Hypothyroidism in Newborns: Diseases of the Thyroid Gland in Children

Hypothyroidism is a disease in which the function of the thyroid gland is reduced or completely absent. Congenital hypothyroidism, according to different authors, occurs in 1: 3000-1: 6000 newborns. Distinguish between primary hypothyroidism, when the structure of the thyroid gland is damaged (hypoplasia, aplasia, abnormal location); secondary, when TSH secretion is impaired, and tertiary – with impaired synthesis of thyroluberine in the hypothalamus. Hypothyroidism in newborns is in most cases congenital. It can be caused by a malformation of the thyroid gland, genetic defects in enzymes involved in the synthesis of hormones, insufficient intake of iodine in the fetus, thyroid diseases in the mother during pregnancy or shortly before its onset.

All types of metabolism are impaired in children with congenital hypothyroidism. Inhibition of protein synthesis leads to an increase in serum albumin and a decrease in globulin fractions, anemia and an increase in ESR. Disturbed carbohydrate metabolism with the development of hypoglycemia, deposition of mucopolysaccharides in tissues. There is a violation of water-salt metabolism with the transition of sodium salts into the intercellular space (“symptom of antidiuresis”). A decrease in the activity of the glucuronyl transferase system is accompanied by a violation of the conjugating ability of the liver.

 

Hypothyroidism leads to a delay in physical and especially mental development, so early diagnosis of the disease is of great importance. At the same time, the clinical symptoms of hypothyroidism in the neonatal period may be non-specific and occur in other diseases. Children with congenital hypothyroidism are often born with a large body weight, often postponed. Early symptoms of the disease include general lethargy, weakness in sucking, hypothermia up to 35 ° and below, muscle hypotonia, decreased physiological reflexes, pastiness or edema syndrome. Some people observe acrocyanosis, attacks of cyanosis, SDS, bloating, prolonged passage of meconium. In typical cases, the appearance of the child is quite characteristic (puffy face, narrow eye slits, hypertelorism, wide open sutures and fontanelles of the skull, sunken nose, often a large tongue, a posture of weak flexion, a tendency to bradycardia). More than half of children with hypothyroidism have jaundice, which is most important for early recognition of the disease. Jaundice can be noted at birth. It is often pronounced, with a high level of free and bound bilirubin in the blood, without signs of liver damage, discoloration of urine and stools.

When observing children in dynamics, attention is drawn to the difficulties of feeding them due to drowsiness, respiratory disorders (attacks of cyanosis, difficulty in nasal breathing), insufficient weight gain, and late loss of the umbilical cord. In some babies, despite weak suckling and insufficient milk supply, weight gain may be normal. As hypothyroidism progresses, the classic symptoms develop: muscle hypotension, enlarged abdomen, umbilical hernia, hernia of the white line of the abdomen, dry flaky integuments, sparse, dull hair, puffy face, large tongue, myxedema pillows in the supraclavicular region, hypothermia, bradycardia, persistent constipation.

In a laboratory study of newborns with hypothyroidism, anemia, an increase in ESR, dysproteinemia with an increase in the albumin fraction, hypercholesterolemia, hyperlipemia, hypoglycemia can be detected. On radiographs of the bones of the skeleton, a violation of the maturation of the ossification nuclei is noted. The determination of total T4 and especially the amount of TSH is of great diagnostic value. In recent years, great importance has been attached to a mass screening test for congenital hypothyroidism, carried out on the 3rd-6th day of a newborn’s life. T4 and TSH are determined by the dry drop method in the blood of a newborn. Determination of T 4 content onlyoften gives false positive results, so most authors prefer the definition of TSH. Newborns with elevated TSH levels (25–100 mcg / L) should be carefully screened for congenital hypothyroidism. Early diagnosis and timely therapy contribute to the normal physical and mental development of the child.

Treatment of congenital hypothyroidism is the administration of thyroid hormones. The dose of thyroid hormones depends on the degree of thyroid insufficiency. Thyroidin, thyrocomb, T 3 can be used as replacement therapy… The dose of the drug is selected individually under the control of the general condition, pulse, body weight, child’s stool, ECG, determination of blood cholesterol. They also recommend drugs that improve the trophism of the nervous system (gammalon, aminalon, cerebrolysin, glutamic acid). Our experience allows us to recommend, before consulting an endocrinologist, if hypothyroidism is suspected, to prescribe a newborn thyroidin at a dose of 5-10 mg per day with an increase in dose every 5 days under the control of the general condition, pulse rate, and the amount of cholesterol in the blood. A patient with hypothyroidism should be under dispensary supervision to monitor the adequacy of hormone replacement therapy.

Hyperthyroidism is extremely rare in newborns. When a pregnant woman becomes ill with hyperthyroidism, pathological immunoglobulin ( LATS ) appears in her blood , which causes a long-term increase in the activity of the thyroid gland. Immunoglobulin crosses the placenta. In a newborn, in these cases, goiter and typical signs of hyperthyroidism are determined: exophthalmos, motor restlessness and poor physical development. LATSit collapses within 2-3 weeks and the symptoms of the disease gradually disappear without treatment. In severe cases (asphyxia due to compression of the trachea), immediate surgery is indicated. Conservative treatment consists of sedating and caring for the child. Iodine and thyreostatics should be prescribed only in severe disease. As LATS is cleared, there is sustained improvement.