Low triiodothyronine concentration in preterm infants and subsequent intelligence quotient (IQ) at 8 year follow up

Abstract

We measured plasma triiodothyronine concentrations longitudinally in 279 infants in samples taken at 1-3 days and 4-7 days and then weekly until the infant was discharged from hospital or weighed 2000 g.³ IQ was assessed in 236 infants (94% of survivors) at 7.5-8 years by means of an abbreviated version of the revised anglicised Weschler intelligence scales for children, which has five subscales and a correlation with full scale IQ of 0.96. In those children whose minimum triiodothyronine concentration was below 0.3 nmol/l³ we found substantial deficits in IQ scores, even after adjustment for birth weight, gestation, sex, and Apgar score at 5 minutes (table 1). The effect was independent of the duration of artificial ventilation.