Studying Effect of Pregnancy on Levels of TT4 and FT4 Indicators in Serum Pregnant Women in Diyala Province

Background: Thyroxine is crucial for fetal development, especially brain growth. During pregnancy, physiological changes affect thyroid function, causing increased TT4 levels and variable FT4 levels, influenced by TBG, hCG and iodine availability. Detecting effect of pregnancy on levels of TT4 and FT4 in pregnant women in Diyala province. Methods: The research was conducted at Al-Batool Teaching Hospital in Diyala province from November 2024 to January 2025, involving 60 blood samples from pregnant patients and 30 healthy individuals as a control. Serum levels of FT4 and TT4 indicators were quantified using a Biorex machine. Results: The study found that pregnant women have higher levels of TT4 indicator compared to non-pregnant women, with a significant difference (p<0.05). However, no significant difference was found between FT4 and study groups. The ROC curve showed TT4 having the highest sensitivity and specificity (94 and 90%) for diagnosing thyroid disorders in pregnant women, while FT4 had the lowest sensitivity and specificity (55 and 54%). A significant positive correlation was found between FT4 and TT4 indicators in pregnant women. Conclusion: Pregnancy significantly impacts thyroid gland function, leading to significant changes in TT4 levels but not FT4 due to physiological and hormonal disorders. The TT4 is preferred for thyroid disorder screening.