Thyroid function in prematures with respiratory distress syndrome (RDS)

Reports on thyroid function in newborns with respiratory distress syndrome (RDS) are controversial, the significance of obtained results is not clear. Therefore we conducted a longitudinal study of thyroid function in 35 infants with RDS (gestational age 24-36 weeks, birth weights 650-2770 g). 43 well prematures, matched for gestational age, served as controls. No significant differences were observed in cord blood TSH, T3, T4, TBG values and T4:TBG ratios between infants with and without RDS. Prematures with RDS showed lower levels of T3, T4, TBG and T4:TBG at 24 hours of age and increases of TSH values at 72 hours. Subsequently these prematures exhibited a spontaneous rise in thyroid hormone levels. Even non-surviving RDS-infants had initial T3, T4, T4:TBG and TSH values within the normal range. Thyroid hormone concentrations correlated significantly with the severity of pulmonary disease. Depressed thyroid hormone levels were found to be the result and not the cause of RDS. T4 or T3 therapy is not warranted in this condition.