Congenital hypothyroidism is a condition where a newborn’s thyroid gland does not produce enough thyroid hormone. This hormone is important for brain development and physical growth. The condition is typically identified through routine newborn screening tests, usually performed within the first few days or weeks of life. With early diagnosis and consistent treatment, congenital hypothyroidism is a highly manageable condition, allowing most affected babies to lead full, healthy lives.
Standard Treatment with Levothyroxine
Treatment for congenital hypothyroidism involves daily thyroid hormone replacement therapy using a medication called levothyroxine. This medication is typically given in a small pill form, crushed for infants. The crushed pill should be mixed with a very small amount of liquid, such as 0.2 milliliters of sterile water, breast milk, or formula. Avoid mixing the medication into an entire bottle of liquid, as the baby might not consume the full dose.
Administer the mixture to the infant using a dropper, needleless syringe, or a small spoon, ensuring the entire dose is consumed. Giving the medication at the same time each day helps maintain consistent hormone levels. Ideally, levothyroxine should be given at least 30 to 60 minutes before a feeding, as food can sometimes interfere with its absorption.
Certain substances like soy formula, calcium, or iron supplements can also reduce levothyroxine absorption; separate their administration by at least three to four hours. If a dose is missed, give it as soon as remembered, but never double the next dose. Should the baby vomit within 30 minutes of receiving the dose, it is advisable to repeat the dose; if vomiting occurs more than 30 minutes later, repeating the dose is generally not necessary.
Ongoing Monitoring and Dose Adjustment
Treatment requires ongoing monitoring and dose adjustments as a child grows. Regular follow-up appointments with a pediatric endocrinologist ensure treatment remains effective. During these visits, blood tests are performed to measure thyroid-stimulating hormone (TSH) and thyroxine (T4 or free T4) levels.
The aim is to maintain TSH levels within the normal range for the child’s age, while keeping T4 or free T4 levels in the upper half of the normal range. Blood tests are typically frequent in the initial months, often every two to four weeks after starting treatment, then every one to two months during the first six months of life. After six months, testing frequency may decrease to every three to four months until the child reaches about three years of age, and subsequently every six to twelve months until growth is complete.
The levothyroxine dosage will be adjusted periodically by the specialist based on these blood test results and the child’s increasing weight. Blood tests are generally repeated approximately two to four weeks after any change in medication dosage to confirm the new dose is appropriate. If T4 levels do not rise into the upper half of the normal range within two weeks, or if TSH does not decrease below 20 mU/L within four weeks of starting therapy, it may indicate that the current treatment is not sufficient.
Goals and Prognosis with Treatment
The primary goal is to ensure normal brain development, preventing the potential for permanent intellectual disability that could occur if the condition went untreated. Early initiation of levothyroxine treatment, ideally within the first two weeks of life, is associated with optimal neurodevelopmental outcomes. Supporting normal physical growth and development is another significant goal of consistent therapy.
With early diagnosis and diligent, properly monitored treatment, the vast majority of children with congenital hypothyroidism grow and develop without significant issues. Most children achieve normal intelligence, enabling them to lead full, healthy lives. While some studies have noted that a small percentage of adults who had severe congenital hypothyroidism may experience mild differences in memory, verbal, or attention skills, even with early intervention, the overall prognosis remains positive. Children diagnosed with athyreosis, which is the complete absence of the thyroid gland, or those from lower socioeconomic backgrounds, might face a slightly higher risk for less favorable outcomes; however, the general outlook with treatment is very encouraging.
Recognizing Signs of Improper Dosing
Parents can play an active role in their child’s care by recognizing signs that might suggest the levothyroxine dose needs adjustment between doctor visits. Observing these signs can help ensure the child receives the most appropriate amount of thyroid hormone.
Signs that may indicate undertreatment, meaning the child is receiving too little thyroid hormone, include excessive sleepiness, a reduced interest in feeding, poor muscle tone, a hoarse cry, constipation, dry skin, and poor growth or weight gain.
Conversely, symptoms that might suggest overtreatment, meaning too much thyroid hormone, include irritability, nervousness, difficulty sleeping, an increased heart rate or palpitations, excessive sweating, tremors, diarrhea, and unexplained weight loss.
Any of these symptoms should be reported to the pediatric endocrinologist for further evaluation and potential dose adjustment. While a temporary loss of hair can sometimes occur during the first few months of levothyroxine therapy, any persistent or concerning symptoms warrant prompt medical attention.