What is Hypothyroidism?

The thyroid gland is a critical part of the endocrine (hormonal) system. It manufactures and releases thyroid hormones into the bloodstream that travel throughout the body and act on various tissues throughout the body. The thyroid interacts with other endocrine organs/glands. This complex interplay of signals is coordinated by the brain and influenced by several vitamins, nutrients, and other hormones.

The hypothalamus is a gland found in the brain that is responsible for managing hunger, thirst, sleep, hormones, and body temperature. It also monitors the thyroid hormone levels present in the blood. When it senses the need for increased energy and metabolism, it releases TRH (Thyroid Releasing Hormone) to tell the pituitary gland, also in your brain, to release Thyroid Stimulating Hormone (TSH).

TSH impacts the thyroid directly, stimulating it to manufacture and release thyroid hormones. To do this, the thyroid uses tyrosine (the amino acid) and iodine for the production and conversion of thyroid hormones. Specifically, T4, an inactive form of thyroid hormone that circulates via the blood and is stored in various tissues for when it’s needed, and T3, the active form of thyroid hormone.

When different body parts need active T3, they can convert inactive T4 to active T3 using deiodinase, an enzyme. Then, T3 can act on cells to stimulate energy production and regulate metabolism.

Hypothyroidism refers to an underactive or absent thyroid gland. Hypothyroidism happens when the thyroid does not make enough thyroid hormone to keep the body and metabolism running normally. Hypothyroidism can result in an infant when the thyroid gland is absent or underactive, not producing enough thyroid hormones, or when thyroid hormones cannot work properly in the peripheral tissues.

How Common is Hypothyroidism in Infants?

The incidence of hypothyroidism in infants varies by geographic location and population group. Around 10-15% of cases of hypothyroidism in children are due to congenital defects in the thyroid gland, where an infant is born without adequate thyroid function. Overall, one out of every 4,000 to 5,000 infants in the USA is born with congenital hypothyroidism.

Some studies suggest that congenital hypothyroidism is somewhat more common in the Hispanic and Asian populations compared to Whites and Blacks. This condition also seems more common in twin and other multiple births than singletons and preterm versus term infants.

Females are affected two times as frequently as males, and infants with chromosomal disorders such as Down, Williams, or Turner syndrome are at a greater risk of hypothyroidism.

Hypothyroidism in Infants Symptoms

The types of symptoms that develop in an infant with hypothyroidism depend on the cause and severity of the hormonal issue.

Neonates who experience fetal iodine deficiency very early during gestation may present as infants with

• severe growth failure
• intellectual disability
• spasticity

These babies with severe hypothyroidism may have a unique appearance, including

• coarse facial features
• dull look
• puffy face
• a thick tongue that sticks out

In cases due to other causes, infants with hypothyroidism may have less noticeable symptoms or only be diagnosed via newborn screenings. Any symptoms of hypothyroidism in these infants may be subtle or develop slowly because some maternal thyroid hormones cross the placenta. As the maternal thyroid hormone is metabolized, undiagnosed or untreated neonatal hypothyroidism can slow central nervous system development moderately to severely and may cause symptoms, including

• low muscle tone (floppy infant)
• sensorineural hearing loss
• prolonged hyperbilirubinemia that can cause yellowing of the skin and eyes (jaundice)
• umbilical hernia
• respiratory distress
• large fontanelles
• poor feeding and choking episodes
• dry, brittle hair
• constipation
• sleepiness or sluggishness
• hoarse crying

If diagnosis and treatment of severe hypothyroidism are delayed, it can lead to significant intellectual disability and short stature.

What Causes Hypothyroidism in Infants?

Hypothyroidism can happen for several reasons. Sometimes, an infant is born without a thyroid gland or an underactive thyroid gland, a condition known as congenital hypothyroidism. The most common cause of permanent congenital hypothyroidism in infants is thyroid dysgenesis, where the thyroid is missing, ectopic, or severely underdeveloped and cannot make a normal amount of hormones. Other causes of congenital hypothyroidism include an underdeveloped thyroid gland (thyroid hypoplasia) or a completely missing thyroid gland (thyroid agenesis). Permanent hypothyroidism can also occur due to inborn errors in thyroid hormone biosynthesis (dyshormonogenesis).

In other cases, a mother with the autoimmune condition Hashimoto’s thyroiditis can pass “thyroid-blocking antibodies” to the baby during pregnancy. This form of congenital hypothyroidism is often temporary, lasting a few weeks to months, during which time the baby may receive thyroid hormone replacement to treat the condition.

