Abstract
Congenital hypothyroidism (CH) is one of the most common causes of preventable mental retardation. Thyroid hormone has an essential role in the brain development during the first 2-3 years of life. Incidence of CH is 1:3000-1:4000 live births, but there is evidence that its incidence is increasing. Majority of newborn babies do not exhibit obvious clinical signs and symptoms until the age of 3 months due to either some residual thyroid function or transplacental passage of maternal thyroid hormone. Common clinical symptoms include lethargy, sleepiness, poor feeding, constipation, and prolonged jaundice. Other common findings on clinical examination include macroglossia, large fontanels, umbilical hernia, and hypotonia. Neonatal screening for CH is practiced in the developed countries for the last three decades, and various studies show that normal cognitive function is attainable with early detection and treatment. This review discusses different protocols being used for screening. It highlights recent recommendation of screening and retesting cutoffs. Thyroid imaging can help in differentiating underlying etiology, either thyroid dysgenesis or dyshormonogenesis. Treatment with levothyroxine (L-T4) 10-15 mcg/kg should be started immediately after diagnosis without delaying for imaging purposes. Frequent and vigilant monitoring with L-T4 dose adjustment is mandatory in infancy and childhood to achieve normal physical growth and neurodevelopment. Children with CH are followed by different pediatric specialties including general pediatricians, neonatologists, developmental pediatricians, and endocrinologists and in primary care; therefore, it is essential to increase the awareness of monitoring protocols among all physicians.