Biochemical Evaluation of Thyroid Dysfunction in Patients with Autoimmune Disorders in Ibadan

Autoimmune thyroid disease, encompassing Hashimoto's thyroiditis and Graves' disease, frequently coexists with other systemic autoimmune conditions, creating diagnostic complexity in clinical settings. This study evaluates thyroid function tests and thyroid autoantibodies in patients with established autoimmune disorders including rheumatoid arthritis, systemic lupus erythematosus, and type 1 diabetes attending a specialist clinic in Ibadan, South West Nigeria. A cross-sectional design was adopted, recruiting 120 patients with confirmed autoimmune diagnoses. Serum TSH, free T4, free T3, anti-thyroid peroxidase antibodies, and anti-thyroglobulin antibodies were measured by ELISA. Clinical features of thyroid dysfunction were assessed by structured clinical interview. The prevalence of subclinical and overt thyroid dysfunction was determined and compared across autoimmune diagnoses. Logistic regression was used to identify clinical and biochemical predictors of thyroid autoantibody positivity. Findings will demonstrate the importance of routine thyroid function screening in patients with autoimmune diseases and will contribute to integrated autoimmune management guidelines in South West Nigeria. Keywords: autoimmune thyroid disease, TSH, thyroid autoantibodies, rheumatoid arthritis, Ibadan.