Neonatal thyroid screening: methods-efficiency-failures.

Newborn screening for congenital hypothyroidism (CH) is one of the major achievements of preventive medicine, as the condition occurs frequently (1/4000 newborns) and results in brain damage if not detected and treated in the first few days of life. Measurement of T4 and/or TSH in dried blood spots collected on the second through fifth days of life are the most widely used methods in screening programs for CH currently. Some children with the disease may be missd in any screening program, however, owing to factors related to the disease itself and the methods employed in its detection, as well as factors ascribed to the element of human error, ie screening errors. The methods employed in newborn screening programs for CH, their efficiency in disease detecetion, and biological factors as well as screening errors leading to missed cases are discussed.