Similarly, mothers taking anti-thyroid medications like methimazole or propylthiouracil for hyperthyroidism or Graves’ disease or who ingest extremely high doses of iodine from the diet or a supplement can pass these medications across the placenta and cause transient hypothyroidism in the infant. On the other hand, maternal iodine deficiency can also cause hypothyroidism in the newborn and is most common in countries where iodine is not routinely added to table salt.

In other cases, the pituitary gland can malfunction and not send enough Thyroid Stimulating Hormone (TSH) to the thyroid gland. In other cases, TSH levels can be normal, yet the thyroid does not produce enough T4 and T3 to adequately stimulate cells due to nutritional deficiencies, malfunction, or other factors. Another potential way hypothyroidism can develop is if the peripheral receptors do not respond properly to thyroid hormones.

Functional Medicine Labs to Test for Root Cause of Hypothyroidism in Infants

Functional medicine testing can diagnose hypothyroidism in infants and help to identify the underlying causes, which can be addressed to help restore balance to the body. This includes assessing the overall functioning of the thyroid by looking at various hormone levels, measuring thyroid-supporting nutrients, and evaluating antibodies and other factors that affect immune system function to discover the causes of the autoimmunity that may be leading to Hashimoto’s disease.

Thyroid Function and Autoantibodies Testing

By law, all newborn babies are screened in the first few days of life with blood tests to look for serious diseases, including measuring thyroid function. Premature infants may require repeat thyroid function testing a few weeks after birth to determine if their thyroid gland has continued to mature.

If screening indicates a potential issue, a Complete Thyroid Panel, which includes thyroid-stimulating hormone (TSH), free and total T3, free and total T4, and reverse T3, should be analyzed using functional medicine ranges to further assess the state of an infant’s thyroid function. Compared to conventional laboratory ranges, which are based on results coming from the overall population, functional medicine ranges are tailored to identify thyroid issues before the onset of more advanced and serious thyroid disease.

TSH is a marker that measures how the pituitary gland is communicating with the thyroid gland. This marker is indicative of hypothyroidism in an infant, child, or adolescent when it is elevated. A TSHwithin the normal range doesn’t rule out thyroid issues by itself since it is an indirect measure of thyroid function.

Free T4 measures the unbound thyroid hormone. When it is decreased, it is a marker of low thyroid function. T4 is converted to T3 in the peripheral tissues. Low levels of T3 can indicate low thyroid function in an infant or an issue with conversion. This can often occur with chronic stress, inflammation, or a high toxic burden.

Some T4 is converted to reverse T3, which competes with T3 (free) for cell receptor sites. Increased levels of reverse T3 can therefore lead to hypothyroidism. This typically reflects a systemic issue like chronic inflammation.

Thyroid antibody testing via thyroid peroxidase (TPO) and anti-thyroglobulin (TG) antibodies are key markers for diagnosing Hashimoto’s disease in infants or the presence of antibodies passed through the placenta from the mother. In addition to elevated TPO antibodies, typically found in Hashimoto’s disease, TG antibodies may also be elevated. However, these antibodies are typically associated with Graves’ disease or autoimmune hyperthyroidism.

Generally, these thyroid hormone levels should be checked every few weeks after starting thyroid hormone medication or after any change in medication dose. As children get older, levels are usually checked every 3-12 months until they have fully grown and puberty is complete. After this time, they should be monitored at least once a year.

Thyroid Supportive Nutrients & Testing

Nutrients such as iodine, iron, tyrosine, zinc, selenium, magnesium, and vitamins such as B2, B3, B6, C, E, and D all contribute to the healthy production of thyroid hormones. Some of these, like selenium and zinc, are also essential for supporting the T4 to T3 conversion. Vitamin A is also important for improving cellular sensitivity to thyroid hormones.

Micronutrient testing examines vitamins, minerals, and other nutrients, as well as the performance and functional deficiencies of these micronutrients.

Iodine can also be measured in the urine. This may be especially useful to confirm either iodine deficiency or excess when infants are born in a location of endemic iodine deficiency or if there’s a history of excess iodine exposure.

Gut Health Testing

Dysbiosis and leaky gut are important factors in the development of autoimmunity, like Hashimoto’s disease. Inflammation can also impact the thyroid. Evaluating gut health can help provide targeted interventions. A Comprehensive Stool Test measures the makeup of the gut microbiome to assess the amounts of healthy and pathogenic gut bacteria, inflammatory markers, intestinal permeability, yeast, and parasites, to assess the status of the gut and guide treatment toward restoring balance.

