Cross sectional study on the prevalence and associated factors of iodine status in the population of Lausanne.

To assess iodine status and factors associated with iodine deficiency. Cross-sectional study conducted between 2003 and 2006 including 6,341 community dwellers, aged 35-75 years old, from a population-based sample from the city of Lausanne, Switzerland. Urinary iodine concentration (UIC) was used to assess iodine status. Iodine status was considered as adequate for UIC ≥ 100 mcg/L, mild deficiency if 50 ≤ UIC ≤ 99 mcg/L, moderate deficiency if 20 ≤ UIC ≤ 49 mcg/L, and severe deficiency if UIC < 20 mcg/L. A further categorization into adequate and deficient (UIC < 100 mcg/L) was performed. Overall, 70.5% of the participants presented with adequate iodine status, 23.0% with mild, 6.0% with moderate and 0.5% with severe iodine deficiency. After multivariable analysis, being a woman (odds ratio (95% confidence interval): 1.64 (1.45 ; 1.85)), hypertension 1.41 (1.24 ; 1.60) and increasing age (p for trend < 0.001) were associated with iodine deficiency. Conversely, increasing body mass index (p for trend < 0.001), current smoking 0.86 (0.75 ; 0.99) and thyroid hormone supplementation 0.48 (0.33 ; 0.70) were negatively associated with iodine deficiency. A positive correlation was found between UIC and urinary sodium concentration: 0.277, p < 0.001. In Lausanne, approximately one third of participants presented with iodine deficiency. Factors such as older age, being a woman or presenting with hypertension are associated with iodine deficiency, making those groups the main targets for further preventive interventions.