Increasing supplemental thyroid hormone use among premature infants born at 23 to 32 weeks' gestation

Abstract

We assessed the pattern of levo-thyroxine (l-thyroxine) therapy in very premature newborns over a 10-year period. We analyzed the electronic database of a large private neonatal practice group (Pediatrix, Ft. Lauderdale, FL) for 23- to 32-week gestation neonates ( N = 96,813) managed during 1997 to 2006. L-thyroxine use was analyzed by birth year and by gestational age (GA). L-thyroxine use increased with decreasing GA (nadir 0.3% at 32 weeks, peak 8.4% at 24 weeks). L-thyroxine supplementation increased 2.6-fold over time among infants ≤26 weeks' GA (3.4% in 1997 to 1999 to 8.7% in 2004 to 2006), but did not change among infants born at ≥29 weeks' GA. The highest rate of l-thyroxine supplementation (12.8%) occurred among 24-week GA infants in 2006. Median age at start of l-thyroxine was 23 days (25 to 75%, 15 to 38 days). Only 2% of treated infants were started on day of life 1. Despite no clear evidence from randomized trials supporting thyroid supplementation, l-thyroxine treatment of very preterm infants has significantly increased over the past decade. As l-thyroxine treatment was not consistent with protocols from published randomized trials, new focused randomized controlled trials are needed.