Hypothyroidism is a disease caused by a decreased production of thyroid hormones of the thyroid gland and their insufficient content in the blood. In childhood, hypothyroidism is more common than other thyroid disorders. Girls get sick more often than boys. Distinguish between congenital and acquired hypothyroidism.
Etiology of hypothyroidism
Congenital hypothyroidism develops in the prenatal period due to hypoplasia or aplasia of the thyroid gland of the fetus and a sharp decrease in the volume of its functioning tissue. K. this can lead to various harmful factors that say an adverse effect on a woman during pregnancy (eating and diet, toxic-infectious conditions, etc.). Congenital hypothyroidism can develop due to hereditary defects in the biosynthesis of thyroid hormones at various levels of conversion of their predecessors. Thyroid function is also impaired due to intrauterine damage.
Acquired primary hypothyroidism can occur with infectious and inflammatory lesions of the thyroid gland (thyroiditis), injuries of it, subtotal strumectomy, as well as in the treatment of thyrostatic drugs with diffuse toxic goiter. The development of secondary hypothyroidism is possible with damage to the hypothalamic-pituitary region (tumors, etc.). There are cases of hypothyroidism due to a lack of iodine in the body.
The pathogenesis of hypothyroidism
The basis of the pathogenesis of hypothyroidism is a decrease in the mass of the glandular tissue of the thyroid gland and insufficient production of thyroid hormones. The autoimmune factor is of great importance in the genesis of acquired hypothyroidism. Thyroglobulins, which enter the blood stream after a stumectomy, are antigens. A response to the presence of thyrogenic proteins in the blood is an increase in the titer of autoantibodies. Autoimmune processes are played out in the tissue of the thyroid gland and lead to destructive changes in its parenchyma and a decrease in functional activity. The development of secondary hypothyroidism is due to a violation of the synthesis of thyrotropin, or thyrotropin-releasing hormone and insufficient intake of thyroid hormones in the thyroid gland. As a result of deficiency of thyroid hormones, disorders of all types of metabolism and changes in tissues and organs occur. The growth retardation of patients is associated with a decrease in oxidative processes and impaired protein synthesis, the development of mucosal edema is caused by the retention of water and sodium chloride, the accumulation of mucoproteins in the connective tissue, etc.
Pathomorphology of hypothyroidism
Atrophy of glandular tissue, proliferation of connective tissue (thyroiditis) is noted. Signs of thyroid underdevelopment are characteristic of congenital hypothyroidism. Sometimes – hyperplasia and hypertrophy of the gland (with genetically caused lesions).
Classification of hypothyroidism
There are congenital (myxedema) and acquired ppthyroidism, primary and secondary; with the course – mild, moderate and severe forms of the disease.
Clinic of hypothyroidism
The clinic of congenital and acquired hypothyroidism is characterized by a wide variety of symptoms. Body weight in children with congenital hypothyroidism at birth is more than usual, slow umbilical cord rejection and persistent constipation are often noted. At the age of the first six months, one can already notice a lag in physical and mental development. In such children, the development of facial bones is slowed down, the teeth appear very late and are randomly located, the nose is saddle-shaped, the face is puffy, the tongue is stuck out of the mouth, and there is constant salivation. A dull facial expression is noteworthy. A round face and small eyes, lips are thick, voice is rough, hoarse. The neck is short. The skin is pale with a grayish tint, rough, dry, peeling easily. Hair on the head is sparse, thickened, grow slowly. The nails are brittle. The subcutaneous tissue is swollen or pasty, in the supraclavicular fossa and on the back surfaces of the hands there is an accumulation of fat in the form of “pads”. The growth of a child of 9-11 years old can correspond to the growth of a 3-4 year old child. Hands are short, fingers are dull, the brush resembles a paw. The abdomen is bulging, an umbilical hernia is often observed. Children are sluggish, do not show interest in the environment, the gaze is fixed, the expression of the eyes is indifferent. If the disease started in the early period, insufficient brain development with degenerative changes in nerve cells and a sharp delay in mental development, up to complete dementia, are characteristic. From the side of the cardiovascular system – expansion of the borders of the heart, deafness of tones, bradycardia. On the ECG – low voltage of all the teeth, especially the QRS complex, an increase in the time of intraventricular conduction. Radiologically – the absence of ossification nuclei in the pelvic and femur in children of the first year of life and their late appearance in older children. This is the basis of the violation of the processes of ossification. Hypothyroidism in children is accompanied by a reduced content of nitrogen, creatinine, calcium, phosphorus and iodine in the urine; elevated serum creatinine and cholesterol, hypoalbuminemia and hyperglobulinemia. The main metabolism is reduced to 25 – 35%. On the part of the blood – moderate anemia of the hypochromic type, neutropenia, eosinophilia, monocytosis. The content of protein-bound iodine (SBI) and butanol-extracted iodine (15EU) is reduced; the thyroid absorption curve of 131J decreases sharply; with autoimmune forms, the titer of antibodies to thyroglobulin increases . Such a clinic is characteristic of severe hypothyroidism. With a mild form, the symptoms of hypothyroidism are less pronounced.