Diagnosis and Treatment of Congenital Hypothyroidism

Diagnosis

In most cases, diagnosis is made through newborn screening by measuring thyroid-stimulating hormone (TSH) and thyroid hormone levels. If the problem is primarily in the thyroid gland, TSH levels are elevated and thyroid hormone levels are decreased. If thyroid function is reduced due to a problem in the pituitary gland or hypothalamus, both may be decreased. In addition, a thyroid scan and ultrasound can be performed to determine whether the thyroid tissue is properly formed, what its size is, and where it is located, helping to identify the cause. Bone X-rays can also be taken to check whether bone age is delayed and whether there are any abnormalities in bone formation.

Newborn Screening

Because congenital hypothyroidism usually does not show clinical symptoms in early infancy, it is difficult to detect and treat early, which can lead to a serious permanent consequence: intellectual disability. Therefore, newborn screening is necessary to detect and treat it early and prevent possible sequelae. The best time for newborn screening is 5-7 days after birth, but at a minimum it is recommended to perform it at 48 hours after birth, when thyroid hormone levels are already approaching adult normal levels to some extent.

For the test, a few drops of blood are collected from the baby’s heel 3-7 days after birth, soaked onto filter paper, and sent to a newborn screening laboratory. If the test results show abnormal levels in one or both of the thyroid hormone and thyroid-stimulating hormone levels in the blood, congenital hypothyroidism is suspected.

When the results suggest the disease, a more detailed examination is performed again in the pediatric department at 2-6 weeks of age to confirm the diagnosis. In Korea, free screening is performed for congenital hypothyroidism in all newborns, and many patients are detected early and receive treatment.

Treatment

1. Treatment

At present, the most widely used standard treatment is the thyroid hormone preparation sodium levothyroxine. The most important point in treatment is to begin therapy as soon as possible after birth and to take the correct dose of thyroid hormone continuously. The dose of thyroid hormone should be adjusted appropriately according to clinical symptoms, the degree of improvement, thyroid function test results, growth and developmental status, and increases in bone age.

Thyroid hormone preparations come only in small tablets. If possible, it is best to crush the tablet with two spoons and mix it with a small amount of room-temperature water or breast milk before giving it. Do not mix it with hot or cold water, or take it together with soy products such as soy milk, or with calcium or iron supplements. These can prevent the hormone from being absorbed in the stomach, causing hormone levels to remain low. However, no special diet is otherwise necessary.

Give the medicine slowly into the inside of the child’s cheek using a syringe or spoon. Never put it into a bottle. If the child does not finish the milk, the medicine may not be fully taken, and some may remain on the surface or bottom of the bottle. If the child can chew and swallow it like a candy, the tablet can be given as is. If the child tends to vomit easily, the medicine should be given about 30 minutes before feeding.

It is also important to visit the hospital according to the regular follow-up schedule and have blood levels checked regularly to confirm that the correct dose is being given. It is necessary to determine whether the child is growing normally and to observe whether signs of thyroid hormone deficiency are present, such as constipation, dry skin or hair, or being listless and sleepy, in order to assess whether the thyroid hormone level is appropriate. The dose of thyroid hormone medication varies greatly from person to person and is adjusted based on blood tests, growth and developmental status, and bone age.

After thyroid hormone treatment begins, activity level increases, sleep time decreases, and appetite improves, leading to more active feeding. If thyroid hormone is taken regularly from an early stage, the baby’s development can proceed normally and the child can grow into a healthy adult. Other than the need to take thyroid hormone, there is no special difference from other children. Thyroid hormone tests are generally performed monthly until 6 months of age, every 1-2 months between 6 months and 1 year of age, every 2-3 months until 3 years of age, and then every 3-12 months until growth is complete to assess whether the correct dose is being taken. Bone age is also observed regularly to determine whether growth is progressing normally. To assess development, psychomotor testing is recommended at 12-18 months and then every 2 years thereafter.

In cases where the thyroid gland is not formed at all, is underdeveloped, or is located elsewhere, and in some cases of disorders of thyroid hormone synthesis and secretion, thyroid hormone preparations must be taken for life. However, if the diagnosis was unclear early on or treatment was started without a definite cause being identified, hormone testing is performed after stopping medication for 3-4 weeks after 3 years of age to determine the cause.

2. Prognosis

After newborn screening was introduced, hypothyroidism is detected more quickly, and the prognosis has become much better. It is now possible to diagnose it early and start appropriate treatment promptly, allowing normal growth and intellectual development. The cause of hypothyroidism, when it began, when treatment started, and the thyroid hormone level at the time of initial diagnosis can all affect the prognosis.

If treatment begins within 6 weeks after birth, most infants do not show intellectual disability or neurological symptoms. However, if thyroid hormone levels were very low at diagnosis or if early diagnosis and treatment were not achieved, intellectual disability may occur and brain dysfunction may develop, leading to strabismus, speech impairment, poor attention, behavioral problems, learning difficulties, and impaired coordination. In about 20% of cases, sensorineural hearing impairment may also occur. In general, the earlier treatment can be started, the greater the chance that the brain will develop normally.

So far, we have covered the diagnosis and treatment of congenital hypothyroidism.

In the next installment, we will learn about gastritis.

Source: Korea Centers for Disease Control and Prevention, National Health Information Portal