pituitary hormone deficiencies. Signs specific to children are growth retardation, delayed skeletal maturation, and usually delayed puberty. Autoimmune thyroiditis occurs most commonly during adolescence, but it also occurs in younger children, typically after the first few years of life. Children with trisomy 21 and Turner syndrome are at increased risk of autoimmune thyroid disease. Children with other genetic conditions (eg, DiGeorge syndrome, Prader-Willi syndrome) are at increased risk of acquired hypothyroidism that is not autoimmune.

Symptoms and Signs of Hypothyroidism in Infants and Children

Symptoms that do occur may be subtle or develop slowly because some maternal thyroid hormone crosses the placenta. Rarely, delayed diagnosis and treatment of severe hypothyroidism lead to intellectual disability and short stature. Permanent hypothyroidism is also the goal of therapy for patients undergoing definitive therapy for Graves disease (see treatment of hyperthyroidism in infants and children) or thyroid cancer. Rarely in the United States but commonly in countries where iodine is not routinely added to table salt, hypothyroidism results from maternal iodine deficiency. Rarely, transplacental transfer of antibodies, goitrogens (eg, amiodarone), or antithyroid medications (eg, propylthiouracil, methimazole) causes transient hypothyroidism.

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.

Treatment references

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.

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 immediately and be closely monitored.

Older children and adolescents

Iodine deficiency remains the most common worldwide cause of hypothyroidism in children but is rare in the United States. Iodine deficiency may occur in children whose diet is restricted because of multiple food allergies or in those who require long-term parenteral nutrition. Treatment of hypothyroidism is directed by a doctor who specializes in treating children with problems of the endocrine system (called a pediatric endocrinologist). Doctors continue to monitor children by doing blood tests at regular intervals depending on their age.