An Optimal Capillary Screen Cut-off of Thyroid Stimulating Hormone for Diagnosing Congenital Hypothyroidism: Data from a Pilot Newborn Screening Program in Delhi

ABSTRACT

Objective: To determine an appropriate cut-off of capillaryThyroid stimulating hormone (TSH) for congenitalhypothyroidism.Study design: Cross-sectional.Participants: 174,000 neonates born in different hospitals ofDelhi, India, from November 2014 to October 2016.Main outcome measures: Correlation between initial andrepeat capillary TSH level and subsequent venous free thyroxine(fT4) level.Results: 102 newborns with initial/ repeat capillary TSH level of≥20 mIU/L (n=174) were confirmed to have congenitalhypothyroidism at mean (SD) age of 5 (4) days. A goodcorrelation between capillary TSH level and confirmatory venousfT4 level and postnatal age of sampling was obtained (r -0.6,-0.4). The area under the ROC curve (AUC) was 0.81 (95%CI0.75 to 0.88), indicating referral capillary TSH level of 20 mIU/L tobe a good predictor of subsequent high venous TSH level.Conclusion: A cut off of ≥20 mIU/L for capillary TSH screeningbeyond 24 hours of life is optimal in the Indian setting for decidingfurther recall and workup, keeping a balance between sensitivityand recall rate.