Assessment of thyroid autoimmunity and serum ferritin profiles in hypothyroid versus euthyroid individuals

Background: Thyroid autoimmunity and iron metabolism are closely interlinked, with serum ferritin serving as a marker of iron stores and inflammation. Hypothyroidism is often associated with both autoimmunity and altered ferritin levels. Aims and Objectives: To evaluate thyroid autoimmunity status and serum ferritin levels in hypothyroid and euthyroid individuals and to assess their correlation. Materials and Methods: A prospective case–control study was conducted in 140 participants, including 70 hypothyroid patients and 70 age- and gender-matched euthyroid controls. Serum-free triiodothyronine (FT3), free thyroxine (FT4), thyroid-stimulating hormone (TSH), and ferritin were measured using chemiluminescent immunoassay, while anti-thyroid peroxidase (anti-TPO) antibodies were estimated by enzyme-linked immunosorbent assay. Statistical comparisons and correlations were performed, with P<0.05 considered statistically significant. Results: Hypothyroid patients showed significantly lower FT3 (1.4±0.36 pg/mL vs. 2.75±0.26 pg/mL, P<0.001), FT4 (0.7±0.36 pg/mL vs. 1.82±0.28 pg/mL, P<0.001), and ferritin (10.54±3.75 ng/dL vs. 57.92±39.38 ng/dL, P<0.001) compared to controls. TSH and anti-TPO antibodies were significantly elevated in hypothyroid individuals (7.76±1.9 mU/L and 221.4±98.71 IU/mL, respectively; P<0.001). A moderate positive correlation was observed between ferritin and anti-TPO in euthyroid participants (r=0.40, P=0.0044), but not in hypothyroid patients. Conclusion: Hypothyroidism is associated with significantly reduced serum ferritin and elevated anti-TPO antibodies, reflecting the interplay between iron deficiency and thyroid autoimmunity. Routine assessment of ferritin in hypothyroid patients may improve management, particularly in populations at risk of iron deficiency.