Hypothyroidism in Infants
Hypothyroidism in newborn babies is also known as congenital hypothyroidism and occurs in less that 0.01% of infants. In almost 90% of the cases, the patient suffers from hypothyroidism all his life. The process of development of the thyroid, pituitary and the hypothalamus as well as the mechanism by which hormones are produced is quite complex and any abnormality during these processes can result in congenital hypothyroidism.
Hypothyroidism in Infants
Congenital deficiency of the thyroid hormones causes cretinism in infancy. Cretinism due to congenital hypothyroidism may occur in endemic or sporadic forms. Endemic cretinism is found in areas of severe iodine deficiency and in most cases, the mother of the affected child has a goiter. Sporadic cretinism is rare and is due to congenital absence of thyroid tissue or failure of the embryonic gland to descend into the neck. Thyroid deficiency may also be caused by a partial or complete absence of one of the several enzymes required for the bio-synthesis of the thyroid hormones. In rare cases, cretinism due to congenital hypothyroidism is associated with goiter and is often an inherited familial disorder. Sporadic cretinism can also occur in an infant whose mother is hyperthyroid and who has been treated with large doses of antithyroid drugs during her pregnancy. These antithyroid drugs cross the placenta and depress thyroid function in the fetus, leading to congenital hypothyroidism.
The infant is lethargic, may fall asleep during feeding, fails to thrive and is constipated. The physical signs of congenital hypothyroidism may not appear till the second month. The child's abdomen is prominent and an umbilical hernia is often present. The face is broad and puffy with a flat nose and thickened lips and nostrils.The infant suffering from congenital hypothyroidism has an enlarged tongue that protrudes from the mouth and the child's skin is thickened, dry to the touch, pale and waxen. The infant's temperature may be below normal, its hair is often dark and the eyes are wide-set. The infant's voice when crying tends to be hoarse and the child may be mentally retarded.
The occurrence of cretinism in congenital hypothyroidism can be prevented by prophylactic administration of iodide to the mother during pregnancy, especially in areas where goiter is endemic. To avoid mental deficiency, cretinism must be recognized and treated early. However, when congenital hypothyroidism has been marked in fetal life, the changes may be irreversible.
