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Motor nerve conduction velocity in very preterm infants in relation to L-thyroxine supplementation
B J Smit1, J H Kok, L S de Vries
1Academic Medical Center, University of Amsterdam, Emma Children's Hospital AMC Department of Neonatology, The Netherlands.
Insights
L-thyroxine supplementation in preterm infants did not significantly improve motor nerve conduction velocity. This study suggests early L-thyroxine treatment is not clearly beneficial for neurodevelopment in premature babies.
Area of Science:
- Neonatal Medicine
- Pediatric Neurology
- Endocrinology
Background:
- Transient hypothyroxinemia is common in preterm infants, linked to neurodevelopmental issues.
- The necessity of L-thyroxine supplementation in these infants remains unclear.
- Motor nerve conduction velocity (MNCV) is a marker for neurodevelopment.
Purpose of the Study:
- To investigate if L-thyroxine supplementation improves motor nerve conduction velocity in preterm infants.
- To assess the impact of early L-thyroxine administration on neurodevelopmental markers.
Main Methods:
- A randomized, double-blind, placebo-controlled trial involving 200 infants < 30 weeks gestational age.
- Infants received L-thyroxine (8 micrograms/kg/day) or placebo for the first 6 weeks of life.
- Motor nerve conduction velocity was measured at multiple time points: shortly after birth, 2, 40, and 66 weeks postmenstrual age.
Main Results:
- A non-statistically significant improvement in ulnar MNCV was observed at 2 weeks in the L-thyroxine group (p=0.06).
- No significant differences in MNCV were found between the L-thyroxine and placebo groups at later time points.
- The study did not find a clear benefit of L-thyroxine supplementation on MNCV.
Conclusions:
- Early L-thyroxine supplementation (first 6 weeks) does not significantly improve motor nerve conduction velocity in infants born before 30 weeks' gestation.
- The findings suggest L-thyroxine supplementation may not be routinely required for improving neurodevelopmental outcomes related to nerve conduction in this population.
- Further research may be needed to explore potential benefits in specific subgroups or at different dosages.
Background:
Transient hypothyroxinemia is common in preterm infants and has been associated with neurodevelopmental dysfunction and slow nerve conduction velocity. It is still unknown whether L-thyroxine supplementation is required. During an L-thyroxine supplementation trial, motor nerve conduction velocity was measured to answer the question whether L-thyroxine supplementation improves motor nerve conduction velocity.
Methods:
Two hundred infants < 30 weeks' gestational age were enrolled in a randomized, double-blind, placebo-controlled L-thyroxine supplementation trial. L-Thyroxine (8 micrograms/kg birthweight per day) or a placebo was administered during the first 6 weeks of life. Motor nerve conduction velocity was measured in the ulnar and posterior tibial nerve shortly after birth, at 2 weeks, at 40 weeks, and at 66 weeks postmenstrual age.
Results:
At 2 weeks, the ulnar motor nerve conduction velocity had improved in the L-thyroxine group compared with the placebo group, although the difference was not statistically significant (difference between means: 0.8 msec; 95% CI: -0.13 to 1.80; p = 0.06). Later on, no effect of L-thyroxine supplementation on motor nerve conduction velocity was found.
Conclusion:
This study shows that in infants < 30 weeks' gestational age L-thyroxine supplementation during the first 6 weeks of life does not clearly improve motor nerve conduction velocity.