Abstract
BACKGROUND: Babies born before 28 weeks' gestation have lower plasma thyroid
hormone concentrations than more mature infants. This may contribute to their
risk of poor developmental outcome. Previous studies have suggested that
thyroxine supplementation for extremely preterm neonates may be beneficial. The
aim of this study was to investigate the effect of administration of supplemental
thyroxine to very premature babies on brain size and somatic growth at 36 weeks'
corrected gestational age (CGA).
METHODS: In this explanatory multicentre double blind randomised placebo
controlled trial, 153 infants born below 28 weeks' gestation were randomised to
levothyroxine (LT4) supplementation or placebo until 32 weeks' CGA. The primary
outcome was brain size assessed by the width of the subarachnoid space measured
by cranial ultrasound at 36 weeks' CGA. Lower leg length was measured by
knemometry.
RESULTS: Babies in the LT4-supplemented and placebo groups had similar baseline
characteristics. There were no significant differences between infants given LT4
(n=78) or placebo (n=75) for width of the subarachnoid space, head circumference
at 36 weeks' CGA, body weight at 36 weeks' CGA or mortality. Infants who received
LT4 had significantly shorter leg lengths at 36 weeks' CGA although adjusted
analysis for baseline length did not find a statistical difference. There was a
significant correlation between low FT4 and wider subarachnoid space. No
unexpected serious adverse events were noted and incidence of adverse events did
not differ between the two groups.
CONCLUSION: This is the only randomised controlled trial of thyroxine
supplementation targeting extremely premature infants. Supplementing all babies
below 28 weeks' gestation with LT4 had no apparent effect on brain size. These
results do not support routine supplementation with LT4 for all babies born below
28 weeks' gestation.
TRIAL REGISTRATION: Current Controlled Trials ISRCTN89493983EUDRACT number:
2005-003-09939.
hormone concentrations than more mature infants. This may contribute to their
risk of poor developmental outcome. Previous studies have suggested that
thyroxine supplementation for extremely preterm neonates may be beneficial. The
aim of this study was to investigate the effect of administration of supplemental
thyroxine to very premature babies on brain size and somatic growth at 36 weeks'
corrected gestational age (CGA).
METHODS: In this explanatory multicentre double blind randomised placebo
controlled trial, 153 infants born below 28 weeks' gestation were randomised to
levothyroxine (LT4) supplementation or placebo until 32 weeks' CGA. The primary
outcome was brain size assessed by the width of the subarachnoid space measured
by cranial ultrasound at 36 weeks' CGA. Lower leg length was measured by
knemometry.
RESULTS: Babies in the LT4-supplemented and placebo groups had similar baseline
characteristics. There were no significant differences between infants given LT4
(n=78) or placebo (n=75) for width of the subarachnoid space, head circumference
at 36 weeks' CGA, body weight at 36 weeks' CGA or mortality. Infants who received
LT4 had significantly shorter leg lengths at 36 weeks' CGA although adjusted
analysis for baseline length did not find a statistical difference. There was a
significant correlation between low FT4 and wider subarachnoid space. No
unexpected serious adverse events were noted and incidence of adverse events did
not differ between the two groups.
CONCLUSION: This is the only randomised controlled trial of thyroxine
supplementation targeting extremely premature infants. Supplementing all babies
below 28 weeks' gestation with LT4 had no apparent effect on brain size. These
results do not support routine supplementation with LT4 for all babies born below
28 weeks' gestation.
TRIAL REGISTRATION: Current Controlled Trials ISRCTN89493983EUDRACT number:
2005-003-09939.
| Original language | English |
|---|---|
| Journal | Trials |
| Volume | 14 |
| Issue number | 211 |
| Publication status | Published - 2013 |