Thyroid hormone therapy in a population cohort over two decades indicates persistent overtreatment

Objective: Thyroid hormones (THs) are among the most prescribed medications worldwide, and regular monitoring of thyroid function is required to ensure optimal management. Both over- and undertreatment with THs is associated with health risks, including increased cardiovascular morbidity and mortality, as well as higher socioeconomic costs. We investigated how changes in treatment concepts and guideline recommendations over two decades have influenced the frequency and quality of TH treatment in a high-income country. Methods: Data from 7,711 participants in the German population-based Heinz Nixdorf Recall (HNR) study were descriptively analyzed to assess the prevalence of reported thyroid disease, TH therapy, and thyrotropin (TSH) concentrations measured by immunoassay over the period 2000-2023. The mean age differed from 53.8 ± 15.1 years to 68.7 ± 7.3 years (45.8-49.6% males). Descriptive analyses were also stratified by age, sex, and educational attainment. Results: The prevalence of reported thyroid disease remained stable throughout the study period, whereas TH prescription increased from 9.2 to 15.3% over two decades. TH therapy was more common among women and older participants. Compared with individuals without thyroid disease or those with thyroid disease not treated with THs, median TSH concentrations were lower in participants receiving TH therapy, with the greatest reduction observed in older individuals. At study baseline, 35% of participants with TSH concentrations