Symptoms and forms of congenital hypothyroidism

Genetically determined anomalies of thyroid gland development can be diagnosed at different ages, depending on the severity of the disease and its form. In case of aplasia or severe hypoplasia, symptoms of the disorder are noticeable in the first week of the baby's life. While dystopia and minor hypoplasia appear as the baby grows older, usually after one year.

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Symptoms

The main symptoms of congenital hypothyroidism include:

• Prematurity (birth before 38 weeks of gestation).
• Post-term baby.
• Delayed passage of meconium.
• The newborn's weight is more than 4 kg.
• Long-term physiological jaundice.
• Apnea during feeding.
• Muscle atony.
• Flatulence, tendency to constipation and frequent regurgitation.
• Hyporeflexia.
• Enlarged tongue and fontanelles.
• Apathy.
• Hip dysplasia.
• Coldness of the skin.
• Swelling of the limbs and genitals.
• A rough and low-pitched voice when crying.
• Long and difficult healing of the navel, hernia.

Gradually, the primary form of the disease begins to progress, and pathological symptoms intensify:

• The skin is dry and thickened.
• The fabrics are yellowish-gray in color.
• Myxedema (swelling of the subcutaneous tissue and skin).
• Sweating is reduced.
• Hair and nails are atrophied.
• The voice is rough, hoarse and low.
• Delayed psychomotor development.

The symptoms of central forms of congenital hypothyroidism, i.e. secondary and tertiary, are not clearly expressed. The disease occurs with a deficiency of other hormones (somatotropic, luteinizing, follicle-stimulating) and anomalies in the structure of the facial skull.

Without timely treatment, acute thyroid hormone deficiency causes irreversible consequences in neuropsychic development. Newborns experience significant retardation in physical and mental development, i.e. cretinism. The main symptoms of this complication include: short stature, facial anomalies, abnormal limb development, chronic diseases and frequent colds.

Congenital hypothyroidism in children

The main cause of congenital thyroid pathologies is autoimmune reactions. Autoimmune thyroiditis is a condition in which the immune system gradually destroys the thyroid gland. This occurs due to the activity of antibodies in the female body or due to the treatment of endocrine diseases during pregnancy.

There are also a number of factors that increase the risk of developing congenital hypothyroidism:

• Chromosomal diseases: Down syndrome, Williams syndrome, Shereshevsky syndrome.
• Autoimmune pathologies: diabetes, celiac disease.
• Thyroid injuries.

The disease may be asymptomatic or accompanied by the following signs: yellowing of the skin and eyes, hoarse crying, poor appetite, umbilical hernia, weak muscle tone and slow bone growth, constipation, swelling of the face and a large tongue.

After birth, all babies are checked for serious pathologies during the first few days. For this, a blood test is performed from the baby's heel. The blood is checked for the amount of thyroid hormones in order to determine how well the thyroid is working.

The symptoms of the disease become more pronounced when the child reaches 3-6 months of age:

• Slow growth.
• Delay in neuropsychic development.
• Disproportionate body type.
• Mucinous edema of the eyelids.
• Thickened lips, tongue and nostrils.
• Umbilical hernia.
• Muffled heart sounds and bradycardia.
• The thyroid gland is enlarged or difficult to palpate.

If any violations are detected, the doctor will prescribe a course of treatment. The child is prescribed daily intake of synthetic hormones. In some cases, the organ begins to work independently; if this does not happen, the drugs are taken on a long-term basis. Congenital diseases can worsen the normal growth and development of the baby, so it is very important that the medications are continued until full puberty. If the pathology is left untreated, it can lead to serious complications.

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Congenital hypothyroidism in newborns

Medical statistics indicate that in 75-90% of cases, thyroid gland dysfunction in newborns occurs due to organ development defects. The baby's thyroid gland weighs about 2 g. Aplasia or hypoplasia is formed during intrauterine development, approximately at 4-9 weeks of pregnancy. By the end of the first trimester, the fetal thyroid gland independently accumulates iodine and synthesizes thyroid hormones.

The main causes of genetic disorders are:

• Viral diseases of the mother during pregnancy.
• Toxic effects of drugs or chemicals.
• Exposure of a pregnant woman to radioactive iodine.
• Disorders of the hypothalamic-pituitary system.

Transient hypothyroidism may be part of the body's adaptation to new living conditions or indicate iodine deficiency. The above causes lead to a significant decrease in the level of thyroid hormones, which entails a weakening of their biological effectiveness. This is reflected in the weakening of cell and tissue growth. The changes also affect the central nervous system.

It is difficult to identify the disease in its early stages, as it has many different symptoms that parents mistake for the physiological state of the baby or signs of other diseases. Characteristic symptoms of the disorder are:

• Newborns with increased body weight.
• Asphyxia during the birth process.
• Severe jaundice lasting more than 10 days.
• Decreased motor activity and sucking.
• Low body temperature.
• Constipation and flatulence.
• Anemia.
• Swelling of the face and body.

