Association Between CMV Infection and Autoimmune Thyroid Dysfunction in Kirkuk, Iraq

Background: Thyroid dysfunction is a common endocrine disorder that may result from autoimmune, genetic, or infectious causes. Aim: This study aimed to explore the relationship between CMV infection and thyroid dysfunction in relation to anti-thyroid peroxidase (antibody positivity). Methods: A cross-sectional study was conducted in Kirkuk, Iraq, from October 2024 to April 2025. It included 100 patients with thyroid dysfunction (13 hyperthyroid, 87 hypothyroid) and 50 healthy controls. Serum samples were analyzed for TSH, T3, T4, anti-TPO antibodies, and CMV IgM/IgG. Results: CMV seropositivity was significantly associated with thyroid dysfunction (P = 0.038). Among hyperthyroid patients, 30.77% were CMV IgG positive and 7.69% had combined IgM and IgG positivity. In hypothyroid patients, 21.84% were CMV IgG positive and 10.34% showed co-positivity. Anti-TPO antibody positivity was found in 23% of patients. A strong and statistically significant association was observed between Anti-TPO positivity and CMV IgM/IgG co-positivity (34.78% vs. 2.60% in Anti-TPO negatives; P = 0.001). Gender-stratified analysis revealed that CMV IgM/IgG co-positivity was markedly more prevalent in Anti-TPO positive males. Conclusion: The findings indicate a significant relationship between CMV infection and thyroid dysfunction, especially hypothyroidism with autoimmune features. CMV may act as a triggering factor in thyroid autoimmunity.