Especially as children get older, food sensitivities can contribute to increased intestinal permeability (leaky gut), inflammation, and autoimmunity. Foods that someone is sensitive to can be detected with ELISA testing. Additional testing specifically for gluten sensitivity or Celiac disease with the Genova Diagnostics Celiac Profile and the evaluation of the leaky gut marker zonulin can also help to guide treatment.

Genetic and Detoxification Testing

To understand an individual’s genetic risk factors and current detoxification capacity, methylation, detoxification capacity, and glutathione production can be assessed with specialized labs. This can help to detect specific areas to support bringing the body and metabolism back into balance.

Evaluating Environmental Toxins

Everyday objects like plastic toys, pesticides, and other household items can contain chemicals that can disrupt the function of the thyroid. In addition to taking a thorough history to identify exposure to environmental endocrine disrupting chemicals, an environmental toxins screen can quantify exposure to various endocrine-disrupting chemicals.

Additional Labs to Check When Testing for Hypothyroidism in Infants

A physical exam of an infant with hypothyroidism may show decreased muscle tone or a floppy appearance, a hoarse-sounding cry or voice, short arms and legs with wide hands with short fingers, and large soft spots on the skull with widely separated skull bones (widened fontanelles). X-rays of the long bones may also show evidence of growth impairment.

When congenital hypothyroidism is diagnosed, radionuclide scanning (technetium-99m pertechnetate or iodine-123) or ultrasonography can be done to evaluate the size and location of the thyroid gland to distinguish any structural abnormalities like an abnormally developed thyroid gland or a thyroid gland located in the wrong location.

Infants with low free T4 and non-elevated TSH levels on blood testing may have central hypothyroidism due to abnormal pituitary functioning. An MRI of the brain and pituitary can assess for any central nervous system lesions in these children.

Conventional Treatment for Hypothyroidism in Infants

When mild to moderate hypothyroidism is detected and treated early in infants, most impacts can usually be reversed.

Conventional treatment of congenital hypothyroidism usually aims to provide thyroid hormone replacement with medication like levothyroxine (T4 only) that the child’s gland is not producing adequately. Depending on the cause of hypothyroidism, this treatment may be lifelong or transient. Since the neurological and other systems are still in critical developmental periods, thyroid function and treatment in young children is monitored frequently during the first few years of life, as frequently as every 1-2 months during the first six months, every three to four months between age six months and three years, and every six to 12 months from age three years to the end of growth.

Functional Medicine Treatment for Hypothyroidism in Infants

A functional medicine approach to treating hypothyroidism complements thyroid hormone replacement to address identified underlying factors contributing to the imbalance. A personalized treatment approach guided by clinical symptoms and functional lab testing can tailor a nutritional and lifestyle approach that works for each infant and child.

It is imperative to determine the root causes, such as addressing gut imbalances, toxin exposures, systemic inflammation, and chronic high stress, and to avoid any individual triggers. For instance, strategies can be used in Hashimoto’s thyroiditis to rebalance and regulate the immune system rather than only simply replacing thyroid hormone. Utilizing lifestyle and functional medicine treatments to address the root causes can also support the healing of the thyroid gland.

Nutrition or Dietary Considerations for Infants with Hypothyroidism

Some foods and nutritional supplements may interfere with the absorption of thyroid hormone replacement therapy in infants with hypothyroidism. These foods include soy protein formulas, concentrated iron, calcium, aluminum hydroxide, cholestyramine, fiber supplements, and sucralfate. It’s often recommended that thyroid hormone be taken with an empty stomach and at least thirty minutes before feeding when possible to prevent a decrease in medication absorption.

Certain gastrointestinal diseases, such as celiac disease, H. pylori infection, lactose intolerance, inflammatory bowel disease (IBD), and parasitic infections, can also cause malabsorption of thyroid hormone replacement as well as nutrients needed for adequate thyroid hormone production in infants.

Therefore, eliminating factors that can impact thyroid hormone replacement and contribute to immune and hormonal dysfunction is important when dealing with thyroid imbalances in infants and children. Inflammation can negatively impact thyroid function and increases the risk of an autoimmune reaction attacking the thyroid gland. So, a nutrient-rich, anti-inflammatory diet that eliminates individual trigger foods, like gluten or other grains, dairy, processed and refined sugars, and other specific foods that a person is sensitive to helps to calm systemic inflammation.

