Thyroid Function Test in Preterm Neonates: Normative Data.

Introduction: Initial surge of thyroid-stimulating hormone (TSH) in neonates increases free and total triiodothyronine (T3) and tetraiodothyronine (T4) in 24-36 hours following birth, and the effect then gradually wanes off. As somatic and intellectual development is dependent on normal thyroid function especially in infancy, normative data in these children may be of immense value to diagnose hypothyroidism in this subset of infants. Comprehensive normative values of thyroid function parameters in preterm neonates are scarcely available.