Neonatal thyroxine supplementation in very preterm children: developmental outcome evaluated at early school age.
OBJECTIVE
Transient hypothyroxinemia in very premature infants is associated with developmental problems. A randomized, placebo-controlled trial of thyroxine (T(4)) supplementation was conducted in a group of 200 infants <30 weeks' gestation. T(4) supplementation improved mental outcome at 2 years old in children of 25/26 weeks' gestation only. The effect of T(4) supplementation beyond 2 years of age is unknown. We present the effects of neonatal T(4) supplementation on outcome at early school age.


METHODS
Standardized measurements were used to assess cognitive, behavioral, and motor outcome, as well as a qualitative assessment of neurologic functioning. Survivors of the T(4) trial were assessed at the age of 5.7 years.


RESULTS
Ninety-nine percent of the 157 survivors participated. Outcome on all domains was comparable between the T(4) group and placebo group. In children <27 weeks' gestation, a 10 IQ point difference was found in favor of the T(4) group, whereas in children of 29 weeks' gestation, a difference of 15 IQ points was found in favor of the placebo group. Teachers' reports showed less behavioral problems in the T(4)-treated children of 25/26 weeks' gestation, but more behavioral problems in the T(4)-treated children of 27 weeks' gestation. Differences in motor outcome and neurologic outcome were in favor of the T(4)-treated children <29 weeks' gestation, but not of the T(4)-treated children of 29 weeks' gestation.


CONCLUSIONS
We found benefits of T(4) supplementation for children <29 weeks' gestation, and especially in children of 25/26 weeks' gestation. However, in children of 29 weeks' gestation T(4) supplementation is associated with more developmental problems.
Briët
J M
JM
Department of Neonatology, University of Amsterdam, Amsterdam, The Netherlands. j.m.briet@amc.uva.nl
van Wassenaer
A G
AG
Dekker
F W
FW
de Vijlder
J J
JJ
van Baar
A
A
Kok
J H
JH
D002648:Child; D002657:Child Development / Q000187:drug effects / Q000502:physiology*; D002675:Child, Preschool; D002658:Developmental Disabilities / Q000175:diagnosis / Q000517:prevention & control; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D007037:Hypothyroidism / Q000175:diagnosis / Q000517:prevention & control; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood / Q000254:growth & development*; D009483:Neuropsychological Tests; D013974:Thyroxine / Q000008:administration & dosage* / Q000097:blood / Q000627:therapeutic use; D016896:Treatment Outcome
D013974:Thyroxine