Distinctive features of congenital hypothyroidism, its causes and treatment

Normally, the thyroid gland secretes 3 major hormones:

• triiodothyronine( T3),
• tetraiodothyronine( thyroxine, T4),
• calcitonin.

A pathological condition in which there is a shortage of thyroid hormones since birth - congenital hypothyroidism.

Etiology

Congenital thyroid insufficiency can be caused by various causes that can be conditionally divided into several groups:

1. Morphofunctional immaturity of the gland, its underdevelopment or total absence. This condition is most often found when the pregnant teratogenic factors influence the body:
   • infection,
   • radiation,
   • chemical,
   • some medicinal substances.
2. Congenital immaturity of the hypothalamic-pituitary system. In this case, the thyroid gland can be completely healthy, but due to insufficient release of releasing and tropic hormones, the level of thyroid hormones will also be low.
3. Congenital hypothyroidism of an autoimmune nature. The thyroid gland of the fetus is considered immune to the mother, as a foreign tissue and is attacked by antibodies. Genetically determined defects of the hormone T4.
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4. Inadequate intake of iodine during pregnancy. Most often observed in areas of iodine endemia.

Pathogenesis of

Fetus, in which the thyroid gland does not release enough hormones, compensates for this condition with the help of maternal hormones that enter through the placenta. But after giving birth, he is deprived of this source and their level drops sharply.

Thyroid hormones, in particular T3 and T4, are one of the key elements in the ripening process of the cerebral cortex, as well as the myelination of nerve fibers.

Therefore, with congenital hypothyroidism develops mental underdevelopment of the child - cretinism. The lack of another hormone - calcitonin - leads to underdevelopment of bone and cartilage tissue, as well as other organs.

Clinical picture of

Classical symptoms of congenital hypothyroidism are quite specific, but are observed only in 10-15% of all cases, which significantly complicates early diagnosis of the disease. The most common signs in the early neonatal period are:

• high birth weight( 4000-4500 g) at delivery in the
• period low, rough cry
• edematous face, half-open mouth with extended wide tongue
• umbilical hernia and later retraction of umbilical cord with subsequent badwound healing
• later departure of meconium

If the disease remains unrecognized and adequate therapy is not prescribed, then by the age of 5-6 the symptoms of congenital hypothyroidism in children are manifested in the classical triad: forerzhka physical and mental development, impaired trophism skin and its appendages, functional disturbances in other systems and organs.

In the future, the child is noted later teething, violation of body proportions, chondrodystrophy, frequent fractures, underdevelopment of the facial skeleton. Physical examination reveals cardiac dullness, bradycardia, low blood pressure, cardiomegaly, etc.

Diagnosis

The diagnosis of congenital hypothyroidism is based on a characteristic clinical picture and laboratory diagnosis - the determination of the level of thyroid hormones in the blood. If it is known that a woman lives in an endemic area, then prenatal diagnosis of thyroid insufficiency is possible-the determination of the level of hormones in the umbilical blood.

An additional method of investigation is ultrasound diagnosis, which allows to judge the degree of maturity of the gland.

For the purpose of mass diagnostics and prevention of irreversible changes in the central nervous system, a massive screening of all newborns is now under way, for 4-5 days of life. To do this, the blood of the baby, which is usually taken from the heel, determines the level of thyroid-stimulating hormone( TSH) secreted by the pituitary gland. The low level of this hormone, in comparison with the age norm, allows to suspect the child of congenital hypothyroidism.

Treatment of

The main goal of the treatment is to provide the necessary level of thyroid hormones for normal functioning, with the help of substitution therapy, which is carried out for life. Treatment of congenital hypothyroidism carried out in 2 stages:

1. Achieving euthyroid state - the balance between the body's need for thyroid hormones and their concentration
2. Maintaining compensatory state without disease progression.

Given the vital need for thyroid hormones, treatment with substitution therapy should be prescribed as soon as possible. Clinically, it is possible to avoid irreversible changes in the brain if treatment is started no later than 2 weeks after birth.

The main drug that is used for treatment is levothyroxine sodium. The dosage of the drug is selected individually, depending on the anatomical and physiological characteristics of the child, clinical and laboratory indicators. Through 1 , 5 weeks and 2 months after the initiation of therapy, blood test fetuses are performed to prevent overdose.

At the same time, special attention is paid not to TSH, but to T4, since the feedback principle, according to which the hypothalamic-pituitary system functions, may not yet be perfect in the first months of life.

Timely-initiated therapy and constant intake of drugs in the prescribed dose allow to completely compensate for congenital insufficiency of the thyroid gland and ensure the child a normal development.