Thyroid Function in Preterm Infants with Respiratory Distress Syndrome and Bronchopulmonary Dysplasia

Kim, Sun Ye; Han, Man Yong; Lee, Kyu Hyung

Abstract

PURPOSE: It has been known that intrauterine thyroid hormone deficiency may be one of the factors predisposing to RDS in premature infants. The aims of the study was to predict the development of respiratory distress syndrome (RDS) and bronchopulmonary dysplasia (BPD) with the serial serum thyroid hormone concentrations in premature infants.
METHODS
From April 1998 to July 1999, we measured serum T3, T4, FT4. and TSH levels at less than 24 hours, 7, and 28 days of age in 57 premature infants. Study infants were divided into 3 groups according to their respiratory disease : the healthy premature group (A), the RDS without BPD group (B), and the BPD group (C). We compared the thyroid function among these three groups.
RESULTS
Out of total 57 premature infants, 11, 33, and 13 infants belong to the Group A, B, and C, respectively. In all three groups, T3 and T4 levels were slightly decreased at 7 days and then increased at 28 days of age, whereas TSH level was highest in the first day of life and progressively decreased with time. In the first day of life, T3, T4, FT4, and TSH levels were highest in group A, middle in group B, and lowest in group C. In group C, T3 and T4 levels at 24 hours and 7 days of age were significantly lower than those in group A (P<0.05). T4, FT4 levels at 24 hours of age and T3, T4 levels at 7 days of age in group C were significantly lower than those in group B (P<0.05). There were no significant differences in thyroid function between groups A and B at any ages, and among all three groups at 28 days of age.
CONCLUSION
There were no differences in thyroid function between the healthy premature infants and the infants with RDS who did not develop BPD later. However, in the infants with BPD, thyroid functions within 24 hours after birth and at 7 days of age were significantly lower than those in the premature infant without BPD. These observations support that early postnatal thyroid hormone concentrations are not related to the development of RDS, but useful as a predictive factor for the development of BPD in premature infants.