Cord Blood TSH and Free T4 Correlation with Maternal and Neonatal Factors and Heel-Stick TSH For the Early Detection of Congenital Hypothyroidism: A Cross-sectional Study in Iran

Abstract

Background- Congenital hypothyroidism (CH) is the most frequent cause of mental retardation in children. Despite the success of the screening programs in detecting CH cases, high recalling rate and false positive results impose a burden to the health system worldwide. Although cord blood thyroid stimulating hormone (CBTSH) is an accepted screening tool for CH, data about it are sparse in Iran. Therefore, we aimed to evaluate the umbilical cord blood TSH and Free T4 and its relationship with maternal and neonatal factors, as well as heel-stick TSH. Methods- This study included 120 mother-newborn pairs in Amir-Al-Momenin Hospital, Semnan, Iran from October 2021 to May 2022. The mean values of Free T4 and CBTSH were measured with respect to various maternal and neonatal factors. The heel-stick TSH on day 2-3 after birth were determined in all participants. Results- The mean CBTSH concentration was significantly higher in preterm newborns and male sex than term newborns and females (P=0.039 and P<0.001, respectively). Newborns born via cesarean section had lower CBTSH levels than those born by vaginal deliveries (P=0.040). The CBTSH was also positively correlated with heel-stick TSH (P<0.001). The mean umbilical cord blood Free T4 was significantly higher in multigravida newborns than primigravida cases (P=0.023). There was no statistically significant relation between umbilical cord blood Free T4 and TSH and maternal age, preeclampsia, gestational diabetes, twin or singleton delivery, 1- and 5- minutes Apgar scores, birthweight, and cord gases (P>0.05). The optimal cut-off point of CBTSH for discrimination of suspicious cases to hypothyroidism was 14.75 mIU/L. Conclusions- Method of delivery, gestational age, and male sex were influential variables on the umbilical cord TSH that must be considered when interpreting the results of the CBTSH. This study augments findings that CBTSH may be considered a predictive factor in CH screening programs.