Congenital Hypothyroidism

Congenital hypothyroidism means that a baby is born with too little thyroid hormone in the body. The thyroid is a small gland in the neck that controls growth, brain development, and metabolism. When the thyroid hormone is low at birth and is not treated quickly, it can lead to slow growth and permanent problems in learning and thinking. Because early treatment can prevent these problems, most countries screen all newborn babies for this condition using a heel-prick blood test in the first days of life.NCBI+1

In congenital hypothyroidism, the problem can be in the thyroid gland itself, or in the brain areas (pituitary or hypothalamus) that control the thyroid. Doctors call this whole group of disorders “congenital hypothyroidism,” but they also divide it into “primary” (problem in the thyroid), “central” (problem in pituitary or hypothalamus), or more rare forms where the body cannot use thyroid hormone properly.Frontiers+1

Other names

Doctors may use several other names for congenital hypothyroidism. They may call it “CH” for short. They often say “primary congenital hypothyroidism” when the problem is in the baby’s thyroid gland, and “central congenital hypothyroidism” when the problem is in the pituitary or hypothalamus. Older books sometimes use the word “cretinism” for severe, untreated congenital hypothyroidism that causes serious growth and brain problems, but this word is now avoided because it is hurtful and not respectful.Wikipedia+1

You may also see the terms “neonatal hypothyroidism” and “thyroid hormone deficiency present at birth.” These phrases all describe the same basic idea: the baby does not have enough thyroid hormone in the first weeks of life, when the brain and body are growing very quickly and need this hormone to develop in a healthy way.NCBI+1

Types

There are several main types of congenital hypothyroidism. Doctors group them by where the problem starts and by how long it lasts.

One major group is primary congenital hypothyroidism due to thyroid dysgenesis. “Dysgenesis” means the thyroid gland did not form normally in the womb. The gland may be completely absent (agenesis), very small (hypoplasia), or in the wrong place (ectopic thyroid, such as a “lingual thyroid” at the back of the tongue). This group is the most common cause of permanent congenital hypothyroidism in areas with enough iodine.ETJ+1

Another group is primary congenital hypothyroidism due to dyshormonogenesis. In this type, the thyroid gland is present and usually in the right place, but it cannot make thyroid hormone normally because one of the steps in hormone production is faulty. This problem is often genetic and can run in families. Over time, the gland may become enlarged and form a goiter because it is working hard but still not making enough hormone.PMC+1

A further group is central congenital hypothyroidism. Here the thyroid gland may be normal, but the brain does not send the right signals to it. The hypothalamus or pituitary gland may not produce enough TSH (thyroid-stimulating hormone), or may not respond properly. This type is less common and is often seen together with other pituitary hormone problems.Frontiers+1

There is also transient congenital hypothyroidism, in which the thyroid hormone levels are low for some weeks or months after birth but later become normal without lifelong treatment. This can happen, for example, if the mother had certain thyroid-blocking antibodies, took antithyroid medicines, or if the baby was exposed to too much or too little iodine around birth.J-STAGE+1

Very rarely, peripheral congenital hypothyroidism occurs when the thyroid hormone is made in normal amounts but the body tissues do not respond properly. This can happen in conditions like thyroid hormone resistance or certain defects in hormone transport and is usually caused by genetic changes.Wiley Online Library+1

Causes

1. Thyroid agenesis (no thyroid gland)
   In some babies, the thyroid gland simply does not form at all during pregnancy. This is called agenesis. Because there is no thyroid tissue, almost no thyroid hormone is made. The exact reason is often unknown, though a small number of cases are linked to gene changes that affect thyroid development.ETJ+1

2. Thyroid ectopy (gland in the wrong place)
   Sometimes the thyroid gland forms but does not move to its normal position in the lower neck. It may stay high in the neck or at the base of the tongue (lingual thyroid). These abnormal positions can limit how well the gland works and may reduce hormone production, leading to congenital hypothyroidism.Wikipedia+1

3. Thyroid hypoplasia (small thyroid gland)
   In thyroid hypoplasia, the gland is in the right place but is smaller than usual. The small amount of thyroid tissue cannot produce enough hormone for the baby’s needs. This condition is one form of thyroid dysgenesis and often causes permanent congenital hypothyroidism.Caspian Journal of Internal Medicine+1

4. Thyroid dyshormonogenesis (hormone-making defect)
   Dyshormonogenesis means the steps used to build thyroid hormone inside the gland do not work normally. Examples include problems with iodine transport, organification (attaching iodine), or making thyroglobulin. The gland may become enlarged (goiter), but hormone levels remain low. This cause is often inherited and can be seen in more than one family member.PMC+1

5. Genetic mutations in thyroid development genes (PAX8, TSHR, others)
   Certain genes guide the formation and positioning of the thyroid. Mutations in genes like PAX8 and TSHR can stop the gland from growing normally or responding to TSH, leading to thyroid dysgenesis or poor hormone production. Only a small portion of cases are clearly inherited in this way, but genetics is an important factor in some families.Wiley Online Library+1

6. Central hypothyroidism due to pituitary defects
   If the pituitary gland does not make enough TSH, the thyroid is not properly “told” to produce hormone. Babies with pituitary defects may have low TSH and low thyroid hormone levels, plus other hormone problems such as low cortisol or growth hormone. This leads to central congenital hypothyroidism and needs careful hormone replacement.Frontiers+1

7. Central hypothyroidism due to hypothalamic defects
   The hypothalamus makes TRH, a hormone that tells the pituitary to release TSH. If TRH is low due to structural or genetic problems in the hypothalamus, the pituitary may not release enough TSH. As a result, the thyroid produces too little hormone even though the gland itself might be normal.Frontiers+1

8. Iodine deficiency in the mother and baby
   Iodine is a building block of thyroid hormone. In many low-iodine areas of the world, the most common cause of congenital hypothyroidism is not enough iodine in the mother’s diet and, therefore, in the baby. Without adequate iodine, the baby’s thyroid cannot make enough hormone, which can harm growth and brain development.Wikipedia+1

