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

Objective To determine an appropriate cut-off of capillary Thyroid stimulating hormone (TSH) for congenital hypothyroidism. Study design Cross-sectional. Participants 174,000 neonates born in different hospitals of Delhi, India, from November 2014 to October 2016. Main outcome measures Correlation between initial and repeat 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 congenital hypothyroidism at mean (SD) age of 5 (4) days. A good correlation between capillary TSH level and confirmatory venous fT4 level and postnatal age of sampling was obtained (r -0.6, -0.4). The area under the ROC curve (AUC) was 0.81 (95%CI 0.75 to 0.88), indicating referral capillary TSH level of 20 mIU/L to be a good predictor of subsequent high venous TSH level. Conclusion A cut off of ≥20 mIU/L for capillary TSH screening beyond 24 hours of life is optimal in the Indian setting for deciding further recall and workup, keeping a balance between sensitivity and recall rate.