Association of socioeconomic status with iodine supply and thyroid disorders in northeast Germany.

OBJECTIVES Studies on the potential association of socioeconomic status with iodine supply and the risk for thyroid disorders from developed countries are sparse. Socioeconomic status, however, may particularly impact the efficiency of iodine prophylaxis programs, which are based on the voluntary principle. This study aims to investigate whether the socioeconomic status is cross-sectionally and longitudinally related to low urinary excretion or thyroid disorders in the population of northeast Germany. METHODS Data of the population-based Study of Health in Pomerania were used. The study population comprised 4056 adults for cross-sectional and 2860 adults for longitudinal analyses. Assessment of socioeconomic status comprised different scales of education, income, employment, and occupation. Thyroid-related outcomes included urinary iodine excretion, serum thyrotropin, and sonographically defined goiter and nodules. Statistical analyses were adjusted for confounders. RESULTS Some of the socioeconomic variables were associated with thyroid-related characteristics in cross-sectional analyses. For example, there was an overall tendency for groups with higher education and higher income to have larger thyroid volumes and an increased risk of goiter. However, most of these associations did not attain statistical significance after correcting the target p-value for multiple testing. Longitudinal analyses did not demonstrate consistent results. CONCLUSIONS Socioeconomic status neither substantially influences iodine supply nor does it have a major impact on the prevalence and incidence of thyroid deficiency-related disorders in the adult population of northeast Germany, indicating a good efficacy of the German iodine fortification program in all socioeconomic groups.