Prevalence of Functional Alterations and the Effects of Thyroid Autoimmunity on the Levels of TSH in an Urban Population of Colombia: A Population-Based Study

Background: The population prevalence of functional alterations and thyroid autoimmunity is high, and numerous genetic and environmental aspects have been described as triggering factors. Objectives: The objective of this study was to determine the prevalence of functional alterations and thyroid autoimmunity in an urban population of Colombia. Materials and Methods: It is a cross-sectional, population-based study (n = 9,638) conducted on an urban population of Popayán-Cauca-Colombia between February 5th, 2018, to December 11th, 2021. The variables evaluated were thyrotropin (TSH), free T4 (FT4), and anti-thyroid antibodies (thyroid peroxidase antibodies: TPOAb, and thyroglobulin antibodies: TgAb). Results: TSH in men was significantly higher than in women. No differences were observed in the values of FT4, TPOAb, and TgAb (according to sex). The prevalence of normal thyroid function and subclinical hypothyroidism was significantly higher in men. The positivity of TPOAb and TgAb was 22.3% and 19.2%, respectively. TSH levels increased with age (both in men and in women). In participants with normal FT4 and negative TPOAb, the TSH was significantly higher. TSH was significantly higher in TPOAb-positive individuals and among those with TPOAb and TgAb positives, as well as in women with positive TPOAb and men with positive TPOAb and TgAb. Conclusion: In an urban population of Colombia, TSH was found to be higher than in populations of other geographical areas, especially in older individuals and in the presence of positive anti-thyroid antibodies, a high prevalence of functional alterations and thyroid autoimmunity was also found. These findings can be explained by excess iodine consumption and some environmental factors.