9. Excess iodine exposure in the newborn
   Too much iodine can also temporarily block the thyroid, especially in very young babies. This can happen if large amounts of iodine-containing antiseptics (like povidone-iodine) or contrast dyes are used around the time of birth. The thyroid “shuts down” for a while, causing transient congenital hypothyroidism.J-STAGE+1

10. Maternal antithyroid drugs during pregnancy
    If a pregnant person takes antithyroid medicines (such as methimazole or propylthiouracil) to treat an overactive thyroid, these drugs can cross the placenta and reach the baby. In some cases, they may reduce the baby’s thyroid hormone production, leading to transient hypothyroidism in the newborn.Liebert Publishing+1

11. Maternal TSH receptor-blocking antibodies
    People with autoimmune thyroid disease can produce antibodies that block the TSH receptor. These antibodies can cross the placenta and attach to the baby’s thyroid, preventing TSH from stimulating hormone production. The result is low thyroid hormone levels in the newborn, sometimes lasting several months until the antibodies disappear.J-STAGE+1

12. Maternal radioactive iodine treatment before or during pregnancy
    If radioactive iodine is used to treat thyroid disease in the mother before pregnancy and the thyroid is destroyed, or if it is used unintentionally in early pregnancy, it can affect the fetus. In some cases, radiation exposure damages the developing fetal thyroid, leading to congenital hypothyroidism.Liebert Publishing+1

13. Maternal severe untreated hypothyroidism
    If the pregnant person’s own thyroid hormone levels are very low and not treated, the fetus may receive too little thyroid hormone across the placenta. While maternal hormone supply partially protects the fetus, severe and prolonged maternal hypothyroidism can still harm fetal brain development and may also be associated with congenital hypothyroidism in the baby.Liebert Publishing+1

14. Prematurity and very low birth weight
    Babies born very early or very small often have immature thyroid function. They may show low thyroid hormone levels (hypothyroxinemia), sometimes with delayed TSH rise. In some of these infants, the low levels are temporary, but others may have true congenital hypothyroidism that becomes clear on repeat testing.ETJ+1

15. Chromosomal and syndromic disorders
    Certain genetic syndromes and chromosomal problems, such as Down syndrome, are more often seen together with congenital hypothyroidism. In these conditions, abnormal development of many organs, including the thyroid or brain centers, can lead to low thyroid hormone levels from birth.Frontiers+1

16. Mutations affecting thyroid hormone transport or action
    In rare cases, gene changes affect the way thyroid hormone enters cells or binds to its receptor inside the cell. Even if hormone levels in the blood are normal or high, the tissues cannot respond properly. This “peripheral” resistance can present like hypothyroidism at birth.Wiley Online Library+1

17. Maternal environmental toxins and endocrine disruptors
    Exposure to certain environmental chemicals, such as organochlorine pesticides or dioxin-like compounds, has been linked in some studies to a higher risk of congenital hypothyroidism. These substances may interfere with thyroid hormone production or action in the fetus, although the exact mechanisms are still being studied.Wikipedia+1

18. Thyroid hormone synthesis defects from gene mutations (e.g., TPO, TG)
    Specific gene mutations, such as in thyroid peroxidase (TPO) or thyroglobulin (TG), can block key steps in hormone production. Babies with these defects often have a large thyroid (goiter) but low hormone levels. These inherited forms of dyshormonogenesis often cause lifelong congenital hypothyroidism.PMC+1

19. TSH receptor defects (TSHR mutations)
    Sometimes the TSH receptor itself is abnormal because of gene changes. Even if the pituitary makes normal or high TSH, the thyroid cannot “hear” the signal and does not respond properly. This leads to low thyroid hormone production from birth and is another genetic cause of congenital hypothyroidism.Wiley Online Library+1

20. Defects of thyroid embryonic migration or survival (complex genetic patterns)
    Recent research shows that thyroid dysgenesis often arises from combined genetic factors affecting cell survival, differentiation, and migration during early fetal life. These subtle changes can lead to partial or total absence of thyroid tissue or ectopic thyroid tissue, and therefore to primary congenital hypothyroidism.MDPI+1

Symptoms

Many babies with congenital hypothyroidism look normal at birth and have no clear symptoms. This is why newborn screening is so important. When symptoms do appear, they are often mild at first and become clearer over time if the condition is not treated.

1. Excessive sleepiness
   Babies with congenital hypothyroidism may sleep much more than usual and be difficult to wake for feeds. They may seem “too quiet” or less active than other babies, which caregivers may mistake for a calm personality rather than a health problem.NCBI+1

2. Poor feeding and low interest in sucking
   The baby may not suck strongly or may lose interest in feeding quickly. This can lead to poor weight gain and dehydration. Because many newborns have some feeding difficulties, this early sign can be easy to miss without screening.NCBI+1

3. Low muscle tone (floppiness)
   The baby’s muscles may feel soft and floppy. When you pick up the baby, the head may lag behind, and the limbs may hang loosely. This low muscle tone, called hypotonia, is a common sign of congenital hypothyroidism when it is more severe or untreated.NCBI+1

4. Low or hoarse cry
   Some affected babies have a quiet, low-pitched, or hoarse cry. This may reflect swelling of the vocal cords or overall decreased muscle tone and is one of the classic signs doctors look for during physical examination.NCBI+1

5. Constipation
   Slow bowel movements are common in hypothyroidism. Babies may pass stool less often and may strain more. Long-lasting constipation in a newborn, especially together with other signs, can raise suspicion for congenital hypothyroidism.NCBI+1

6. Prolonged jaundice
   Many newborns have some yellowing of the skin (jaundice) for a few days. In congenital hypothyroidism, jaundice often lasts longer than usual. The baby may stay yellow for several weeks because the liver clears bilirubin more slowly when thyroid hormone is low.Bangladesh Journals Online+1

7. Low body temperature (feeling cold)
   Babies with low thyroid hormone may have a lower-than-normal body temperature. They may feel cool to the touch, and their hands and feet may be cold. This happens because thyroid hormone helps control how the body makes and uses heat.NCBI+1

8. Puffy face and swollen eyelids
   A puffy face and swollen eyelids are common signs in more severe congenital hypothyroidism. This “myxedematous” appearance comes from extra fluid and thickening of tissues under the skin, which are linked to low thyroid hormone levels.Wikipedia+1

