Seeing that many parents mention the problem of hypothyroidism found in newborns, although not a pediatric endocrinologist, I summarized the congenital hypothyroidism aspect, hoping that it will help parents with their confusion.
Basic knowledge
What is congenital hypothyroidism.
To put it simply: congenital hypothyroidism is caused by some kind of deficiency of thyroid hormones in the body, a condition that begins at birth.
A more professional answer: Congenital hypothyroidism is an endocrine disease that causes impaired neurological and physical development in children due to hypothyroidism or impaired synthesis of thyroid hormones, and is one of the main causes of mental retardation in children.
What is the incidence of congenital hypothyroidism?
The incidence of congenital hypothyroidism: 1:2000-1:4000, is one of the most common preventable causes of mental retardation.
What are the causes of congenital hypothyroidism?
In general, 85% of congenital hypothyroidism is disseminated and 15% is hereditary (most commonly affecting thyroid hormone synthesis)
*The exact cause needs to be determined after a detailed history, examination and evaluation
What are the symptoms of congenital hypothyroidism in infants?
1. Most infants are asymptomatic
2. If symptomatic, they may present as
3. not as active as other infants
4. Slow activity
5. hoarse crying
6.Eating problems
7.Constipation
8.Rare symptoms – enlarged tongue, enlarged umbilicus
9.Weakness of muscles compared to the same age
10.Dry skin
11, easily afraid of cold
12.Jaundice
How do I know if my child has congenital hypothyroidism?
If there is any abnormality, further testing is needed to clarify the thyroid function and the cause of congenital hypothyroidism.
What are the normal changes in thyroid axis hormones in newborns?
The following table shows: changes in fetal (after 12 weeks) and neonatal TSH, total T4 and total T3 (T3*0.01536 converted from ng/dl to nmol/l; T4*12.87 converted from mcg/dl to nmol/l)
In general, TSH and T4 changes after birth in newborns are as follows.
Serum TSH concentration rises rapidly to 60-80mIU/L 30 minutes after birth, decreases to 20mIU/L 24 hours after birth, and slowly decreases to 6-10mIU/l in about 1 week. TSH >10Miu/l is abnormal after one week of birth in newborns.
At 1-4 days of life, the normal range of total T4 concentration is 10-22mcg/dl (129-283nmol/l); free T4 level is 2-5ng/dl (25-64pmol/l)
4 weeks after birth, total T4 ranges from 7-16mcg/dl (90-206nmol/l); free T4 level is 0.8-2ng/dl (10-26pmol/l)
How is congenital hypothyroidism treated after it is clearly identified?
Once congenital hypothyroidism is diagnosed, daily application of thyroxine is required.
The tablets are pressed into a powder and mixed with breast milk, formula or water for feeding.
Note for feeding the medication.
Do not mix with soy-based dairy products
Do not change the dose at will. Too much can cause heart problems, too little hypothyroidism is not corrected and can affect mental development.
Daily application
Children with congenital hypothyroidism need regular follow-up thyroid function tests. The follow-up period needs to be consulted with the doctor.
Will the child’s future life be affected?
Most children with congenital hypothyroidism are able to live a normal life if their thyroid function is detected and corrected to normal after birth.
It is especially important for infants and children to have adequate amounts of thyroid hormones. Thyroid hormones help the brain develop, and if a child’s brain does not get enough thyroid hormones, he or she will have learning problems that will affect the ability to think, learn, and go about daily life for the rest of their lives.
If there are other abnormalities in addition to thyroid problems, management is more complex and the prognosis varies depending on the appropriate disease.
Advanced knowledge
If you would like to learn more about this, you can continue to learn about it.
A few concepts mentioned.
Primary hypothyroidism.
Hypothyroidism caused by a lesion in the thyroid gland itself is called primary hypothyroidism
Regarding central hypothyroidism.
Central hypothyroidism refers to a defect in TSH production due to hypothalamic or pituitary disorders.
Some are associated with other congenital syndromes, particularly midline defects such as optic nerve hypoplasia/optic septal hypoplasia, and midline cleft lip and palate defects.
Rarely, the cause is a TRH mutation, a TRH receptor mutation or a TSH mutation.
Other pituitary hormone deficiencies may be present
It can also be due to poor control of maternal Graves’ disease during pregnancy
Regarding transient hypothyroidism.
Transient hypothyroidism can be seen in the following conditions.
Iodine deficiency
Maternal blocking antibodies: TRAB transported through the placenta
Maternal antihyperthyroid drugs (antihyperthyroid drugs can pass through the placenta into the fetal circulation, these drugs can be cleared after a few days and the child’s thyroid function will improve after a few weeks postpartum)
Iodine overdose: This can be seen when the mother is taking amiodarone to control cardiac arrhythmias, or when the mother or infant is taking other iodine-containing medications, or when iodine contrast is used for examinations.
Large hepatic hemangiomas: Large hepatic hemangiomas can produce high levels of type 3 deiodinase, causing “wasting hypothyroidism”.
Mutations in the DUOX1 and DUOX2 genes – mutations in this gene are associated with the production of hydrogen peroxide, which is required for the action of thyroid peroxidase in the synthesis of thyroid hormones.