Aim: Assessment of thyroid function in preterm neonates (PTN) 27-29 weeks of gestational age. Patients and Methods: 80 PTN, gestational age 27 weeks in 24, 28 weeks in 28, and 29 weeks in 28. Neonates were classified as healthy (n = 17) or sick (n = 63). Measurement of serum TSH, free T4, T4, T3 and rT3 in the mother and in the cord at the time of delivery, and in the infant at 1 hour, 24 hours, 1 week, 3 weeks, and 2 and 4 months of postnatal age. Results: In healthy and sick preterms, TSH values peaked at 1 hour and decreased there-after. Healthy PTN presented a peak in free T4 values at 24 hours that was not observed in sick neonates. Sick PTN had a lower TSH peak and lower free T4 values at 24 hours and 1 week than healthy ones (p <0,05). Healthy PTN 27-29 weeks had lower TSH peak at 1 hour and lower free T4, T3 and T4 values during the first 2 months than healthy PTN 30-35 weeks (PTN30-35w) previously evaluated (p <0.05). However, at all postnatal times healthy preterms had free T4 values above -2 SD of the mean values of healthy PTN30-35w. A wide range of free T4 values was observed in the sick group. Free T4 values above -2 SD of the mean values of healthy PTN30-35w were detected in a high proportion of sick PTN (58.3% at 24 hours, 73.5% at 1 week, 93.9% at 3 weeks, 85.1% at 2 months and 100% at 4 months). Conclusions: Prematurity and disease influence thyroid function, and consequently thyroid function should be individually assessed in preterms 27-29 weeks of gestation during the first 2 months of life. © Freund Publishing House Ltd., London.
- Preterm neonate
- Transient hypothyroxinemia