9. Large tongue (macroglossia)
   Some babies have a tongue that looks large and may stick out of the mouth. This can interfere with feeding and breathing in severe cases. The large tongue is another classic sign of untreated congenital hypothyroidism.Wikipedia+1

10. Umbilical hernia
    The baby’s belly button may bulge out, especially when crying. This is called an umbilical hernia. It occurs more often in babies with congenital hypothyroidism and is related to weak abdominal muscles and increased pressure inside the belly.Wikipedia+1

11. Large soft spots on the skull (fontanelles)
    The soft areas on a baby’s head, especially the front fontanelle, may be larger and may close later than usual. A persistent posterior fontanelle at the back of the head can also be a sign of hypothyroidism in infants.Wikipedia+1

12. Dry, cool, or mottled skin
    The skin may feel dry and cool and can look pale or mottled (patchy). Hair may be dry or sparse. These skin changes reflect slow metabolism and poor circulation caused by low thyroid hormone levels.NCBI+1

13. Slow heart rate
    A baby with congenital hypothyroidism may have a lower-than-normal heart rate. Doctors often pick this up when listening to the heart or using a monitor. Thyroid hormone normally helps keep the heart beating at a healthy speed, so low levels can slow the rate.NCBI+1

14. Poor growth (slow weight and length gain)
    Over time, untreated congenital hypothyroidism leads to slow growth in both weight and length. The baby may drop down on the growth chart compared with other children of the same age and sex. Early diagnosis and treatment usually prevent this problem.NCBI+1

15. Delayed development and learning problems (if untreated)
    If congenital hypothyroidism is not found and treated early, the child can develop delays in sitting, walking, talking, and thinking. In severe untreated cases, permanent intellectual disability can occur. Newborn screening is designed to prevent this outcome by starting treatment in the first weeks of life.Bangladesh Journals Online+1

Diagnostic tests

Doctors use a mix of physical examination, simple bedside checks, blood tests, and imaging studies to diagnose congenital hypothyroidism. The key is to confirm low thyroid hormone levels and understand the cause so treatment can start quickly and be tailored to the child’s needs.NCBI+1

Physical exam tests

1. General newborn physical exam
   The doctor carefully looks at the baby’s overall appearance, breathing, color, and activity. They check for signs like puffy face, large tongue, umbilical hernia, and low muscle tone. This exam helps identify babies who may have congenital hypothyroidism, although many affected babies look normal in the first days.NCBI+1

2. Growth and head circumference measurement
   The baby’s weight, length, and head size are plotted on growth charts. Babies with untreated congenital hypothyroidism may show slow growth or a head that is too large or too small compared with the body. Regular measurements help track the effect of treatment over time.analesdepediatria.org+1

3. Neurologic exam and reflex check
   The doctor checks muscle tone, posture, and newborn reflexes such as the Moro reflex. Low muscle tone and sluggish reflexes can be signs of hypothyroidism. Over time, treatment with thyroid hormone usually normalizes these findings.NCBI+1

4. Skin and jaundice assessment
   The skin is examined for dryness, mottling, and prolonged jaundice. Long-lasting yellow skin, especially beyond the first couple of weeks, may suggest congenital hypothyroidism when seen together with other signs.Bangladesh Journals Online+1

Manual tests (simple bedside maneuvers)

5. Palpation of the thyroid gland in the neck
   The doctor gently feels the baby’s neck to check whether the thyroid gland can be felt and whether it is enlarged, normal, or absent. In many babies with thyroid dysgenesis, the gland cannot be felt at all. In dyshormonogenesis, the gland may be enlarged into a goiter.NCBI+1

6. Abdominal exam for umbilical hernia
   By pressing gently around the belly button, the doctor can feel if there is a hernia. An umbilical hernia is not specific to congenital hypothyroidism, but it is common in more severe cases and therefore supports the diagnosis when other signs are present.Wikipedia+1

7. Muscle tone and joint movement test
   The doctor moves the baby’s arms and legs and gently pulls the baby to a sitting position to see how much the head lags. Low resistance and marked head lag suggest reduced muscle tone, which is a common feature of hypothyroidism in infants.NCBI+1

8. Simple vision and eye-movement check
   The clinician may observe whether the baby can briefly fix on a face or light and whether the eyes move together smoothly. While this is not a specific test for hypothyroidism, delayed visual tracking can be one sign of slower brain development when the condition is not treated early.analesdepediatria.org+1

Lab and pathological tests

9. Newborn screening heel-prick TSH and/or T4 test
   This is the most important initial test. A few drops of blood from the baby’s heel are placed on a card and tested in the lab. Most programs measure TSH, sometimes with T4. High TSH and low T4 suggest primary congenital hypothyroidism. This screening has dramatically reduced the number of children with permanent intellectual disability from this condition.ETJ+1

10. Confirmatory serum TSH test
    If the screening test is abnormal, blood is taken from a vein to measure TSH directly. A high TSH level confirms that the pituitary is trying to stimulate the thyroid, which is typical of primary congenital hypothyroidism. Low or inappropriately normal TSH with low T4 suggests central hypothyroidism.American Thyroid Association+1

11. Confirmatory serum free T4 and total T4 test
    Free T4 shows the active thyroid hormone in the blood. Low free T4 supports the diagnosis of hypothyroidism. Together with TSH, this test helps doctors decide how urgent treatment is and whether the problem is mild, moderate, or severe.American Thyroid Association+1

12. Serum thyroglobulin level
    Thyroglobulin is a protein made by thyroid cells. If thyroglobulin is very low or absent in a baby with high TSH and low T4, it may suggest that there is little or no thyroid tissue (agenesis). Normal or high thyroglobulin suggests that thyroid tissue is present, as in ectopy or dyshormonogenesis.PMC+1

13. Thyroid autoantibody tests (including TSH receptor antibodies)
    Testing for thyroid antibodies in the baby (and sometimes the mother) can identify immune causes of congenital hypothyroidism. TSH receptor–blocking antibodies are especially important, as they can pass from mother to fetus and block the baby’s thyroid function temporarily.J-STAGE+1

