Low socio-economic status and familial occurrence of goitre are associated with a high prevalence of goitre.

The occurrence of goitre is dependent on genetic and environmental factors, but the associations with socio-economic and life-style factors have only been examined briefly. A cohort of 4649 participants from the general population was examined with questionnaires, thyroid ultrasonography, clinical examination and blood tests. Data were analysed in linear models and logistic regression analysis. Thyroid volume and serum thyroglobulin were closely associated with educational level with higher values in the group with the lowest levels of education (p < 0.001). The same pattern applied to thyroid multinodularity at ultrasonography (p = 0.002) and palpable goitre (p = 0.01). Physical activity in leisure time was negatively associated with thyroid enlargement (p = 0.02) and serum thyroglobulin (p < 0.001). These associations diminished markedly if adjustment was made for smoking habits, alcohol consumption and iodine intake. Familial occurrence of goitre was associated with goitre prevalence (Odds Ratio 2.5, 95% CI: 1.6-3.9), but did not confound the socio-economic associations. In conclusion, social imbalances in the occurrence of goitre were identified. These imbalances could in part be explained by differences in smoking habits and iodine intake.