Biomedical Research 2011; 22

Iodine deficiency is the most common cause of hypothyroidism worldwide but in areas of Iodine sufficiency, other causes including autoimmunity and iatrogenic factors are more common. During pregnancy, autoimmune thyroid disease, characterized by presence of specific thyroid auto antibodies, is mostly responsible for hypothyroidism. Such females, who often had previous history of repeated abortions, have infants with transient mild elevation of serum TSH above normal reference value for age in initial months of life. This type of transient congenital hypothyroidism, caused by maternal-fetal transfer of TSH-R blocking antibodies, is a rare condition. Here we present a case of newborn with known hypothyroid mother, whose TSH level was found to be raised at age of 1 day and goes back to within the normal range at the age of 17 days without taking treatment.