14. Pituitary hormone panel (cortisol, growth hormone, others)
    If central hypothyroidism is suspected, the doctor may test other pituitary-dependent hormones, such as cortisol, growth hormone, and gonadotropins. Low levels in several hormones suggest a broader pituitary problem, which needs careful management and often brain imaging.Frontiers+1

15. Genetic testing for congenital hypothyroidism genes
    In selected cases, especially when there is a family history or unusual features, genetic testing may be done. It looks for changes in genes involved in thyroid development or hormone production, such as PAX8, TSHR, TPO, TG, and others. This can clarify the cause, guide family counseling, and sometimes predict whether hypothyroidism is permanent.Wiley Online Library+1

Electrodiagnostic tests

16. Electrocardiogram (ECG)
    An ECG records the electrical activity of the heart. In congenital hypothyroidism, the heart rate may be slow, and certain electrical patterns can reflect the effects of low thyroid hormone on the heart. While not a primary diagnostic test, ECG can help assess overall health and the impact of the condition on the baby’s heart.NCBI+1

17. Brainstem auditory evoked response (BAER) / hearing test
    Hearing tests using automatic brainstem response techniques check how the inner ear and brainstem respond to sound. Babies with congenital hypothyroidism may have a higher risk of hearing problems. Early detection of hearing loss allows prompt support and can improve language and learning outcomes.PubMed+1

Imaging tests

18. Thyroid ultrasound
    Ultrasound uses sound waves to create pictures of the thyroid. It helps show whether the gland is present, where it is located, and how big it is. Ultrasound is painless and is often used together with nuclear scans to distinguish between agenesis, ectopy, and dyshormonogenesis.NCBI+1

19. Thyroid radionuclide scan (scintigraphy)
    In a thyroid scan, a tiny amount of radioactive material (often technetium-99m or iodine-123) is given, and a special camera shows how the thyroid takes it up. This test helps locate the thyroid (for example, in the tongue or high in the neck) and can show whether it is functioning. It is very useful for classifying the cause of congenital hypothyroidism.PMC+1

20. Bone age X-ray (usually of the knee or wrist)
    An X-ray of certain bones, such as the knee at birth or the wrist later, can show how mature the skeleton is. In significant congenital hypothyroidism, bone development is often delayed. This test helps estimate how long the thyroid hormone has been low and may give clues about the severity and timing of the condition.analesdepediatria.org+1

Non-pharmacological treatments for congenital hypothyroidism

1. Early newborn screening and diagnosis
   Newborn blood-spot screening (heel-prick test) is the most important non-drug intervention for congenital hypothyroidism. It allows doctors to pick up low thyroid hormone levels in the first days of life, before symptoms appear. Early diagnosis and quick start of treatment protect the baby’s brain and help them reach normal intelligence and growth in later childhood.AAP Publications+1

2. Rapid start of thyroid hormone replacement
   Once congenital hypothyroidism is confirmed, starting levothyroxine as soon as possible—ideally within the first 2 weeks of life—is a key “treatment step,” even though the medicine itself is pharmacological. The non-drug part is organizing urgent evaluation, pharmacy access, and parent teaching so the first dose is not delayed. Early initiation greatly improves cognitive and motor outcomes.Brieflands+1

3. Parent and caregiver education
   Parents need clear teaching about the disease, the importance of daily medication, how to give the dose, and why follow-up blood tests matter. Simple language, written material, and repeated teaching help families stay consistent. Better understanding has been linked to more regular dosing and better thyroid hormone control, which supports normal brain and body development.American Thyroid Association+1

4. Correct administration technique
   For infants, levothyroxine tablets are usually crushed and mixed with a small amount of breast milk, formula, or water, then given by spoon or syringe. Caregivers are taught not to mix the dose with soy formula, iron drops, or high-fiber cereal, which can reduce absorption. Good administration technique is a practical, non-drug step that helps keep hormone levels stable.American Thyroid Association+1

5. Regular blood test monitoring
   Thyroid-stimulating hormone (TSH) and free T4 tests are checked frequently in the first months, then at wider intervals as the child grows. The “treatment” here is the careful schedule of lab visits and clinic appointments, which lets the team adjust the levothyroxine dose to keep levels in the target range and prevent under- or over-treatment.Medscape+1

6. Growth and development tracking
   At each visit, height, weight, and head size are plotted on growth charts, and milestones like rolling, sitting, walking, and talking are checked. This ongoing developmental surveillance is a non-drug strategy to catch any delays early. If issues are found, the child can be referred quickly for therapy services and more detailed assessment.PMC+1

7. Early intervention developmental programs
   Some babies with congenital hypothyroidism benefit from early intervention services such as home-based developmental programs. These programs use structured play, movement, and communication activities to support the child’s brain development and learning. Starting early helps reinforce the positive effects of hormone replacement on cognition and motor skills.PMC+1

8. Physical therapy
   If a child has low muscle tone, delayed sitting or walking, or clumsiness, a physical therapist can design exercises and play-based activities to build strength, balance, and coordination. This therapy works alongside hormone treatment and is especially helpful when congenital hypothyroidism was severe or treatment started late.PMC+1

9. Occupational therapy
   Occupational therapists help with fine motor skills, feeding, self-care, and sensory processing. In congenital hypothyroidism, they may work on hand-eye coordination, grasping toys, or using a spoon. They also teach parents how to support these skills at home, improving independence and participation in daily activities.PMC+1

10. Speech and language therapy
    Some children, especially those diagnosed late or with more severe hormone deficiency, may have slower language development. Speech-language therapists use games and structured communication tasks to boost understanding and speaking. This non-drug therapy complements the biological effects of thyroid hormone on brain development.PMC+1

11. Hearing screening and follow-up
    Babies with congenital hypothyroidism can have hearing problems, which may further affect language and school performance. Routine newborn hearing screening and repeat tests if there are concerns allow early fitting of hearing aids or other support. Protecting hearing adds another layer of support for good long-term outcomes.PMC+1

12. Vision and eye assessments
    Vision checks are part of standard pediatric care but are especially important if congenital hypothyroidism was severe or associated with other congenital anomalies. Detecting and treating vision problems early improves learning and interaction with the environment, strengthening the benefits of correct hormone replacement.PMC+1

