Congenital hypothyroidism

• The most common congenital endocrine diseases (prevalence 1:3000–4000);
• Thyroid hormones have a key role in brain development, especially up to 8 months of age (a little less until 3 years of age);
• Without substitution therapy, irreversible brain damage occurs – with clinical diagnosis, the brain is already irreversibly damaged;
• Since 1985, a nationwide neonatal screening – determination of the level TSH;
• etiopathogenesis: in 75–80 % thyroid dysgenesis (agenesis, aplasia, hypoplasia, hemithyreoidea, cystic malformation, ectopia) or dyshormonogenesis (disorder of any stage of hormone synthesis or secretion; neonatal goiter), or rare Isolated congenital central hypothyroidism (congenital TSH defect – cannot be detected by neonatal screening);
• Clinical picture without treatment: initially only prolonged neonatal icterus (due to transplacental transmission of thyroid hormones from the mother), later (in the first 2-3 months of life) failure to thrive, delayed growth rate and bone maturation – late closure of fontanelles, delayed eruption of milk dentition, macroglossia, muscle hypotonia, omphalocele, constipation, hoarse crying, disorders of thermoregulation, anemia; even later growth disorder, psychomotor retardation, sensorineural hearing impairment;
• neonatal goiter or thyroid gland of normal size;
• 2–5 times increased risk of associated congenital malformations compared to the general population → ultrasound examination of the heart, kidneys and CNS is recommended;
• laboratory findings: ↑TSH, ↓fT₄; (for the central form ↓TSH i fT₄);
• therapy: lifelong replacement therapy with levothyroxine (started as soon as possible); intestinal absorption of L-thyroxine is aggravated by simultaneous ingestion of fiber, soy milk, calcium or iron preparations and malabsorption as such.

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