Catalase Activity and Methylglyoxal Concentration in Plasma and Erythrocytes Across Different Clinical Phenotypes of Thyroid Disease: A Cross-Sectional Study

Background/Objectives: Thyroid disorders may involve systemic oxidative and carbonyl disturbances, but compartment-specific changes in catalase activity and methylglyoxal concentration across different clinical phenotypes remain unclear. This study aimed to evaluate catalase activity and methylglyoxal concentrations in erythrocytes and plasma across predefined clinical phenotypes representing different combinations of thyroid functional, autoimmune, and structural characteristics and to examine correlations among these variables within and between the erythrocyte and plasma compartments.