Undiagnosed thyroid dysfunction, thyroid antibodies, and iodine excretion in a Mediterranean population

The prevalence of thyroid dysfunction varies in different populations. The aim of this cross-sectional study was to analyze the prevalence of undiagnosed thyroid dysfunction and thyroid antibodies and their relationship with urine iodine excretion in a representative sample of 1,124 (55.5% women; mean age: 44.8 ± 15.2 years) non-hospitalized Mediterranean adults, in Catalonia (Spain). Free thyroxine, thyroid-stimulating hormone, thyroperoxidase and thyroglobulin antibodies, and urine iodine were measured. Undiagnosed thyroid dysfunction was 5.3% (hypothyroidism 3.8%; 56.66% of these subjects were women). The total (diagnosed + undiagnosed) thyroid dysfunction was 8.9% (71.15% women). Thyroperoxidase antibodies were positive in 2.4% of men and 9.4% of women and thyroglobulin antibodies, in 1.3% of men and 3.8% of women. No differences were observed in urine iodine between groups with thyroid dysfunction and euthyroidism, or between subjects with positive or negative antibodies. In subjects over 60, undiagnosed thyroid dysfunction was 9.8% (hypothyroidism 6.9%, hyperthyroidism 3.3%; 36.36% women) and total thyroid dysfunction 13.61% (53.12% women). Women and men over 60 had similar thyroid dysfunction prevalence. Thus, aggressive case-finding should be recommended in both, over 60.