Thyroid function in premature infants.

Abstract

The present study was performed using the simultaneous assays of free T4 and TSH levels in dried blood spots of filter paper for mass-screening of inborn errors of metabolism in order to clarify the thyroid function of premature infants. The subjects were divided in three groups: A group infants less than 1500 g at birth (n = 34, 27.4 +/- 2.6 weeks of gestational age), B group infants from 1500 to 2500 g at birth (n = 104, 35.6 +/- 2.4 weeks) and C group infants over 2500 g at birth (n = 490, 39.0 +/- 1.2 weeks). TSH levels were 4.51 +/- 3.03, 2.62 +/- 2.24 and 2.84 +/- 2.06 microU/ml in A, B and C group respectively and significant difference was recognized in group A and C. Free T4 levels were 0.71 +/- 0.42, 1.81 +/- 0.96 and 2.15 +/- 0.67 ng/dl, in group A, B and C respectively, and significant differences were recognized in all three groups. There was positive correlation between free T4 levels and gestational ages (Y = -2.413 +/- 0.11725X, r = 0.206, p less than 0.05).