fifth month of pregnancy and after birth, depending on the type of process and its location in the brain, adequate levels of thyroid hormone are essential 4. The deleterious effects of lack of thyroid hormones during pregnancy can be avoided by transplacental transfer of hormones from mother to fetus 1,5 , however, from birth to maternal hormone transfer to the fetus disappears, and those newborns untreated after the third month of life usually present delayed physical and cognitive development, with the possibility of intellectual disability of varied grade 5. Already in the first three months of life, children with CH may present clinical signs of this metabolic alteration, such as lethargy, drowsiness, hypotonia, hypothermia, prolonged jaundice, edema, puffy eyes, large fontanelles, bloating, goiter, macroglossia, "facies syndrome", hoarse cry, nasal obstruction, difficulty breastfeeding, breathing difficulties, constipation, cold skin, pale, dry, scaly and carotenemia and umbilical hernia. After the third month, these signals become increasingly evident and delayed