Abstract. Hyperthyroidism is a pathological condition in which the level of thyroid hormones in the blood is increased. These biologically active substances ensure the regulation of metabolic processes and the maturation of the organism, as well as the functioning of most organs and tissues. Symptoms of hyperthyroidism often appear in adolescents, girls are affected more often than boys. Prepubertal children are somewhat less affected, and infants are rarely affected. In the second case, excess thyroid hormones are associated with the presence of toxic goiter in the mother. Its antibodies, which penetrate the placenta, circulate in the blood of the fetus and stimulate the overproduction of thyroid hormones.