ABSTRACT
Around the time of birth and during the first few years of life, thyroid hormone economy undergoes major changes that need to be understood for proper investigation and treatment of thyroid dysfunction. The dramatic consequences of congenital hypothyroidism (CH) that is not diagnosed during the neonatal period for later brain development underline the importance of prompt recognition of abnormal thyroid function test results (1). While congenital hyperthyroidism is a much less common and usually self-limited entity, it may also lead to dramatic consequences; indeed, heart failure and even death from this condition have been reported in hyperthyroid fetuses and newborns, and later developmental problems may occur as well (2).
