The Effect of Voluntary Iodine Prophylaxis in a Small Rural Community: The Pescopagano Survey 15 Years Later
Department of Endocrinology and Metabolism, University of Pisa, via Paradisa 2, 56100 Pisa, Italy. .The Journal of Clinical Endocrinology and Metabolism (Impact Factor: 6.21). 03/2013; 98(3):1031-9. DOI: 10.1210/jc.2012-2960
Context: Iodine deficiency disorders are a major public health problem, and programs have been implemented to improve iodine nutrition. Objective: The objective of the study was to verify the effects of voluntary iodine prophylaxis in a small rural community (Pescopagano, Italy). Design: The design of the study was the evaluation of the prevalence of thyroid disorders 15 years after a previous survey conducted before iodine prophylaxis. Setting: The setting for this study was a general community survey. Participants: One thousand one hundred forty-eight residents were examined in 2010 and 1411 in 1995. Results: In 2010, 757 of 1148 subjects (65.9%) routinely used iodized salt, urinary iodine excretion being significantly higher than in 1955 (median 98.0 μg/L, vs 55.0 μg/L, P < .0001). The prevalence of goiter was lower in 2010 than in 1995 (25.8% vs 46.1%, P < .0001), mainly due to the reduction of diffuse goiter (10.3% vs 34.0%, P < .0001). In 2010 vs 1995, thyroid autonomy in subjects younger than 45 years old (3 of 579, 0.5% vs 25 of 1010, 2.5% P = .004) and nonautoimmune hyperthyroidism in subjects older than 45 years old (8 of 569, 1.4% vs 18 of 401, 4.5%, P = .03) were less frequent. The prevalence of hypothyroidism was higher in 2010 vs 1995 (5.0% vs 2.8%, P = .005), mainly because of an increased frequency of subclinical hypothyroidism in subjects younger than 15 years old (7 of 83, 8.4% vs 0 of 419, 0.0%, P < .0001). Accordingly, serum thyroid autoantibodies (19.5% vs 12.6%; P < .0001) and Hashimoto's thyroiditis (14.5% vs 3.5%; P < .0001) were more frequent in 2010 than in 1995. Conclusions: In the present work, the role of voluntary iodine prophylaxis was assessed in a small rural community relatively segregated, in which genetic and other environmental factors have not substantially changed between the 2 surveys. Iodine intake strongly affected the pattern of thyroid diseases, but the benefits of correcting iodine deficiency (decreased prevalence of goiter and thyroid autonomy in younger subjects and reduced frequency of nonautoimmune hyperthyroidism in older subjects) far outweighs the risk of development of thyroid autoimmunity and mild hypothyroidism in youngsters.
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ABSTRACT: To provide information on the role of the essential trace element selenium, which enables appropriate thyroid hormone synthesis, secretion, and metabolism, and to discuss supplementation with various selenium compounds, which prevent thyroid diseases such as goiter and exert beneficial effects in thyroid autoimmune diseases. Selenium administration in both autoimmune thyroiditis (M. Hashimoto) and mild Graves' disease improves clinical scores and well-being of patients and reduces autoimmune antibody titres in several prospective, placebo-controlled supplementation studies. Adequate nutritional supply of selenium, together with the two other essential trace elements iodine and iron, is required for a healthy thyroid during development and adolescence, as well as in the adult and aging populations.
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ABSTRACT: Context:The mechanisms linking thyroid autoimmunity and iodine use in humans are unknown.Objective:To correlate iodine intake, thyroid autoimmunity, and recognition of thyroglobulin (Tg) epitopes after implementation of iodine prophylaxis.Setting:General community living in an Italian village.Main Outcome Measures:Thyroglobulin autoantibodies (TgAb), thyroperoxidase autoantibodies (TPOAb), and urinary iodine excretion were assessed in 906 iodized salt users (IS-users) and 389 nonusers (IS-nonusers). Ultrasound (US) was performed to identify thyroid hypoechogenicity, suggestive of Hashimoto thyroiditis (HT). TgAb epitope pattern in 16 IS-users and 17 IS-nonusers was evaluated by an inhibition binding assay to Tg, using human monoclonal TgAb-Fab directed to A, B, C, and D epitopes on Tg.Results:Median urinary iodine excretion was slightly higher in IS-users than in IS-nonusers (112.0 μ g/L vs 86.5 μ g/L; P < .01). TgAb, and not TPOAb, was more frequent in IS-users (18.9% vs 13.6%, P = .02). HT-US was found in 87 subjects, among whom both positive TgAb (58.4% vs 31.8%, P = .03) and TPOAb (61.5% vs 45.4%. P = .04) were more frequent in IS-users. In this group significantly higher serum levels of TgAb (median 108 U/mL vs 30 U/mL; P = .02), but not of TPOAb, were present. Iodized salt use had no effect on the 1208 non HT-US subjects. TgAb directed to the epitope B of Tg were more frequent in IS-users than in IS-nonusers (27.5% vs 3.0%, P = .047).Conclusions:Iodine-induced thyroid autoimmunity is related to TgAb and the unmasking of a cryptic epitope on Tg contributes to this relationship in humans.
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ABSTRACT: To assess the individual thyroid volume changes after the mandatory nationwide iodine fortification program in two Danish areas with different iodine intake at baseline (Copenhagen, mild iodine deficiency (ID) and Aalborg, moderate ID). A longitudinal population-based study (DanThyr). We examined 2,465 adults before (1997) and after (2008) the Danish iodine fortification of salt (2000). Ultrasonography was performed by the same sonographers using the same equipment, after controlling performances. Participants treated for thyroid disease were excluded from analyses. Overall, median thyroid volume had increased in Copenhagen (11.8 to 12.2 mL, p=0.001) and decreased in Aalborg, although not significantly (13.3 to 13.1 mL p=0.07) during the 11-years of follow-up. IN BOTH REGIONS THERE WAS AN AGE-RELATED TREND IN INDIVIDUAL CHANGES IN THYROID VOLUME FROM BASELINE TO FOLLOW-UP; THYROID VOLUME INCREASED IN WOMEN 40 YEARS OF AGE AND DECREASED IN WOMEN 40 YEARS OF AGE.IN A MULTIVARIATE REGRESSION MODEL, HIGHER AGE AT ENTRY WAS A PREDICTOR (P0.05) FOR THYROID VOLUME DECREASE 20% DURING THE FOLLOW-UP PERIOD (WOMEN AGED 40-45 YEARS: Odds ratio (OR) 4.3 (95% confidence interval (CI), 2.2-8.2); women aged 60-65 years: 5.8 (2.9-11.6)) and individuals of higher age were also less likely to have an increase in thyroid volume (women aged 40-45 years: OR 0.2 (0.1-0.3); woman aged 60-65: OR 0.3(0.2-0.4)) CONCLUSIONS: Age dependent differences in thyroid volume and enlargement had levelled out after the Danish iodization program. Thus, the previously observed increase in thyroid volume with age may have been caused by iodine deficiency.
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