Evaluating the Value of Quadruple Thyroid Screening in the Diagnosis of Hypothyroidism among Premature Neonates in Tehran in ۲۰۱۹-۲۰۲۰

Background: Neonate screening is a preventative measure that can contribute to early diagnosis of treatable diseases. Hypothyroidism in neonates is among the common preventable factors leading to intellectual disability. This study aims to describe the prevalence and experience with four-step screening to diagnose congenital hypothyroidism.Methods: The statistical population of this cross-sectional study included ۳۹۲ preterm neonates (gestational ages less than ۳۶ weeks and ۶ days) in ۲۰۱۸-۲۰۱۹ from the health centers covered by Shahid Beheshti University of Medical Sciences (Tehran, Iran) who had been referred for screening. Neonates were screened in the first ۳-۶ days after birth and then on days ۱۴, ۴۲, and ۷۲. In neonates with TSH serum levels of ۱۰ mU/L, TSH-T۴ was measured. Next, the physician decided on the medication based on the results.Results: At the primary screening of the neonates average TSH level was ۲.۰۸ ± ۲.۴ mU/L. Thirty-three neonates (۸.۴%) indicated disrupted screening results. The secondary screening of ۳۸۸ neonates (۹۸.۹۷%) revealed an average TSH serum level of ۱.۹ ± ۱.۹۶ mU/L, and ۱۹ (۵.۹%) indicated TSH serum levels higher than ۵ (mU/L). The third screening test was performed on ۳۸۲ (۹۷.۴۴%) of the neonates. The average TSH level was ۱.۳ ± ۲.۴ mU/L, ۳۴۰ (۸۵.۹۶%) indicated normal levels, and ۴۲ (۱۱.۴۷%) had unfavorable results. Finally, the fourth screening test was performed on ۳۷۳ (۹۵.۱۵%) neonates. The mean TSH level was ۲.۲۱ ± ۱.۹ mU/L, which revealed ۲۴ (۶.۱۲%) unfavorable test results. The percentage of hypothyroidism in neonates was ۵.۶% (۲۳ cases).  In this study, the prevalence of hypothyroidism was ۴.۳۳% (۱۷ cases) in girls and ۱.۵۳% (۶ cases) in boys.   Conclusion: The results of this study revealed the high incidence rate of congenital hypothyroidism among preterm neonates. Therefore, preventing congenital hypothyroidism misdiagnosis requires a series of screening tests. Also, findings indicated that the results of screening tests for preterm neonates with prolonged GAs and higher birth weights are more accurate and reliable.