Thyroid Disorders and the Prevalence of Antithyroid Antibodies in Shiraz Population

Background and Objectives: Thyroid dysfunction is a common health problem affecting millions of patients worldwide. Autoimmune thyroid disorders are among the most common autoimmune disorders. In this population-based study, we assessed the prevalence of abnormal thyroid function, antithyroid antibodies and the probable relationship between them in Shiraz, southern Iran. Methods: Serum thyrotropin (TSH) was determined in 981 subjects (66.8% female and 33.2% male; mean age: 39.1 ± 14.3 years), who were selected with stratified random sampling. Because of the preponderance of females over males, we performed the statistical analyses using sex-weighted data (50% for each sex). Also, antithyroid peroxidase antibodies (TPOAb), and antithyroglobulin antibodies (TgAb) were measured in two random subgroups of 376 and 537 patients respectively). Thyromegaly detected on physical examination. Results: In this cross-sectional study, 8.1% of participants had elevated serum TSH level and 3.4% had low serum TSH level. A statistical- ly significant relationship was found between gender and thyromegaly and TSH values. Positive TPOAb and positive TgAb were detected in 17% and 5.1% of participants respectively. In addition, a significant relationship was observed between elevated TSH levels and positive results for both antibodies. Detectable levels of thyroid antibodies correlated with female sex, while no correlation was observed between detectable levels of thyroid antibodies and thyromegaly. Conclusion: Thyroid disorders, especially elevated TSH level, are common. It seems that autoimmune mechanisms are strongly involved in the etiology of hypothyroidism in this area.