Hypothyroidism in children

Hypothyroidism is a clinical syndrome caused by a decreased production of thyroid hormones or a lack of sensitivity to them in tissues.

Hypothyroidism is a deficit of thyroid hormones. Symptoms of hypothyroidism in young children include eating disorders and physical retardation. Signs in older children and adolescents are similar to those of adults, but also include low physical development, later puberty or a combination of both. Diagnosis of hypothyroidism is performed on the basis of thyroid function research (for example, thyroxine level , thyroid-stimulating hormone in blood serum). Treatment of hypothyroidism includes replacement therapy with thyroid hormones.

Hypothyroidism in infants and young children can be congenital or neonatal. Congenital hypothyroidism occurs in approximately 1 child per 4,000 live births. Most congenital cases are sporadic, but approximately 10-20% are hereditary. The most common cause of congenital hypothyroidism is dysgenesis or absence (agenesis), or hypoplasia (hypoplasia) of the thyroid gland. Approximately 10% of congenital hypothyroidism is a consequence of dyshormonism (abnormal production of thyroid hormones), which can be of 4 types. Rarely in the US, but often in some developing countries, hypothyroidism is a consequence of iodine deficiency in the mother. Rarely transient hypothyroidism can be caused by transplacental intake of antibodies, zybogenic substances (eg, amiodarone) or thyreostatic drugs (eg, propylthiouracil, methimazole).

ICD-10 code

• E00 Syndrome of congenital iodine deficiency.
• E01.0 Diffuse (endemic) goiter associated with iodine deficiency.
• E01.1 Multinodular (endemic) goiter associated with iodine deficiency.
• E01.2 Goiter (endemic), associated with iodine deficiency, unspecified.
• E01.8 Other thyroid disorders associated with iodine deficiency and similar conditions.
• E02 Subclinical hypothyroidism due to iodine deficiency.
• E03.0 Congenital hypothyroidism with diffuse goiter.
• E03.1 Congenital hypothyroidism without goiter.
• E03.2 Hypothyroidism caused by medications and other exogenous substances.
• E03. 3 Postinfectious hypothyroidism.
• E03.5 Myxedema coma.
• E03.8 Other specified hypothyroidism.
• E03.9 Hypothyroidism, unspecified.

Hypothyroidism in older children and adolescents

Usually the cause is autoimmune thyroiditis (Hashimoto's thyroiditis). Some symptoms of hypothyroidism are similar to those of adults (eg, weight gain, obesity, constipation, rough, dry hair, yellowish, cold or marbled rough skin). Signs specific to children include delayed physical development, late maturation of the skeleton, and usually delayed puberty. Treatment is carried out with L-thyroxine at a dose of 5-6 μg / kg orally once a day; in adolescents, the dose is reduced to 2-3 μg / kg orally once a day and titrated to maintain the level of thyroxine and thyroid-stimulating hormone in the serum at normal age limits.

Symptoms of hypothyroidism in children

Symptoms of hypothyroidism differ from those of adults. If iodine deficiency occurs early in pregnancy, the child may develop endemic cretinism (a syndrome that includes deaf mute), mental retardation and muscle spasticity. In most cases, infants with hypothyroidism have few manifestations, or they are generally absent, because the placenta receives thyroid hormones from the mother. However, after maternal hormones are metabolized, if the underlying cause of hypothyroidism is maintained, and if hypothyroidism is not diagnosed and treatment is not performed, moderate or severe retardation of the development of the central nervous system occurs, which may be accompanied by muscle hypotension, prolonged hyperbilirubinemia, umbilical hernia, respiratory failure, macroglossia, large fontanel sizes, hypotrophy and hoarse voice. Rarely, late diagnosis and treatment of severe hypothyroidism lead to mental retardation and stunting.

Classification of hypothyroidism

Allocate congenital and acquired hypothyroidism; the level of disturbance of regulatory mechanisms distinguishes primary (pathology of the thyroid gland itself), secondary (hypophysial disorders) and tertiary (hypothalamic disorders). There is also a peripheral form of hypothyroidism associated with a disruption in the metabolism of thyroid hormones in tissues or the resistance of tissues to them.

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Diagnosis of hypothyroidism in children

Routine screening of newborns reveals hypothyroidism before clinical manifestations become apparent. Upon obtaining a positive result of the screening examination, a study of the thyroid function, including thyroxine (T3), free T4 and thyroid-stimulating hormone (TSH) in the blood serum is shown.

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Treatment of hypothyroidism in children

In most cases, lifelong replacement therapy with thyroid hormones is required. Treatment of hypothyroidism in children with L-thyroxin 10-15 μg / kg orally once a day should be started immediately and regularly monitored at short intervals. This dose is intended for the rapid normalization of serum T levels, after which it should be corrected to maintain a serum T level within 10-15 μg / dl during the first years of life. In the second year of life, the usual dose is 5-6 μg / kg orally once a day, which should maintain serum T and TSH levels within normal age limits. The majority of children receiving treatment for motor and mental development are normal. Severe congenital hypothyroidism in children, even with adequate treatment, can still lead to small developmental problems, as well as neurosensory hearing loss. Hearing impairment can be so insignificant that the initial screening may not reveal it. It is recommended to conduct a second examination in 1-2 years to identify hidden hearing defects that can affect the development of speech. The deficiency of thyroxin-binding globulin, which is found in a screening study based primarily on the definition of thyroxine, does not require treatment, since in this case, children have euthyroidism.