BACKGROUND:
Previous studies have reported an increased incidence of thyroid dysfunction in premature/low birth weight infants. The cord blood concentrations of transthyretin (TTR), a thyroid hormone binding protein, have also been found to be decreased in preterm infants. While thyroid hormone concentrations are decreased in sick infants, it is not known if physical condition influences TTR levels. Serial concentrations of TTR following birth have not previously been reported.
AIMS:
To measure serial serum concentrations of TTR in premature infants following birth, and determine whether TTR levels are related to physical condition.
METHODS:
A cohort of 65 premature very low birth weight (VLBW) and LBW infants were studied. Serum samples were obtained on the day of birth, and for 8 weeks following birth. Apgar scores at birth as well as the incidence of respiratory distress syndrome (RDS) were noted.
RESULTS:
Baseline serum T4 concentrations and Apgar scores were significantly lower in VLBW infants, while the severity of RDS was significantly higher in the VLBW group. Multivariate analyses revealed that T4 levels were negatively associated with RDS, while TSH concentrations were positively related to gestational age. TTR concentrations were not related to gestational age at birth, Apgar score, or RDS, and did not change markedly over 8 weeks.
CONCLUSIONS:
These findings suggest that serum TTR concentrations are not related to birth weight/gestational age and are not associated with either clinical condition at birth (as assessed by Apgar score) or the occurrence of RDS. Reference values for TTR concentrations in VLBW and LBW infants are provided from birth to 8 weeks of age.
