Hyperthyroidism in infants is rare but potentially serious. It is often a temporary condition that has associations with maternal Graves’ disease.

Graves’ disease is an autoimmune condition that causes the body to produce antibodies that stimulate the thyroid gland and its production of thyroid hormone. During pregnancy, these antibodies can pass to the fetus via the placenta and cause increased thyroid production in the fetus.

In most cases, doctors consider hyperthyroidism in infants to be transient hyperthyroidism, meaning it is temporary.

Read on to learn more about hyperthyroidism in infants.

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Symptoms relating to hyperthyroidism in infants and maternal Graves’ disease usually develop in the weeks after birth and can include:

  • irritability
  • sleep disorders
  • flushing
  • sweating
  • difficulty breathing
  • a lump or swelling at the front of the beck
  • diarrhea
  • bulging eyes
  • feeding difficulties
  • jaundice, which involves a yellowing of the skin and eyes

Thyroid hormone is essential for central nervous system function and typical brain development. Therefore, hyperthyroidism in infants can increase the risk of health and developmental issues, including conditions such as intellectual disabilities, lack of growth, and hyperactivity.

There are several causes of hyperthyroidism in infants. However, the most common reason is maternal Graves’ disease. The condition arises when antibodies pass to the fetus during pregnancy, leading to increased thyroid production in the infant.

While this is potentially a serious condition that needs careful monitoring and, in some cases, treatment, it is temporary.

Infants with hyperthyroidism are usually symptom-free in the first weeks of life. However, a parent or caregiver may notice symptoms as the condition progresses.

Therefore, diagnosis often relies on testing. Most countries worldwide test all infants soon after birth.

One test that can diagnose thyroid dysfunction is known as the heel prick test. This involves taking a small amount of blood from the infant’s heel, which a medical professional tests for thyroid stimulating hormone. A doctor may order further blood tests if necessary.

However, newborn screening for hyperthyroidism is not standard. Doctors will check for the condition according to an infant’s symptoms, paternal history, or both.

If doctors have identified a risk of maternal Graves’ disease, healthcare professionals will closely monitor the infant. They will also conduct blood tests measuring thyroid hormones.

Only a small number of infants who are at risk will develop maternal Graves’ disease. Health experts estimate that the condition affects 1–5% of infants born to women with Graves’ disease.

Treatment for hyperthyroidism in infants may include drugs to manage thyroid hormone production. Examples of these include antithyroid drugs, such as methimazole and carbimazole. Doctors may also recommend drugs to manage symptoms. These can include beta-blockers to manage heart rate.

Most often, these treatments will be short term. Graves’ disease usually resolves within 3–12 weeks as the parental antibodies clear from the infant.

In older children, symptoms may relapse or persist, and long-term treatment may be necessary.

If there is a history of Graves’ disease in the birthing parent, a person can discuss this with a doctor. They can conduct any necessary tests to establish if there is a risk to the infant.

Anybody with concerns about an infant’s health can contact a doctor.

Hyperthyroidism in infants is a rare but potentially serious condition. It most often has links to maternal Graves’ disease.

Doctors can detect the condition by testing an infant soon after birth.

Treatment options include symptom management and drugs to reduce thyroid hormone production. The majority of cases resolve within 3–12 weeks.