To determine the disease, a set of laboratory and instrumental studies is carried out. The diagnosis is confirmed if the TSH in the blood serum exceeds 20 μU/ml. The anomaly is necessarily differentiated from birth injuries, rickets, jaundice, Down syndrome and other disorders. Treatment is long-term, in especially severe cases, surgical intervention may be required.

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Forms

Congenital hypothyroidism has several types, which are classified according to several characteristics.

By origin:

• Primary (thyrogenic) – pathological changes occur directly in the tissues of the organ.
• Secondary – occurs due to a malfunction of the adenohypophysis, which leads to a deficiency in the production of thyroid-stimulating hormone.
• Tertiary - thyroid insufficiency due to deficiency of the hormone thyroliberin (produced by the hypothalamus). This type, like secondary, refers to central hypothyroidism.
• Peripheral – disruption or absence of receptors in tropic tissues, failure in the conversion of thyroxine and triiodothyronine.

According to the severity of clinical symptoms and the level of thyroxine T4 in the blood plasma:

• Latent (subclinical) – normal thyroxine level against the background of elevated TSH. There are no pronounced symptoms or they are barely noticeable.
• Manifest - the thyroxine level is reduced against the background of increased TSH, the standard symptomatic picture of the disease develops.
• Complicated - high TSH level and pronounced T4 deficiency. In addition to signs of thyroid insufficiency, there are disorders of the cardiovascular system, polyserositis, cretinism, coma, and in rare cases - pituitary adenoma.

By treatment effectiveness:

• Compensated – therapy reduces the symptoms of the disease, the concentration of hormones TSH, T3 and T4 is restored.
• Decompensated – after a course of treatment, clinical and laboratory signs of the disease remain.

Based on duration, congenital hypothyroidism is divided into:

• Transient – develops under the influence of maternal antibodies to the child’s TSH, lasting from a week to 1 month.
• Permanent – lifelong replacement therapy.

During the diagnostic process, all classification features of thyroid insufficiency are established, which simplifies the treatment process.

Primary congenital hypothyroidism

In 90% of cases, this disease is sporadic, and the remaining 10% are associated with hereditary factors. Studies indicate that thyroid gland formation disorders during intrauterine development are based on embryogenesis defects and other congenital defects.

The pathological condition can be caused by unfavorable environmental factors, various intoxications and infectious diseases of the pregnant woman up to the 6th week of gestation.

Primary congenital hypothyroidism has several forms, which differ in etiological factors:

1. Thyroid dysgenesis (hypoplasia, aplasia, ectopia) – in 57% of cases, ectopic location of the thyroid gland is observed in the sublingual region. In this form, the gland is formed not from the distal, but from the proximal end of the thyroglossal duct, which, with normal development of the body, atrophies at the 8th week of intrauterine development. In 33% of cases, aplasia and hypoplasia of the thyroid gland are diagnosed.
2. Dyshormonogenesis – the organ has a normal location, but its size is slightly enlarged. There are disturbances in the synthesis, peripheral metabolism and secretion of thyroid hormones.

The mechanism of development of these forms has not been thoroughly studied. Medicine knows cases of familial aplasia (athyrosis) and ectopic localization of the thyroid gland. It has also been established that gene mutations associated with hormonogenesis disorders are transmitted only by an autosomal recessive type.

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Congenital hypothyroidism with diffuse goiter

A disease caused by partial or complete deficiency of thyroid hormones is congenital hypothyroidism. Diffuse goiter is one of the complications of this pathology. Goiter is a painless but noticeable enlargement of the thyroid gland. Most often, the enlargement is diffuse, but nodular enlargement is also encountered.

Not all newborns have a goiter, but as the child grows, it can manifest itself, causing compression of the trachea, disruption of the breathing and swallowing process. The following types of the disease are distinguished:

1. Parenchymatous goiter is a structural change in the thyroid tissue, the growth of the organ is associated with an increase in its epithelial layer. The outer tissues are a dense formation of pink-gray color, accompanied by the following symptoms:

• Bulging eyes.
• Increased sweating and cold skin.
• The baby is restless, cries frequently and has a hoarse voice.
• Problems with stool (constipation, upset stomach).
• Poor weight gain.

2. Nontoxic congenital goiter is diagnosed in newborns and infants. It is characterized by pronounced thyrotoxicosis. Goiter is present at birth or appears in the first months of life. There are no antithyroid antibodies in the child's blood, there is a violation of the synthesis of thyroid hormones.

Both forms of the disease are characterized by a marked decrease in mental activity, cardiovascular disorders, and intestinal problems. Symptoms develop slowly. Treatment consists of replacement therapy, i.e. taking hormonal drugs. Therapy is lifelong with annual testing.

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