13. Psychosocial and family support
    Chronic conditions in a baby can be stressful for families. Counseling, parent support groups, and social work input help families manage anxiety, practical challenges, and emotional strain. When parents are supported, they are more likely to adhere to follow-up plans and give medication correctly, which protects the child’s health.ETJ+1

14. School-age educational support
    Most children treated early grow and learn normally, but some may still need extra help at school, such as tutoring, individualized education plans, or classroom adjustments. Close communication between parents, teachers, and healthcare providers allows early educational support if attention, learning, or memory problems appear.PMC+1

15. Avoiding interfering foods around dosing time
    Families are taught to avoid giving levothyroxine at the same time as soy formula, iron supplements, calcium-rich products, or large amounts of fiber, because these can reduce absorption. The non-drug strategy is careful daily planning of meals and medicine times so the hormone works properly.PMC+1

16. Coordination of care by a pediatric endocrinology team
    Having a clear treatment plan led by a pediatric endocrinologist, with nurses, dietitians, and therapists, helps avoid missed visits, duplicate tests, or conflicting advice. This coordinated care model is a powerful non-pharmacological tool to keep congenital hypothyroidism well controlled through childhood and adolescence.ScienceDirect+1

17. Preconception and pregnancy counseling for mothers
    Women with known thyroid disease or a history of a child with congenital hypothyroidism can benefit from counseling before and during pregnancy. Optimizing maternal thyroid status and iodine intake reduces the risk of fetal thyroid problems and supports healthy brain development in future pregnancies.American Thyroid Association+1

18. Iodine sufficiency at population level
    Public health strategies such as iodized salt programs help ensure that pregnant women get enough iodine, which the fetus needs to make thyroid hormone. These measures reduce the risk of fetal and neonatal hypothyroidism in areas with natural iodine deficiency.IAEA Publications+1

19. Transition planning for adolescence
    As the child with congenital hypothyroidism becomes a teenager, doctors gradually teach them to take responsibility for their medication and appointments. Structured transition planning prepares them to move from pediatric to adult endocrine care while maintaining good control of thyroid function.ScienceDirect+1

20. Health-literacy-friendly communication
    Using simple language, visual aids, and culturally appropriate materials improves understanding in families with lower health literacy. Regulatory reviews for levothyroxine patient leaflets also emphasize clear, easy-to-read wording, which supports safer long-term use.FDA Access Data+1

Drug treatments for congenital hypothyroidism

Important: Only a doctor should choose the specific product, dose, and schedule. The information below is general and not a dosing guide.

Evidence shows that levothyroxine (synthetic T4) is the standard and almost always the only required drug treatment for congenital hypothyroidism. Different FDA-approved brands and formulations exist; their labels clearly state indications for congenital or acquired hypothyroidism.FDA Access Data+2FDA Access Data+2

1. Levothyroxine sodium tablets (generic)
   Generic levothyroxine tablets are widely used and FDA-approved for replacement therapy in primary, secondary, and tertiary congenital or acquired hypothyroidism in neonates, children, and adults. The drug is a synthetic form of T4, identical to the hormone made by the thyroid gland. Dosing is weight-based and adjusted using TSH and free T4 tests. Over-dosing can cause fast heart rate, irritability, poor sleep, and bone effects; under-dosing leaves the child hypothyroid.FDA Access Data+2FDA Access Data+2

2. Synthroid (levothyroxine sodium tablets)
   Synthroid is a branded levothyroxine tablet with labeling that specifically includes congenital hypothyroidism. It is given once daily, ideally on an empty stomach. The purpose is to normalize thyroid hormone levels and TSH to support normal brain and body growth. Side effects are usually those of too much or too little thyroid hormone, such as palpitations, weight changes, or behavior changes, and require dose adjustment by the physician.FDA Access Data+2FDA Access Data+2

3. LEVO-T (levothyroxine sodium tablets)
   LEVO-T is another FDA-approved levothyroxine tablet product indicated as replacement therapy in congenital and acquired hypothyroidism. It works by providing stable T4 hormone, which the body converts to active T3 in tissues. The tablet is usually crushed for infants. Like other levothyroxine products, it must not be used for weight loss and should be monitored with regular thyroid tests.FDA Access Data+1

4. Unithroid (levothyroxine sodium tablets, USP)
   Unithroid is a levothyroxine tablet brand with dosing guidelines for pediatric hypothyroidism in its label. The purpose is long-term replacement of missing thyroid hormone. The mechanism is the same as endogenous T4: it enters cells, is converted to T3, and binds nuclear receptors that regulate metabolism and brain development. Adverse effects reflect overtreatment or undertreatment and are managed by adjusting dose rather than stopping therapy.FDA Access Data+1

5. Tirosint (levothyroxine sodium capsules)
   Tirosint is a soft-gel capsule formulation of levothyroxine with few excipients, helpful in patients with allergies, malabsorption, or intolerance to tablet fillers. It is indicated for hypothyroidism, including congenital forms. The capsule delivers T4 through the gut into the bloodstream. Side effects are similar to other levothyroxine products; capsules must be swallowed intact and are not usually used for very small infants who cannot swallow them.FDA Access Data+1

6. Tirosint-SOL (levothyroxine sodium oral solution)
   Tirosint-SOL is an oral solution of levothyroxine supplied in single-dose ampoules, approved for hypothyroidism including congenital causes. This liquid form can be easier to give accurately in babies and children who cannot swallow tablets. Its mechanism and purpose are identical to tablet forms: stable T4 replacement. Labels warn against using thyroid hormones for weight loss and emphasize careful dosing and monitoring to avoid cardiac and bone side effects.FDA Access Data+2FDA Access Data+2

7. Thyquidity (levothyroxine sodium oral solution)
   Thyquidity is another FDA-approved levothyroxine oral solution. It provides a measured dose of T4 in liquid form, useful in pediatric patients. Regulatory reviews highlight the need for caution in neonates due to excipients such as glycerol, so doctors balance benefits and potential risks when choosing this product. The purpose remains restoration of normal thyroid hormone levels, with side effects mainly from over- or under-replacement.FDA Access Data+1

