Optimal Timing of Repeat Newborn Screening for Congenital Hypothyroidism in Preterm Infants to Detect Delayed Thyroid-Stimulating Hormone Elevation.

Objectives: To evaluate the timing of a delayed rise in thyroid-stimulating hormone (TSH) levels in preterm infants with congenital hypothyroidism, and to determine whether cases of congenital hypothyroidism would be missed by using current consensus guidelines of repeat screening at approximately 2 weeks of age or 2 weeks after the first screening.

Study Design: The study was performed over a 13-year period (January 2004-December 2016). Whole-blood TSH samples were collected between 72 and 120 hours after birth.