Thyroid function in preterm infants 27-29 weeks of gestational age during the first four months of life: results from a prospective study comprising 80 preterm infants

• Published in: Journal of pediatric endocrinology & metabolism : JPEM Vol. 20; no. 12; p. 1269
• Main Authors: Clemente, María, Ruiz-Cuevas, Pilar, Carrascosa, Antonio, Potau, Neus, Almar, Jordi, Salcedo, Salvador, Yeste, Diego
• Format: Journal Article
• Language: English
• Published: Germany 01-12-2007
• Subjects: Birth Weight - physiology; Databases, Factual - statistics & numerical data; Gestational Age; Humans; Infant, Newborn - blood; Infant, Newborn, Diseases - blood; Infant, Newborn, Diseases - diagnosis; Infant, Newborn, Diseases - epidemiology; Infant, Premature - blood; Infant, Premature - physiology; Longitudinal Studies; Neonatal Screening - methods; Prospective Studies; Spain - epidemiology; Thyroid Function Tests; Thyroid Gland - physiology; Thyrotropin - blood; Thyroxine - blood; Time Factors; Triiodothyronine - blood; Triiodothyronine, Reverse - blood; Spain
• ISSN: 0334-018X
• DOI: 10.1515/JPEM.2007.20.12.1269

Assessment of thyroid function in preterm neonates (PTN) 27-29 weeks of gestational age.
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.
In healthy and sick preterms, TSH values peaked at 1 hour and decreased thereafter. 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).
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.