The relationship between thyroid functions and levels of selenoprotein P and glutathione peroxidase 3 in thalassemia major patients

Objective: There have been studies measuring selenium levels and glutathione peroxidase 3 activity (GPX3) in patients with thalassemia major (TM). However, selenoprotein P (SePP), which is responsible for the storage and transport of selenium, has not been studied in thalassemia patients. The aim of this study is to compare the thyroid functions of the thalassemia major patients with the levels of SePP and GPX3 and to evaluate the effect of selenoproteins on thyroid function. Methods: Eighty patients (40 controls, 40 TM) were included in this study. GPX3 and Selenoprotein P concentrations in the control and patient groups were measured by sandwich ELISA. The hemogram was measured with the Advia 120 device. Ferritin, T4, T3 and TSH samples were analyzed by using immunological method. Iron was measured spectrophotometrically using Advia Chemistry XPT. Anti-TPO and Anti-hTG were studied by immunoassay method using the immulite 2000 device. Iodine was measured spectrophotometrically in urine. Results: SePP concentration of thalassemia major group was higher than control group. There was no statistically significant difference between the GPX3 concentrations of the TM patients and the GPX3 concentrations in the control group. A negative correlation was found between ferritin concentrations of all individuals and concentrations of free T4 and T3. A negative correlation was found between the GPX3 concentrations of all subjects and free T4 and T3 concentrations. There was a negative correlation between SePP and TSH concentrations in healthy subjects. Conclusion: This is the first study in which the concentrations of SePP and GPX3 were measured together in thalassemia patients. In our study, SePP levels were higher in TM patients than in the control group but there was no difference in GPX3 levels of the groups. It was shown that there may be a relationship between iron overload and thyroid hormones. Correlations between thyroid hormones and selenoproteins may indicate that selenium is necessary for thyroid functions. Detailed studies are needed to clarify the role of SePP in thyroid metabolism in thalassemia Keywords: thalassemia, selenoprotein P, glutathione peroxidase, hypothyroidism