Establishment of reference ranges for thyrotropin and free thyroxine forneonates of Bangalore city

Introduction and Aim:Congenital hypothyroidism (CHT) is a condition of thyroid hormone deficiency present at birth. To diagnose this condition, estimation of TSH and FT4 are essential. There is an urgent need to develop reference ranges for thyroid hormones for neonates because hypothyroidism is the most frequent thyroid disease encountered in pediatric age group and it requires early diagnosis to prevent the consequences, whichcan be lifelong. No reports exist in Indian literature regarding the establishment of reference ranges in India for thyroid profile for neonates and thus this study was carried out. Subjects and Methods:100 neonates were included in this longitudinal study. Serum TSH and freeT4 levels were estimated by using Electro-chemiluminescence, based on the Sandwich principle (Cobas, USA). The statistical analysis was performed using MedCalc software. Results:Mean and standard deviation of TSH in males and females were 4.33±4.25(?IU/mL) and 4.33± 3.99(?IU/mL) respectively. Mean and standard deviation of free T4 in males and females were 22.44 ± 5.31 (pmol/L) and 22.49±7.47 (pmol/L) respectively. The reference ranges of TSH in males are 0.18-15.76 ?IU/mL and in females is 0.17-15.68 ?IU/mL. The reference ranges of free T4 in males 14.19 –32.69 p mol/L and females 9.65-36.25 pmol/L. Conclusion:The reference range of TSH obtained in this study correlates with that of the western population and hence, it may be used as a stable parameter in the screening of neonates for congenital hypothyroidism. Keywords:Congenital hypothyroidism; thyroid hormones; reference range; neonates.