Evaluation of the effect of thyroxine supplementation on behavioural outcome in very preterm infants

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.