Congenital Hypothyroidism: Screening and Management

Untreated congenital hypothyroidism (CH) leads to intellectual disabilities. Newborn screening (NBS) for CH should be performed in all infants. Prompt diagnosis by NBS leading to early and adequate treatment results in grossly normal neurocognitive outcomes in adulthood. However, NBS for hypothyroidism is not yet practiced in all countries globally. Seventy percent of neonates worldwide do not undergo NBS. The recommended initial treatment of CH is levothyroxine, 10 to 15 mcg/kg daily. The goals of treatment are to maintain consistent euthyroidism with normal thyroid-stimulating hormone and with free thyroxine in the upper half of the age-specific reference range during the first 3 years of life. Controversy remains regarding the detection of thyroid dysfunction and optimal management of special populations, including preterm or low-birth-weight infants and infants with transient or mild CH, trisomy 21, or central hypothyroidism. NBS alone is not sufficient to prevent adverse outcomes from CH in a pediatric population. In addition to NBS, the management of CH requires timely confirmation of the diagnosis, accurate interpretation of thyroid function testing, effective treatment, and consistent follow-up. Physicians need to consider hypothyroidism in the face of clinical symptoms, even if NBS thyroid test results are normal. When clinical symptoms and signs of hypothyroidism are present (such as large posterior fontanelle, large tongue, umbilical hernia, prolonged jaundice, constipation, lethargy, and/or hypothermia), measurement of serum thyroid-stimulating hormone and free thyroxine is indicated, regardless of NBS results.