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Evaluation of the effect of thyroxine supplementation on behavioural outcome in very preterm infants
J M Briët1, A G van Wassenaer, A van Baar
1Department of Neonatology; Emma Children's Hospital, University of Amsterdam, The Netherlands.
Insights
Thyroxine administration in very preterm infants was linked to increased externalizing behaviors by age two. This effect was more significant in boys and those born earlier, suggesting a complex neurodevelopmental impact.
Area of Science:
- Neonatal Medicine
- Pediatric Neurology
- Developmental Psychology
Background:
- Very preterm infants (<30 weeks gestational age) face risks of neurodevelopmental challenges.
- Thyroid hormone plays a crucial role in brain development.
- Previous research on thyroxine supplementation in preterm infants has yielded mixed results regarding neurodevelopmental outcomes.
Purpose of the Study:
- To investigate the long-term behavioral effects of early thyroxine administration in very preterm children.
- To determine if thyroxine supplementation influences neurodevelopmental outcomes at two years of age.
- To explore potential factors moderating the relationship between thyroxine and behavior.
Main Methods:
- A randomized, double-blind, placebo-controlled trial involving 200 infants born before 30 weeks gestation.
- Infants received either a fixed dose of thyroxine (8 microg/kg/day) or placebo for the first six weeks of life.
- Behavioral outcomes were assessed at two years of age using standardized measures.
Main Results:
- Children treated with thyroxine exhibited more externalizing behaviors, particularly destructive behaviors, compared to the placebo group.
- This effect was more pronounced in male infants and those born at earlier gestations (≤27 weeks).
- Within the thyroxine group, children with behavioral problems had lower plasma-free thyroxine levels, suggesting the issues were not a direct result of overt hyperthyroidism.
Conclusions:
- Early thyroxine administration in very preterm infants may be associated with an increased risk of externalizing behavioral problems at two years.
- The findings highlight the need for careful consideration of thyroxine dosing and monitoring in this vulnerable population.
- Further research is warranted to elucidate the mechanisms underlying these behavioral changes and to optimize neurodevelopmental support for preterm infants.
Abstract:
Two-hundred infants of <30 weeks gestational age were included in a randomized double-blind controlled trial to study the effect of thyroxine administration on neurodevelopmental outcome in very preterm children. The infants were given either a fixed dose of thyroxine (8 microg/kg birthweight/day) or placebo for the first 6 weeks of life. This paper evaluates the effect of thyroxine administration on behavioural outcome at the age of 2 years. More externalizing, especially destructive, behaviours were found in the group given thyroxine than in the placebo group. This difference was more pronounced in boys and in children born after 27 weeks' gestation. The thyroxine-treated children with behavioural problems had lower plasma-free thyroxine levels than the thyroxine-treated children without behavioural problems. This finding suggests that the presence of more behavioural problems in the group given thyroxine was not an immediate consequence of the treatment.