Diagnosis of Congenital Hypothyroidism

NYU Langone pediatric endocrinologists—specialists in treating conditions involving the endocrine glands and hormones—are experienced in diagnosing congenital hypothyroidism, a condition in which a child is born with a severe deficiency or complete absence of thyroid function.

The thyroid is a small, butterfly-shaped gland located in the front of the neck. It makes two hormones—thyroxine (T4) and triiodothyronine (T3). These hormones help the body transform food into energy, a process called metabolism. Thyroid hormones play an important role in a baby’s brain development and growth.

In most babies with congenital hypothyroidism, the thyroid gland did not form completely during development in the womb. As a result, the gland cannot produce enough thyroid hormone. Other children with this condition are born with a normal-size thyroid that cannot make enough thyroid hormone. 

Usually, congenital hypothyroidism is not caused by an inherited condition, and doctors are not sure why it occurs. A newborn may have a temporary interruption in thyroid function if he or she was exposed to antibodies that attack the thyroid in the womb, which can happen when an expectant mother has an autoimmune thyroid disorder. However, this interruption, does not affect thyroid formation or function later on. 

Newborns with the condition rarely have symptoms. An older baby who has a severe reduction in thyroid hormones may be less active and have delayed reflexes, poor muscle tone, an enlarged tongue, and a larger-than-normal soft spot, called a fontanel, on the top of the head.

If you’re told that your baby’s screening test result is abnormal, our doctors swiftly examine your child to make an accurate diagnosis. 

Physical Exam

In a physical exam, the doctor feels the baby’s neck to identify the location and shape of the thyroid. The doctor may also examine your baby for physical signs, such as poor muscle tone, which may be caused by a lack of thyroid hormone during development in the womb. 

Blood Tests

Blood tests are performed to confirm that your baby has low levels of T4 or high levels of TSH, a hormone made by the pituitary gland that tells the thyroid when to make more thyroid hormones. Blood tests also measure levels of T3, which may be low in babies with hypothyroidism. 

Having the proper balance of these hormones is essential to ensure typical growth and development during childhood—and a properly regulated metabolism throughout life. 

Thyroid Ultrasound

An ultrasound, which uses sound waves to create a picture of internal organs, allows the doctor to see the shape and location of your baby’s thyroid. This test can help to determine if your baby’s thyroid is unusually small or in an atypical location.

Leg X-ray

X-rays are sometimes used to get a picture of the long bones in the leg. Delayed development of these bones may indicate that your child had too little thyroid hormone while in the womb.

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