8. Levothyroxine sodium injection (hospital use)
   In rare situations where the baby or child cannot take oral medicines (for example, severe illness, gut surgery), an injectable levothyroxine product may be used in hospital to maintain thyroid hormone levels. This short-term bridge mimics oral therapy but is carefully monitored due to the risk of rapid hormone shifts. Once the child can feed, doctors switch back to oral levothyroxine.FDA Access Data+1

9. Liothyronine (T3) – limited and special-case use
   Liothyronine is synthetic T3. Historic regimens sometimes used T3 with T4, but modern guidelines do not recommend routine T3 use in congenital hypothyroidism because T4 alone is effective and safer for the developing brain. T3 may be considered only in rare, specialized scenarios by experts. Side effects, especially heart rhythm changes, are more likely if overdosed.JAMA Network+1

10. Iodine solution or iodide (for specific deficiency situations)
    In areas with true iodine deficiency, iodized salt and, occasionally, medical iodine supplements for pregnant women can help prevent fetal and neonatal hypothyroidism. However, routine iodine drops for infants with congenital hypothyroidism are not standard, especially once they are on levothyroxine. Excess iodine can worsen thyroid dysfunction, so any iodine drug or supplement must be prescribed carefully by a doctor.IAEA Publications+2MDPI+2

There are not 20 different disease-specific drugs for congenital hypothyroidism. High-quality guidelines agree that levothyroxine monotherapy is the key and usually only necessary drug treatment, with dosing and formulation individualized to the child.Medscape+2ScienceDirect+2

Dietary molecular supplements

Any supplement should be discussed with the child’s endocrinologist to avoid interactions or excess intake.

1. Iodine (from iodized salt and food)
   Iodine is a trace element needed to make thyroid hormone. For congenital hypothyroidism already treated with levothyroxine, the goal is simply normal dietary iodine, not extra high doses. Adequate iodine in the mother during pregnancy and breastfeeding supports fetal and infant brain development, but too much iodine can disturb thyroid function, so supplementation must follow medical advice.IAEA Publications+1

2. Selenium
   Selenium is a cofactor for enzymes that convert T4 to active T3 and help protect the thyroid from oxidative stress. Some studies suggest that adequate selenium intake supports overall thyroid health, though it does not replace levothyroxine in congenital hypothyroidism. Standard dietary amounts from foods or age-appropriate multivitamins are usually sufficient; high-dose supplements can cause hair and nail problems or stomach upset.PMC

3. Iron
   Iron deficiency anemia can impair growth and may interact with levothyroxine absorption if iron drops are given at the same time as the hormone. Ensuring good iron intake through food (meat, beans, leafy greens) or prescribed supplements supports healthy blood and energy levels. If iron is needed, doctors usually separate it from levothyroxine dosing by several hours to avoid reduced hormone absorption.PMC+1

4. Zinc
   Zinc plays a role in growth, immune function, and many enzymes, including some involved in thyroid hormone metabolism. A balanced diet usually supplies enough zinc, but in cases of documented deficiency, a supplement may be recommended. Excess zinc can interfere with copper balance and cause gastrointestinal symptoms, so medical supervision is important.PMC

5. Vitamin D
   Vitamin D supports bone health and immune function. Children with chronic illnesses or limited sun exposure sometimes have low vitamin D levels. If tests confirm deficiency, doctors may prescribe drops or tablets. Correcting vitamin D deficiency helps protect bones, which is important because both under- and over-treatment with thyroid hormone can affect bone density over time.ScienceDirect+1

6. Omega-3 fatty acids
   Omega-3 fats from fish, flax, or supplements may support brain and eye development. While they do not treat congenital hypothyroidism, they can be part of an overall healthy diet for the child. If fish-oil or algal-oil supplements are used, dosing should match pediatric recommendations to avoid stomach upset or excess vitamin A or D from certain products.PMC+1

7. Tyrosine (amino acid)
   Tyrosine is the amino acid backbone used to build thyroid hormones in the normal gland. In congenital hypothyroidism treated with levothyroxine, the body receives ready-made T4, so extra tyrosine is not usually necessary. Adequate protein in the diet gives enough tyrosine. High-dose supplements in children are not standard and should only be considered under specialist guidance.PMC

8. Multivitamin with trace elements
   A standard pediatric multivitamin that includes appropriate amounts of iodine, selenium, zinc, and other micronutrients can support general health in a child with congenital hypothyroidism, especially if diet is limited. It must not replace thyroid hormone replacement and should avoid very high iodine doses. Parents should tell the doctor about any multivitamin so interactions with levothyroxine timing can be planned.PMC+1

9. Probiotics
   Probiotics support gut health and may improve digestion and stool patterns. They do not directly affect thyroid hormone levels but can help overall well-being, especially in children with feeding difficulties or frequent antibiotics. Evidence in congenital hypothyroidism is limited, so probiotics should be seen as optional supportive care rather than core therapy.ScienceDirect

10. Choline and other brain-support nutrients
    Choline, along with omega-3 fatty acids and other nutrients, plays a role in brain development and cell membranes. Some formulas and fortified foods contain extra choline. For babies treated properly with levothyroxine, usual dietary intake is generally enough. Extra “brain booster” supplements are not proven to fix developmental delays and should not replace early therapy or developmental interventions.PMC+1

Immunity-booster, regenerative, and stem-cell-related drugs

At present, there are no approved stem-cell or regenerative drugs specifically for congenital hypothyroidism. Research is exploring thyroid tissue grown from stem cells and thyroid organoids, but this is experimental and not available as routine treatment.ETJ+1

1. Routine childhood vaccines
   Vaccination does not “boost” the immune system in a vague way, but it protects children with congenital hypothyroidism from infections like measles, whooping cough, and pneumonia. Preventing serious infections helps avoid hospitalizations that might interrupt levothyroxine dosing and growth. Vaccines are given following national schedules, in the same way as for other children.AAP Publications+1

2. Good nutritional support
   A diet with enough calories, protein, vitamins, and minerals helps the immune system work well. While not a drug, nutrition is a biological support for tissue repair and resistance to infection. In children with congenital hypothyroidism, good nutrition works together with hormone therapy to support growth and resilience.PMC+1

3. Experimental stem-cell thyroid tissue research
   Laboratory studies are developing thyroid cells from pluripotent stem cells and forming “mini-thyroid” organoids. The aim is that, in the future, such tissues might replace damaged thyroid function. For now, this work is in pre-clinical or early research stages and is not used in clinical care for babies or children.ETJ+1

