Symptoms and forms of congenital hypothyroidism

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

[1], [2], [3], [4]

Symptoms

The main symptoms of congenital hypothyroidism include:

• Prematurity (childbirth up to 38 weeks of gestation).
• Worn baby
• The delay in the discharge of meconium.
• The weight of a newborn is more than 4 kg.
• Prolonged physiological jaundice.
• Apnea during feeding.
• Muscle atony.
• Flatulence, a tendency to constipation and frequent regurgitation.
• Gyoporeflexia.
• Increased size of tongue and fontanelles.
• Apathetic.
• Dysplasia of the hip joints.
• The coldness of the skin.
• Swelling of the limbs and genitals.
• A gruff and low-set voice when weeping.
• Long and difficult healing of the navel, hernia.

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

• The skin is dry and compacted.
• Cloth jaundice gray.
• Myxedema (edema of the subcutaneous tissue and skin).
• Sweat removal is reduced.
• Hair and nails are atrophied.
• The voice is rough, hoarse and low.
• Delayed psychomotor development.

The symptomatology of the central forms of congenital hypothyroidism, that is, secondary and tertiary, is not clearly expressed. The disease occurs with a deficiency of other hormones (somatotropic, luteinizing, follicle-stimulating) and abnormalities in the structure of the facial skull.

Without timely treatment, acute thyroid hormone deficiency causes irreversible effects in neuropsychic development. In newborns, there is a significant lag in physical and mental development, that is, cretinism. The main symptoms of this complication include: short stature, facial abnormalities, abnormal limb development, chronic diseases, and frequent colds.

Congenital hypothyroidism in children

The main cause of congenital abnormalities of the thyroid gland is an autoimmune reaction. Autoimmune thyroiditis  is a condition in which the immune system gradually destroys the thyroid gland. This is 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  congenital hypothyroidism :

• Chromosomal diseases: Down syndrome, Williams syndrome, Shereshevsky syndrome.
• Autoimmune pathologies: diabetes mellitus, celiac disease.
• Injuries to the thyroid gland.

The disease may be asymptomatic or accompanied by such 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 during the first few days, all babies are checked for serious pathologies. To do this, a blood test from the heel of the baby. Blood is checked for the amount of thyroid hormones in order to determine how well it works.

Symptoms of the disease become more pronounced when the child’s age reaches 3-6 months:

• Slow growth.
• Lag in neuropsychic development.
• Disproportionate physique.
• Mucinous swelling of the eyelids.
• Thick lips, tongue and nostrils.
• Umbilical hernia.
• Deaf heart sounds and bradycardia.
• The thyroid gland is enlarged or poorly palpated.

When violations are detected, the doctor makes a course of treatment. The child is prescribed daily intake of synthetic hormones. In some cases, the body begins to work independently, if this does not happen, then 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 medication continued until full puberty. If you leave the pathology without treatment, it threatens with serious complications.

[5]

Congenital hypothyroidism in newborns

Medical statistics indicate that in 75-90% of cases, abnormalities in the functioning of the thyroid in newborns occur due to malformations of the organ. The weight of a baby's thyroid gland is about 2 g. Aplasia or hypoplasia forms during the prenatal period, at about 4–9 weeks of gestation. By the end of the first trimester, the fetus thyroid accumulates iodine and synthesizes thyroid hormones.

The main causes of genetic disorders are:

• Viral diseases of the mother during gestation.
• Toxic effects of drugs or chemicals.
• Impact on the body of pregnant radioactive iodine.
• Disorders of the hypothalamic-pituitary system.

Transient hypothyroidism may be part of the adaptation of the organism to new living conditions or indicate a lack of iodine. The above reasons lead to a significant decrease in thyroid hormone levels, which entails a weakening of their biological effectiveness. This is indicated by a decrease in the growth of cells and tissues. Changes affect the central nervous system.

It is difficult to determine the disease in its early stages because it has many different symptoms that parents take for the physiological condition of the infant or signs of other diseases. The characteristic symptoms of the disorder are:

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

A complex of laboratory and instrumental studies is carried out to determine the disease. The diagnosis is confirmed if the TSH in the serum exceeds 20 μED / ml. It is mandatory to differentiate anomaly with birth injuries, rickets, jaundice, Down syndrome and other disorders. Treatment is long, in severe cases, surgery may be required.

[6]

Forms

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

By origin:

• Primary (thyroid) - pathological changes occur directly in the tissues of the organ.
• Secondary - occurs due to 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 species, as well as the secondary one, belongs to the central hypothyroidism.
• Peripheral - a violation or absence of receptors in tropic tissues, a failure in the conversion of thyroxin and triiodothyronine.

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

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

According to the effectiveness of treatment:

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

For the duration of congenital hypothyroidism is divided into:

• Transient - develops when exposed to maternal antibodies to the child's TSH, the duration from a week to 1 month.
• Permanent - lifelong replacement therapy.

In the process of diagnosis, all classification features of thyroid insufficiency are established, which simplifies the treatment process.

Primary congenital hypothyroidism

In 90% of cases, the disease is sporadic, and the remaining 10% is associated with hereditary factors. Studies have shown that impaired thyroid gland during fetal development is based on defects in embryogenesis and other congenital defects.

The pathological condition can be caused by adverse environmental factors, various intoxications and infectious diseases of a pregnant woman up to 6 weeks of gestation.

Primary congenital hypothyroidism  has several forms that differ in etiological factors:

1. Thyroid dysgenesis (hypoplasia, aplasia, ectopia) - in 57% there is an ectopic arrangement of the thyroid in the sublingual (hypoglossal) region. With this form of iron is formed not from the distal, but from the proximal end of the thyroid-lingual duct, which during normal development of the body atrophy at the 8th week of intrauterine development. In 33% of cases aplasia and thyroid hypoplasia are diagnosed.
2. Dyshormonogenesis - the body has a normal location, but its size is slightly increased. There are impaired synthesis, peripheral metabolism and secretion of thyroid hormones.

The mechanism of development of these forms has not been studied thoroughly. Cases of familial aplasia (athyrosis) and ectopic localization of the thyroid are known to medicine. It was also established that gene mutations associated with hormonogenesis disorders are transmitted only in an autosomal recessive manner.

[7], [8]

Congenital hypothyroidism with diffuse goiter

A disease caused by a 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 expansion has a diffuse form, but it also occurs nodular.

Not all newborns have goiter, but as the child grows up, it can manifest itself, causing compression of the trachea, impaired breathing and swallowing. These types of diseases are distinguished:

1. Parenchymal goiter is a structural change in the tissues of the thyroid gland, organ proliferation is associated with an increase in its epithelial layer. External tissue is a dense formation of pink-gray color, accompanied by the following symptoms:

• Protrusion of eyes.
• Increased sweating and cold skin.
• Anxiety baby, frequent crying and hoarse voice.
• Stomach problems (constipation, indigestion).
• Bad weight gain.

2. Nontoxic congenital goiter - diagnosed in newborns and infants. Characterized by severe 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 manifested by a pronounced decrease in mental activity, impaired cardiovascular system and intestinal problems. Symptoms develop slowly. Treatment consists of replacement therapy, that is, hormone therapy. Lifelong therapy with annual testing.

[9], [10]