Cord Blood TSH Level Variations in Newborn - Experience from A Rural Centre in Southern India

Universal screening of all neonates has for long been recognized as the most effective method to detect congenital hypothyroidism. However, various maternal as well as perinatal factors can influence the cord blood TSH levels.

To evaluate the effect of perinatal factors on cord blood TSH level variations in neonates born in a rural tertiary care institution in South India.

A cross-sectional study was done in 430 term neonates at birth to analyse the cord blood TSH levels and a repeat TSH estimation was done on 3rd postnatal day for those having abnormal values. The values were statistically analysed with respect to maternal, paternal and perinatal parameters.

The mean value of CBTSH was 12.88 mIU/mL. One hundred twenty five of the 430 neonates (29.06%) were found to have elevated CBTSH levels. Two babies (0.46%) had CBTSH levels below 2.3 mIU/mL. Repeat TSH estimation done on third postnatal day in the 127 babies who had abnormal CBTSH levels revealed only 5 (3.94%) babies had abnormal levels. Serum T4 levels done on the same sample showed abnormal values in 3 (2.67%) babies. CBTSH levels showed no gender varations but increased significantly with the gestational age of the baby (p=0.001). CBTSH levels increased with increasing maternal age (p<0.001) and were significantly higher in babies of mothers with history of hypothyroidism.

The incidence of congenital hypothyroidism was 3 in 430 babies, which was high compared to national and international references, highlighting the urgent need of universal screening giving importance to maternal factors also.