4. Regenerative medicine for associated conditions
   Some children with congenital hypothyroidism have other congenital issues (for example, heart defects). In those fields, regenerative therapies—such as tissue-engineered heart valves—are being studied. These are directed at the associated organ problems, not at the thyroid itself. They remain experimental and are managed in specialist centers.ETJ+1

5. Growth hormone therapy (only if another deficiency is present)
   Growth hormone is not a treatment for congenital hypothyroidism, but in rare cases where a child also has growth hormone deficiency, doctors may use growth hormone injections once the thyroid status is well controlled. The aim is to normalize height, not to regenerate thyroid tissue. This decision is made by pediatric endocrinology specialists after detailed testing.ScienceDirect

6. Future gene or cell-based therapies (theoretical)
   Scientists have proposed that, many years in the future, gene therapy or cell-based approaches could correct certain genetic forms of thyroid dysgenesis or dyshormonogenesis. At present, this remains theoretical, with no approved products. Until then, levothyroxine replacement remains the safe, effective, and evidence-based standard of care.ETJ+1

Surgeries related to congenital hypothyroidism

Surgery is not a standard treatment for the hormone deficiency itself but may be needed for associated or underlying structural problems.

1. Surgery for pituitary or hypothalamic tumors
   In rare secondary or tertiary hypothyroidism due to brain or pituitary tumors, neurosurgery may be needed to remove the mass. The purpose is to relieve pressure, prevent further brain damage, and sometimes restore pituitary function. Even after surgery, many children still need levothyroxine replacement and other pituitary hormone support.ScienceDirect+1

2. Thyroid surgery for structural anomalies or nodules
   Some congenital thyroid abnormalities can include large goiters or nodules. Very rarely, surgery might be needed if the neck mass causes breathing or swallowing problems or raises concern for cancer. The procedure removes part or all of the thyroid, after which the child will completely rely on levothyroxine replacement for life.FDA Access Data+1

3. Surgery for associated congenital heart disease
   Children with congenital hypothyroidism may also have unrelated heart defects. Cardiac surgery in infancy or childhood aims to correct these defects, improve circulation, and support normal growth. Good thyroid control before and after surgery is important for recovery, so endocrinology and cardiology teams coordinate care.ETJ+1

4. Surgery for craniofacial or airway anomalies
   If a child has craniofacial abnormalities or airway problems that affect feeding or breathing, surgical repair may be necessary. Correcting these issues improves nutrition and oxygenation, which, together with proper thyroid hormone replacement, supports brain development and physical growth.ETJ+1

5. Diagnostic surgery or biopsy in complex cases
   In unusual or complex cases, surgeons may perform a biopsy or remove tissue to clarify the diagnosis of a thyroid or pituitary lesion. This helps guide long-term treatment planning. Again, surgery is aimed at the underlying structure; levothyroxine remains the core therapy for hormone deficiency.FDA Access Data+1

Prevention of congenital hypothyroidism and its complications

1. Universal newborn screening
   The main way to prevent the complications of congenital hypothyroidism is to screen all newborns with a heel-prick blood test and act quickly on abnormal results. This prevents missed or late diagnoses and protects against intellectual disability.AAP Publications+2AAP Publications+2

2. Adequate iodine intake in pregnancy
   Ensuring that women of childbearing age and pregnant women have enough iodine—usually through iodized salt or prenatal vitamins—helps the fetus build and use thyroid hormone normally and reduces some causes of neonatal hypothyroidism.IAEA Publications+1

3. Good control of maternal thyroid disease
   Women with hypothyroidism or Graves’ disease should have their thyroid levels well controlled before conception and during pregnancy. Adjusting levothyroxine or anti-thyroid drug doses under medical supervision helps protect fetal thyroid function and brain development.American Thyroid Association+1

4. Avoiding harmful drugs in pregnancy
   Some medications, such as high doses of anti-thyroid drugs, radioiodine, or certain immunotherapies, can affect the fetal thyroid. Pregnant women and those planning pregnancy should review all medicines with their doctors to avoid exposing the baby’s thyroid to harmful agents whenever possible.ETJ+1

5. Public health iodine programs
   National or regional iodized salt programs and monitoring of population iodine status help prevent iodine deficiency disorders, including congenital hypothyroidism caused by lack of iodine.IAEA Publications+1

6. Prompt follow-up of abnormal screening results
   When screening shows elevated TSH or low T4, quick recall for confirmatory tests and early treatment prevents long delays. Clear communication systems between laboratories, clinics, and families are a key prevention step.PMC+1

7. Continuous access to levothyroxine
   Health-system planning to ensure reliable availability and affordability of levothyroxine prevents treatment interruption. For families, keeping extra tablets, knowing how to refill prescriptions, and planning for travel help prevent missed doses.Bangladesh Journals Online+1

8. Regular monitoring and dose adjustment
   Preventing complications such as poor growth, learning problems, or symptoms of excess thyroid hormone depends on regular blood tests and clinical reviews to keep TSH and free T4 in the target range.Medscape+1

9. Education about drug and food interactions
   Teaching families to avoid giving levothyroxine with soy, iron, calcium, or fiber-rich meals helps prevent under-treatment due to poor absorption. Written instructions, reminder apps, and pharmacist counseling support this prevention step.PMC+1

10. Transition support into adult care
    Preventing loss to follow-up in adolescence requires planned transfer from pediatric to adult endocrine services. Teaching the young person about their condition and medication needs helps maintain lifelong therapy and prevents adult complications such as infertility, depression, and cardiovascular risk from untreated hypothyroidism.ScienceDirect+1

When to see doctors

Parents should see a doctor urgently if a baby has prolonged jaundice, poor feeding, excessive sleepiness, constipation, low temperature, or puffy face and tongue—especially if newborn screening results are delayed or unknown. These can be signs of untreated congenital hypothyroidism.AAP Publications+1

