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Effects of thyroxine supplementation on neurologic development in infants born at less than 30 weeks' gestation
A G van Wassenaer1, J H Kok, J J de Vijlder
1Department of Neonatology, Academic Medical Center, University of Amsterdam, the Netherlands.
Insights
Thyroxine supplementation for premature infants born before 30 weeks gestation did not improve overall developmental outcomes. This study found no significant differences in mental or psychomotor scores at 24 months corrected age.
Area of Science:
- Neonatal Medicine
- Developmental Pediatrics
- Endocrinology
Background:
- Transient hypothyroxinemia in premature infants may lead to developmental delays and neurologic dysfunction.
- The efficacy of thyroxine treatment during this critical period for improving developmental outcomes remains uncertain.
Purpose of the Study:
- To investigate the impact of thyroxine supplementation on neurodevelopmental outcomes in preterm infants.
- To determine if early thyroxine treatment improves cognitive and motor development in infants born before 30 weeks' gestation.
Main Methods:
- A randomized, placebo-controlled, double-blind trial involving 200 infants born at less than 30 weeks' gestation.
- Infants received either thyroxine (8 microg/kg/day) or placebo for six weeks, starting within 24 hours of birth.
- Developmental assessments (Bayley Scales) and neurologic function were evaluated at 6, 12, and 24 months corrected age.
Main Results:
- No significant differences in overall mental or psychomotor scores were observed between thyroxine and placebo groups at any assessment point.
- Mortality and morbidity were similar between groups up to hospital discharge.
- A subgroup analysis revealed a potential benefit in infants born <27 weeks gestation (higher MDI scores), but a detriment in those born >=27 weeks (lower MDI scores).
Conclusions:
- Thyroxine supplementation does not improve overall 24-month developmental outcomes in infants born before 30 weeks' gestation.
- The study suggests potential differential effects of thyroxine based on gestational age at birth, warranting further investigation.
Background:
Premature infants who have transient hypothyroxinemia in the first weeks of life may have developmental delay and neurologic dysfunction. Whether thyroxine treatment during this period results in improved developmental outcomes is not known.
Methods:
We carried out a randomized, placebo-controlled, double-blind trial of thyroxine supplementation in 200 infants born at less than 30 weeks' gestation. Thyroxine (8 microg per kilogram of birth weight) or placebo was administered daily, starting 12 to 24 hours after birth, for six weeks. Plasma free thyroxine concentrations were measured weekly for the first eight weeks after birth. Scores on the Bayley Mental and Psychomotor Development Indexes and neurologic function were assessed at 6, 12, and 24 months of age (corrected for prematurity).
Results:
Mortality and morbidity up to the time of discharge from the hospital were similar in the study groups. At 24 months of age, 157 infants were evaluated. Overall, neither mental nor psychomotor scores differed significantly between the study groups at any time, nor was the frequency of abnormal neurologic outcome significantly different. In thyroxine-treated infants born at gestational ages of less than 27 weeks, the score on the Bayley Mental Development Index at 24 months of age was 18 points higher than the score for the infants with similar gestational ages at birth in the placebo group (P=0.01); for thyroxine-treated infants born at 27 weeks or later, the mental-development score was 10 points lower than that of their counterparts in the placebo group (P=0.03). There was no relation between the initial plasma free thyroxine concentration and the effect of treatment.
Conclusions:
In infants born before 30 weeks' gestation, thyroxine supplementation does not improve the developmental outcome at 24 months.