When infants are breastfeeding, it may be necessary for the mother to follow a similar diet that avoids any foods that the infant is allergic to or sensitive to. Research also suggests that breastfeeding may deliver sufficient thyroid hormones to infants with hypothyroidism to mitigate impacts and prevent impaired neurological development. Breast milk provides a combination of vitamins, proteins, and fats needed for normal growth and development and colostrum, with nutrition and antibodies in the first few days after birth that help improve the infant’s digestive system.

Supplements and Herbs That Are Safe for Infants with Hypothyroidism

In infants and children who show nutrient deficiencies, increasing the intake of micronutrients like vitamin A, zinc, vitamin D, selenium, and omega-3 fatty acids may help to reduce inflammation and prevent hypothyroidism due to nutrient deficiencies. For example, omega-3 fatty acids are essential for thyroid health and brain development and are well tolerated by infants and breastfeeding mothers. Supplementation should be carefully done under the care of a knowledgeable professional.

While iodine is a necessary mineral that the thyroid requires to make thyroid hormones, excessive iodine intake, including from the mother’s breast milk, which can come from excess salt in the form of processed, packaged foods or too much seaweed in the diet, for example, can negatively affect thyroid functioning in the infant. Functional laboratory testing can help guide personalized intake of iodine.

Complementary and Integrative Medicine for Infants with Hypothyroidism

An integrative medicine approach to thyroid disease takes a comprehensive approach to care that addresses all aspects of a person’s body, mind, and spirit. While studies exploring complementary and integrative approaches to hypothyroidism in infants are still needed, integrative medicine approaches in other age ranges have been shown to help with the side effects of medication and treatments, including fatigue, dry mouth, weight gain, and mental “fogginess,” ease stress and anxiety of dealing with a medical condition and help address the symptoms and underlying causes of disease.

Acupuncture

Acupuncture has been explored as a treatment for hypothyroidism in populations ranging from children to older adults, but more specific studies are needed in infants. Traditional Chinese Medicine (TCM) focuses on balancing opposites to stabilize qi (energy), or the essence of life, in order to prevent or undo the excesses or deficiencies in the qi that contribute to disease. In this yin-yang theory, a chronic deficiency of qi or blood negatively impacts the heart, spleen, or kidney contributing to hypothyroidism. Acupuncture involves inserting thin needles at specific acupoints along meridians or energy channels that helps to regulate the flow of qi and address different imbalances. For example, acupressure points along the Yangming meridian have been used in treating various thyroid diseases. Traditional practice and research show that acupuncture can help alleviate clinical symptoms of thyroid disease, such as neck pressure, fatigue, and mood fluctuations, and stimulate the body to rebalance the immune system in cases of autoimmune thyroid disease like Hashimoto’s thyroiditis.

Addressing Environmental Factors

Chemicals found in plastics, pesticides, heavy metals, and other pollutants can disrupt the function of the thyroid. You can reduce your infant’s exposure to these chemicals by using a high-quality water and air filter, choosing organic produce, and avoiding unnecessary plastics.

Summary

Congenital hypothyroidism occurs when an infant is born with an inadequately functioning or absent thyroid gland or when their thyroid hormones cannot act appropriately on peripheral tissues. The symptoms are often subtle due to the trans-placental passage of some maternal thyroid hormones, and the condition is only discovered due to neonatal screening tests for thyroid function. When symptoms occur, they can include decreased activity and increased sleep, feeding difficulty, coarse crying, constipation, and prolonged jaundice or yellowing of the skin and whites of the eyes.

The most common cause of permanent hypothyroidism in infants is thyroid dysgenesis, where the thyroid is missing, ectopic, or severely underdeveloped. Permanent hypothyroidism can also occur due to inborn errors in thyroid hormone biosynthesis (dyshormonogenesis). Secondary central congenital hypothyroidism may occur with a TSH deficiency or congenital hypopituitarism. In other cases, congenital hypothyroidism is transient from anti-thyroid antibodies or medications that cross the placenta from the mother or in infants born in areas of endemic iodine deficiency.

The diagnosis of hypothyroidism in infants is confirmed by finding elevated serum TSH and low T4 or free T4 levels on blood testing. Further testing for nutrient deficiencies, gut imbalances, detoxification capacity, thyroid radionuclide uptake and scan, thyroid ultrasonography, or thyroid antibodies may help pinpoint the underlying contributing factors.

A functional medicine approach to hypothyroidism in infants can supplement conventional thyroid hormone replacement by uncovering and addressing contributing factors. Early identification and treatment of the root causes of hypothyroidism can allow an infant to achieve normal growth and development.