For children already on levothyroxine, medical review is needed if they miss several doses, have sudden weight loss, fast heartbeat, sweating, or irritability (possible over-treatment), or if they are tired, gaining weight, cold, or constipated (possible under-treatment). Regularly scheduled visits with a pediatric endocrinologist are essential even when the child seems well, because lab tests can detect problems before symptoms appear.Medscape+2Journal of Pediatrics+2

What to eat and what to avoid

1. Eat: Balanced diet with fruits, vegetables, grains, and protein – supports growth and immune function.PMC+1

2. Eat: Iodized salt in normal amounts for the household – maintains adequate iodine intake without excess.IAEA Publications+1

3. Eat: Foods rich in iron (meat, beans, lentils, leafy greens) – help prevent anemia and support energy.PMC+1

4. Eat: Dairy products and fortified foods for calcium and vitamin D – protect bones, especially when thyroid levels are well controlled.ScienceDirect+1

5. Eat: Oily fish or other omega-3 sources when age-appropriate – support brain and eye development.PMC+1

6. Avoid: Giving levothyroxine with soy formula or soy-rich meals – soy can reduce absorption; separate in time.American Thyroid Association+1

7. Avoid: Giving medicine at the same time as iron, calcium, or multivitamins – these may bind the hormone in the gut; space them by several hours.PMC+1

8. Avoid: Very high iodine supplements (seaweed tablets, large kelp products) unless prescribed – excess iodine can worsen thyroid problems.IAEA Publications+1

9. Avoid: Extreme “thyroid diets” or unregulated herbal products claiming to treat hypothyroidism – many are untested or contain hidden thyroid hormone.PMC+1

10. Avoid: Regular high-sugar, high-fat junk food – it does not directly affect thyroid hormone, but it can lead to weight and metabolic issues that complicate care.ScienceDirect+1

Frequently asked questions

1. Can congenital hypothyroidism be cured?
   Most children with congenital hypothyroidism need lifelong levothyroxine, but with proper treatment their growth and intelligence are usually normal. In some transient forms, thyroid function recovers and medicine can sometimes be stopped after careful testing at 3–5 years.Translational Pediatrics+1

2. Will my child have normal intelligence and go to a regular school?
   If treatment starts very early and hormone levels are kept in the target range, most children have normal neurodevelopment and attend regular school. Mild learning or attention problems can occur, especially in severe cases or when therapy was delayed, so monitoring and school support are important.PMC+2Healthcare Bulletin+2

3. How long will my child need to take levothyroxine?
   Many children take levothyroxine for life. Around age 3–5, doctors may re-evaluate some children—especially those with mild or uncertain forms—to see if the thyroid works on its own. If tests confirm permanent hypothyroidism, lifelong therapy is recommended.ResearchGate+1

4. Is it dangerous if we miss a dose?
   A single missed dose usually is not an emergency; parents can give the next dose at the usual time and tell the doctor if doses are missed often. Frequent missed doses over weeks or months can lead to poor growth and learning problems, so systems like alarms or pill boxes are helpful.Medscape+1

5. Why are blood tests needed so often?
   Babies grow quickly and their hormone needs change fast. Regular TSH and free T4 tests allow doctors to adjust dose before symptoms appear. As the child grows older, tests can be spaced further apart, but lifelong monitoring remains important.Medscape+1

6. Can we switch between different brands or forms of levothyroxine?
   Switching between tablets, capsules, or solutions can change how much hormone the body absorbs. If a switch is necessary, doctors often recheck blood tests after a few weeks and adjust the dose if needed. It is best to stay with one product consistently when possible.PMC+1

7. Does congenital hypothyroidism affect height and puberty?
   If treatment is started early and kept optimal, most children reach a normal adult height and go through puberty at the usual time. Poorly controlled hypothyroidism can slow growth and delay puberty, which is why regular endocrine follow-up is essential.ScienceDirect+1

8. Can my child play sports and live a normal life?
   Yes. With good treatment, children with congenital hypothyroidism can be physically active, play all normal sports, and live full lives. The key is taking medicine regularly, eating a healthy diet, and attending follow-up appointments.Bangladesh Journals Online+1

9. Is congenital hypothyroidism genetic?
   In some cases it is caused by gene changes affecting thyroid development or hormone production; in others it is sporadic without a clear inheritance pattern. Genetic testing can sometimes identify the cause and inform counseling about risks in future pregnancies.ETJ+1

10. Will my next baby also have congenital hypothyroidism?
    The risk of recurrence depends on the underlying cause. If a specific genetic defect is identified, recurrence risk may be higher. Regardless, newborn screening will be done again in future pregnancies, and doctors may monitor more closely if there is a history of congenital hypothyroidism.ETJ+1

11. Can we use natural thyroid or animal thyroid extracts?
    Guidelines clearly recommend synthetic levothyroxine (T4) rather than desiccated thyroid or mixed T3/T4 products in infants and children. Natural extracts can have variable hormone content and higher risk of over- or under-dosing, which is particularly dangerous for the developing brain.ScienceDirect+1

12. Are there long-term side effects from levothyroxine?
    When dosed correctly, levothyroxine is simply replacing a missing natural hormone and is considered safe long term. Problems arise mainly from chronic over-treatment (risk to heart and bones) or under-treatment (risk to brain and growth). This is why careful dosing and monitoring are vital.FDA Access Data+2FDA Access Data+2

13. Can supplements like iodine, selenium, or herbal products replace levothyroxine?
    No. In congenital hypothyroidism, the thyroid gland cannot produce enough hormone, so only levothyroxine can fully replace T4. Supplements may support general health but do not correct the hormone deficiency and must never be used as a substitute for prescribed therapy.PMC+2IAEA Publications+2

14. What happens if congenital hypothyroidism is not treated?
    Without treatment, congenital hypothyroidism causes serious and permanent intellectual disability, growth failure, and multiple health problems. Newborn screening and levothyroxine therapy have transformed outcomes, making untreated cases rare in countries with good screening programs.AAP Publications+2AAP Publications+2

15. Who should manage my child’s congenital hypothyroidism?
    A pediatric endocrinologist, working with your primary care doctor, is usually the best person to manage congenital hypothyroidism. They are trained to adjust doses, interpret tests, and coordinate developmental support. Regular communication between the medical team and family is the foundation of safe, effective care.ScienceDirect+1

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Last Updated: December o2 , 2025.