Hypothyroidism screening in newborns

Legally prescribed diagnostic procedures for the early detection of congenital hypothyroidism.

Only the introduction of neonatal screening in the 1970s made the preclinical biochemical diagnosis of congenital hypothyroidism possible. Since then, severe cerebral damage in affected children can be completely avoided by starting substitution therapy in the first week of life. Thus, the newborn screening for congenital hypothyroidism is one of the most successful and cost-efficient secondary prevention programs in medicine, taking into account all economic costs of lifelong mental retardation.

A, 3rd day of life, 1-2 drops of blood from the heel are placed on filter paper: TSH determination. In congenital hypothreosis: basal TSH increased.

Confirmatory diagnosis: venous confirmatory diagnosis includes TSH, fT3, fT4, thyroglobulin and, in case of anamnestic evidence, search for maternal thyroid autoantibodies or iodine deficiency.

Since during and after birth the thyroid-stimulating hormone, TSH, physiologically increases to values of 100 mU/L and slowly normalizes over the next few days, neonatal screening is not performed until the 3rd day of life. However, a pathological screening test is not yet proof of congenital hypothyroidism. In case of slightly elevated, not reliably pathological TSH values, a second control is required. In the case of clearly pathological TSH values, immediate therapy must be initiated.

However, the excellent sensitivity of TSH-based screening is limited to primary hypothyroidism. In normal neonatal screening the rare central hypothyroidism (lack of TSH increase) cannot be excluded. If clinical suspicion exists, a venous determination of TSH and fT4, fT3 must be performed in these cases.