Introduction: Knee osteoarthritis (OA) is a chronic degenerative disorder influenced by metabolic, endocrine and inflammatory factors. Thyroid hormones regulate cartilage matrix turnover, while thyroid-stimulating hormone (TSH) influences bone remodeling. Alterations in thyroid profile may contribute to OA progression. Aim: To estimate serum T3, T4 and TSH levels in knee OA patients and compare them with age- and gender-matched controls. Materials & Methods: A case–control study was conducted on 103 knee OA cases and 103 healthy controls aged 40–70 years. Serum T3 and T4 were measured using competitive ELISA and TSH using sandwich ELISA. Statistical analysis was performed using SPSS v25. Results: OA patients showed significantly higher TSH levels compared to controls (p<0.001). T3 and T4 showed mild but notable alterations, especially in advanced Kellgren–Lawrence grades. TSH showed significant positive correlation with age , BMI and OA severity (KL grade). Conclusion: OA patients demonstrated altered thyroid hormone levels, particularly increased TSH. Thyroid dysfunction may play an important role in OA pathophysiology and can serve as a supportive biochemical marker.