Congenital hypothyroidism (CH) is a serious endocrine disorder in newborns caused by low levels of thyroid hormones (T4 and T3). Early signs are often subtle or absent, but untreated CH can lead to severe mental retardation and growth disturbances. With a global incidence of approximately 1 in 4,000 live births, early detection is critical. Neonatal T4 enables cost-effective, high-accuracy screening, allowing timely intervention with L-thyroxine therapy.