ESPE Abstracts

Purpose: Congenital hypothyroidism (CH) is a state in which thyroid hormones are insufficient at birth. This condition may last for a lifetime or may be transient. Due to the universal newborn screening test, almost all newborns are being screened for thyroid function in Korea. The study was aimed to see the predictors of transient congenital hypothyroidism with long-term follow-up of more than 3 years of CH in a single tertiary center.

Subjects and Methods: Children who has been diagnosed as CH with more than 3 year of follow-up were included in the study. Retrospective review of clinical, laboratory, and imaging data were performed based on medical records and analyzed using R 4.2.

Results: A total of 98 patients were included in the study. They had taken thyroid hormone under the diagnosis of congenital hypothyroidism and been followed more than 3 years in a single tertiary center. Mean T3, freeT4, and TSH levels prior to hormone treatment were 138.8, 1.01, and 84.5, respectively. Mean age at recent follow-up was 8.05 years. They were classified as transient CH (n=62, 63.3%) and permanent CH (n=36, 36.7%) during follow-up. T3 levels prior to medication (preT3) was lower in permanent CH compared to transient CH (113.2 vs. 154.3, P=0.05), and maximum dose of thyroid hormone (DT4max) was higher in permanent CH (71.1 ug vs. 36.6 ug, P< 0.001). Mean TSH levels prior to medication were not significantly different between two groups. 128.5 ng/dL of preT3 (sensitivity 63% specificity 66%) and 47.5 ug of DT4max (sensitivity 81%, specificity 79%) can be used as the cutoff values to predict permanent CH in the study.

Conclusions: The study showed that 63% of CH can discontinue the thyroid hormone replacement during follow-up. Maximum dose of thyroid hormone (DT4max) during follow-up and T3 levels prior to medication can be used as the cutoff values to predict permanent CH.