What Is Congenital Hypothyroidism?

Congenital hypothyroidism is a serious disease that has no definitive cure. It's crucial to detect it early in order to administer medication to prevent serious consequences in the child's development.

Reviewed and approved by the doctor Leonardo Biolatto.

Written by Edith Sánchez

Last update: 27 March, 2023

Congenital hypothyroidism occurs when a baby doesn’t have the ability to produce normal amounts of thyroid hormone at birth. Sometimes there’s a decrease in the production of the substance, and sometimes there’s none at all.

The word congenital implies that the condition is present from the moment of birth, so the baby is born with deficient activity of the thyroid gland. Statistics indicate that 1 in 3000 to 4000 children suffer from the pathology.

Congenital hypothyroidism is linked to preventable mental retardation. This is because the thyroid hormone plays a very important role in the brain development of children. So treatment should occur early on to prevent intellectual disabilities.

About the thyroid gland

The thyroid gland is an organ of vital importance to the development and functioning of the body. It’s located in the neck, in the front of the windpipe. It secretes hormones to support the energy metabolism of the cells.

The thyroid is shaped like a butterfly and plays a hormonal role. It’s in charge of regulating processes such as calorie burning, for example. Its most frequent problems are enlargement, which we call goiter, hyperthyroidism, which is the excess in hormone production, and hypothyroidism, which is the deficiency in its functioning.

In the case of congenital or neonatal hypothyroidism, if it isn’t detected and treated in time, it can cause irreversible neurological disorders and growth problems. It’s a condition that, in most cases, will require lifelong medical treatment.

Symptoms of congenital hypothyroidism

To summarize the symptoms of congenital hypothyroidism, we have prepared this list, which we’ll explain in detail later:

• Jaundice
• Constipation
• Weak muscle tone
• Numbness or lethargy
• Voice changes when crying
• Various soft tissue edema
• Swollen tongue with fluid retention

One of the signs that could alert to the presence of congenital hypothyroidism in a newborn is jaundice, which is the yellowish color that appears on the skin and mucous membranes. If this condition is present, and especially if it’s prolonged, the pediatrician should be consulted without delay.

Another sign that suggests the presence of the disease is a hoarse or weak cry, which comes from the pressure exerted by the enlarged gland on the vocal cord area. This hinders the movement of air through the region and, therefore, the formation of sounds. According to research, even if the child later receives treatment, his or her speech may be affected in the future.

Children with congenital hypothyroidism are excessively sleepy and lethargic. They respond more slowly to stimuli because cellular metabolism is running at a slower rate. This results in poor feeding due to listlessness and asthenia.

Their faces are usually swollen, which also implies the enlargement of the tongue, which occupies more space in the oral cavity. The situation also has an impact on feeding, together with digestive changes that often result in constipation.

Muscle tone is greatly diminished in them. Pediatricians often recognize the lack of reflexes in the lower limbs and the arrest of postural development before the age of two years.

At birth, infants don’t usually show clear clinical signs of congenital hypothyroidism.

Possible causes of the condition

In summary, the causes of congenital hypothyroidism can be classified as follows:

• Maternal origin: Medication taken by the mother that affected fetal development, or a lack of iodine in the maternal diet.
• Due to embryological developmental problems: The gland doesn’t form in the baby or doesn’t produce enough thyroid stimulating hormones.
• Autoimmune: Antibodies appear that attack the baby’s gland, while they’re in the mother’s womb. They’re usually antibodies made by the mother herself, although they may also be from the fetus’s incipient immune system.

Congenital hypothyroidism may be related to late-term birth. It’s known that deficient development during gestation, or the absence of the thyroid gland due to a hereditary defect, are possible origins.

Likewise, the location of the gland could be abnormal, which could prevent its functionality. Whenever the organ is deficient in the production of hormones, or the hormones are unable to carry out their function in the peripheral tissues, there’ll be symptoms.

Some studies relate the appearance of this disease to the use of some medication ingested by the mother during pregnancy. Another factor of incidence is the lack of iodine in the maternal diet.

In most cases there’s no hereditary component. Therefore, a case of this type in the family doesn’t imply an increased risk of having children with this disease.

Diagnosis

Due to the seriousness of congenital hypothyroidism for infants, several countries carry out screening for newborns. This involves looking for alterations in thyroid hormones in all infants during the first days of their lives.

They don’t only screen for thyroid disease, but also for other conditions. It’s common for the test to be colloquially called a heel prick, since blood is obtained from the newborn’s heel to send to the laboratory.

The following diseases can be tested for in a heel prick test:

• Phenylketonuria
• Cystic fibrosis
• Glutaric aciduria type I
• Congenital hypothyroidism
• Biotinidase deficiency
• Sickle cell anemia
• Medium chain fatty acid acyl CoA dehydrogenase deficiency
• Long-chain fatty acid 3-hydroxy acyl CoA dehydrogenase deficiency

Neonatal screening for hypothyroidism is a law in many countries, making it a mandatory practice.

The heel blood sample is taken within 24 hours of birth to improve the quality of the drops to be obtained from the infant. The results usually take no more than 7 days to be ready.

Treatment for congenital hypothyroidism

In most cases, congenital hypothyroidism must be treated for life. Medicine doesn’t have a cure today and the possibility of preventing the disorder doesn’t go beyond taking care of the diet and controlling the medications taken during pregnancy.

This pathology is treated by replacing the hormone that isn’t produced by the baby’s body. The baby is given a medication that replaces the missing thyroid hormone, which is usually artificial levothyroxine.

Usually, the doctor orders the use of the medication from the first two weeks of life. In this way, proper growth and neurodevelopment is achieved. It’s very important to follow all the indications, as the success and quality of life of the child depends on it.