European Journal of Molecular & Clinical Medicine

Introduction: Congenital Hypothyroidism is one of the most common causes of preventable mental
retardation with an estimated incidence of 1:2500-2800 live births in India. The need for neonatal
screening for CH is essential as the majority of signs and symptoms are not exhibited in the neonatal
period.
Aim: To use TSH values as a marker for screening for Congenital Hypothyroidism in neonates in an
iodine deficient endemic region and to find normative values of Serum TSH for the study group.
Material and Methods: A prospective observational study was conducted over a period of 18 months.
A total of 500 newborns who fulfilled inclusion criteria were enrolled. Umbilical Cord Blood samples
(2ml from placental side) were taken for TSH values for all Term neonates with birth weight ≥ 2.5 Kgs
whereas Serum TSH values at 48-72 hours of life were taken for Preterm (<37 completed weeks) and
Low birth weight neonates. All babies who had a cord blood TSH value of >20 mIU/L were sampled
again for TSH and T4 and if repeat TSH was >20 mIU/L and/or T4 < 10 mIU/L they were subjected for
further examination and treatment if required.
Results: The mean cord blood TSH was 7.26 mIU/L in our study, with 7.28 mIU/L in term neonates and
6.94 mIU/L in preterm neonates. Nine babies had TSH values >20mIU/L in the initial screen but all were
<20 mIU/L on repeat sampling. Hence none of the 500 neonates who were screened for CH in our study
were detected to have congenital hypothyroidism. TSH values corresponding to the 5th, 10th, 25th, 50th,
75th and 95th percentile were 3.08, 4.71, 5.39, 13.18, 21.65 and 39.22 respectively. The babies born to
mothers with hypothyroidism, had higher TSH values compared to those without risk factors.
Conclusion: In our study, none of the 500 newborns screened had congenital hypothyroidism. We
observed that neonates born to mother with hypothyroidism had higher cord blood TSH which was
statistically significant. According to our normogram, the 50th centile corresponded to 13.18 mIU/mL
which is <20 mIU/mL while neonates above 75th centile had TSH values above 20 mIU/ml.