Cord Blood versus Peripheral Venous Blood Sample of Thyroid Stimulating Hormone for Neonatal Thyroid Screening
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Abstract
Background :Congenital hypothyroidism remains one of the most common preventable causes of mental retardation among children.There is limited data available on cut off criteria for defining congenital hypothyroidism in India and efficacy of cord blood TSH level to detect congenital hypothyroidism, hence this study is planned.
Aim :To study efficacy of cord blood TSH as a screening tool to detect congenital hypothyroidism and to define cut off level for cord blood TSH and peripheral venous blood TSH on 4thpost natal day for screening congenital hypothyroidism.
Methods :This was hospital based cross-sectional observational study, carried out from July 2020 and January 2021. After enrolling live newborns >34 weeks of gestation,TSH assay was performed on cord blood and peripherally obtained venous blood on 4th postnatal day of life, results of which were compared using chi square test. P value < 0.05 was considered to be statistically significant.All babies with VBTSH >10microU/ml were followed up with repeat serum TSH value after 2 weeks.
Results :Total 122 babies were enrolled in the study out of whom, only 7.38% babies had elevated CBTSHand only 0.8% had elevated VBTSH. There was positive correlation between CBTSH and VBTSH. Parameters like maturity of baby and birth weight were found to be statistically non significant with CBTSH & VBTSH.
Conclusion :Venous blood TSH value of > 10 mIU/mL on fourth postnatal day signifies congenital hypothyroidism. Cord blood TSH value of >20 mIU/mL can be safely used as a cutoff for the purpose of screening for congenital hypothyroidism in countries like India.