Systemic antioxidant status in women with chronic tendinopathy: a pilot case-control study

Oxidative stress is increasingly recognized as an important contributor to tendon degeneration; however, evidence on systemic antioxidant biomarkers in tendinopathy remains limited. This pilot case–control study investigated serum paraoxonase-1 (PON-1) levels and vitamins A and E in women with chronic tendinopathy. Thirty-four female patients with clinically and ultrasonographically confirmed tendinopathy and 31 age- and body mass index-matched healthy controls were included. Serum PON-1 levels were measured using enzyme-linked immunosorbent assay, and vitamins A and E were quantified by high-performance liquid chromatography. Compared with controls, patients demonstrated significantly lower PON-1 levels (5.31 ± 1.67 vs. 6.36 ± 1.88 ng/mL, p = 0.021), vitamin A levels (0.53 ± 0.16 vs. 0.75 ± 0.31 µmol/L, p = 0.001), and vitamin E levels (7.58 ± 1.86 vs. 16.91 ± 7.09 µg/mL, p < 0.001). A positive correlation was observed between vitamin A and vitamin E in both groups (patients: r = 0.422, p = 0.013; controls: r = 0.630, p < 0.001). These findings support the presence of systemic oxidative imbalance in chronic tendinopathy. Future longitudinal and interventional studies are warranted to clarify whether systemic redox status is associated with symptom burden, functional outcomes, and rehabilitation response.