Recall Rate in Congenital Hypothyroidism Screening: Influence of the Day of Sample Collection and Lower Cutoff.

INTRODUCTION: The recall rate in congenital hypothyroidism (CH) newborn screening programs depends on several factors such as primary screening strategy, sample collection guidelines, and cut-off. A recall rate of 0.05% is recommended but recall rates of 0.01-13% are reported worldwide.
OBJECTIVE: The aim of the study was to assess the recall rate in association with the age of the newborn at sample collection and with a lower cut-off.
DESIGN: This was a retrospective correlational study concerning TSH results in CH screening program. SUBJECTS AND METHODS: All newborns from a tertiary center in Targu Mures, Romania between 2013-2018 were included. Four groups were created and a correlation test between TSH median value and age in days was performed. The recall rate was calculated using three cut-off levels for 8182 TSH results performed in 2018.
RESULTS: 90% of the DBS were collected in days 3-5 after birth and 1/79 live births from this group had TSH above the lower cut-off used (10 mUI/L). 2% of the samples were collected in less than 48 hours after birth and 1/21 live birth from this group had TSH > 10 mUI/L. The recall rate in our center in 2018 was 0.08%, higher than the recommended rate of 0.05%. With the cut-off value recommended by the Health Ministry a 0.03% recall rate was obtained.
CONCLUSIONS: Sample collection in less than 48 hours increases the recall rate in CH screening with TSH primary testing strategy. A lower cut-off raises the recall rate with a higher rate of false-positive cases (94.12%) but with 100% negative predictive value. ©by Acta Endocrinologica Foundation.