ETA2022 Poster Presentations Hypothyroidism Treatment (10 abstracts)
Whole-body oxidative stress measured by biomarkers of RNA and DNA damage is higher in hypothyroid women, even after treatment, than in healthy individuals, measured by biomarkers of RNA and DNA damage
Kamilla R. Riis 1 , Camilla B. Larsen 1 , Bjarke R. Medici 2,3 , Christian Z. Jensen 2 , Kristian H. Winter 1 , Emil L. Larsen 3 , Andreas Brønden 3 , Christina Ellervik 4,5,6 , Jeppe L. la Cour 2 , Laszlo Hegedüs 1 , Thomas H. Brix 1 , Henrik E. Poulsen 3,7 , Jens Faber 2 , Filip K. Knop 2,3 , Birte Nygaard 2 & Steen J. Bonnema 1
1Research unit at the Department of Endocrinology, Odense University Hospital, Denmark; 2Department of Medicine, Herlev Hospital and Gentofte, University of Copenhagen, Denmark; 3Center for Clinical Metabolic Research, Herlev and Gentofte Hospital, University of Copenhagen, Denmark; 4Department of Clinical Medicine, Boston Children’s Hospital, USA; 5Department of Clinical Medicine, University of Copenhagen, Denmark; 6Department of Production, Research, and Innovation, Region Zealand, Denmark; 7Laboratory of Clinical Pharmacology Q7642, Rigshospitalet, Copenhagen University Hospital, Denmark;
Introduction: Hypothyroidism has been associated with oxidative stress. Urinary excretion of 8-oxo-7,8-dihydroguanosine (8-oxoGuo) and 8-oxo-7,8-dihydro-2’-deoxyguanosine (8-oxodG), respectively, represent whole-body RNA and DNA oxidation. While these biomarkers have been associated with increased morbidity and mortality in various diseases, they have been only sparsely explored in patients with thyroid disorders.
Method: In 45 women with newly diagnosed hypothyroidism (overt: n = 23; subclinical: n= 22), urinary excretions of 8-oxoGuo and 8-oxodG, corrected for creatinine, were measured before or shortly after initiation of levothyroxine (LT4), and again after 6-12 months of euthyroidism. Eighteen healthy women were included as controls.
Results: The hypothyroid women and the controls had a mean age of 47.4±11.4(SD) and 45.2±13.1(SD) years, respectively. There was no difference in age, BMI, and smoking status between patients and controls. In the patients, none of the biomarkers changed significantly by achievement of euthyroidism. Thus, the geometric mean of 8-oxoGuo was 1.63 (95%CI: 1.49-1.78) nmol/mmol creatinine at baseline and 1.67 nmol/mmol (95%CI: 1.53-1.83) at euthyroidism (P = 0.39), while 8-oxodG was 1.28 nmol/mmol (95%CI: 1.14-1.44) and 1.32 nmol/mmol (95%CI: 1.18-1.48), respectively (P = 0.47). In the control group, the geometric mean of 8-oxoGuo was 1.23 nmol/mmol creatinine (95%CI: 1.07;1.42), while 8-oxodG was 1.04 nmol/mmol creatinine (95%CI: 0.88;1.23). Thus, the patients at euthyroidism, compared with control subjects, showed a significantly higher level of both 8-oxoGuo (P < 0.001) and 8-oxodG (P = 0.03). Among patients, a multiple regression analysis demonstrated a negative correlation between TSH and 8-oxoGuo, and a positive correlation between free T4 and 8-oxoGuo, at baseline. A positive correlation between baseline free T4 and 8-oxodG was also demonstrated.
Conclusion: In hypothyroid women, no significant effect of LT4 treatment was demonstrated on the oxidative stress biomarkers 8-oxoGuo and 8-oxodG. The excretion of these biomarkers was significantly higher in patients than in healthy individuals. It is speculated whether the increased oxidative stress burden reflects the impact of thyroid autoimmunity per se.
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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