Primary sporadic congenital hypothyroidism (CH) is the most common cause of hypothyroidism infancy early childhood in iodine sufficient region. Screening for neonatal CH began in 1970s. The rationale and reason for neonatal screening for CH (NSCH) are well established. It is mandatory in most developed countries along with the screen for metabolic disorder. The possibility of measuring TSH and thyroid hormones in cord blood paved the way for newborn screening (NS) for CH. Worldwide it is estimated that 25% of the live born population of 130 million babies undergo NSCH. Klein et al., by 1972 had shown improved CNS prognosis in CH treated by age 3 months. NSCH has largely eradicated the severe irreversible neurodevelopmental damage and reversed the chances of growth failure in infancy and early childhood.