The recall prevalence in congenital hypothyroidism screening due to thyroid stimulating hormone levels among newborns using dried blood spot samples in Thailand from 2015 to 2022

Abstract

The measurement of thyroid stimulating hormone (TSH) levels in dried blood spots (DBS) samples collected from newborns aged 48-72 hours using the ELISA technique has been a common practice for neonatal screening for congenital hypothyroidism (CHT) in Thailand since 1996. A TSH level of ≥ 25 mU/L is the established cutoff value for recalling newborns for further confirmation testing. In compliance with national guidelines, the newborns testing positive should receive prompt treatment within 14 days old. This study aims to assess the recall rate prevalence and determine the incidence of CHT through the screening program administered by the National Neonatal Screening Operation Center under the Department of Medical Sciences from 2015 to 2022. A total of 4,621,808 newborns were screened, covering 96.12% of total live births. Of these, 21,970 newborns (0.48%) required the confirmation tests for CHT positive, but only 13,021 (59.27%) responded to receive the confirmation test. Among these cases, 2,706 were found to be abnormal, resulting in an incidence rate of 1 in 1,708 with a positive predictive value (PPV) of 20.78%. Results indicated that, for each year, an increasing prevalence of recalled cases corresponding to a higher incidence rate of CHT. Therefore, conducting confirmation tests for all screened abnormal newborns could provide a more accurate depiction of the actual incidence of CHT in Thailand.