Umbilical cord blood TSH levels in term neonates: A screening tool for congenital hypothyroidism

Abstract

This study was conducted to find normative values for thyroid stimulating hormone (TSH) in 1200 cord blood samples of term babies whose mothers were not on any thyroid medications. TSH was estimated within 24hrs by enzyme immunoassay. A full thyroid profile, viz, T3, T4, TSH, fT3 and JT4 was done at 7-10 days of age in all babies with cord TSH >20mIU/L. The mean, median and standard deviation for the TSH values for the cohort were 6.13 mIU/L, 5.8 mIU/L and 4.523 respectively. 22 babies with TSH values >20mIU/L were given repeat tests. Hypothyroidism was confirmed in two of these babies. We conclude that a cut off value of TSH >20mIU/L is adequate for neonatal thyroid screening in Indian settings.