FREE NEJM E-TOC    HOME   |   SUBSCRIBE   |   CURRENT ISSUE   |   PAST ISSUES   |   COLLECTIONS   |   Search Term  Advanced Search

Sign in | Get NEJM's E-Mail Table of Contents — Free | Subscribe

Previous Volume 354:2783-2793 June 29, 2006 Number 26 Next

	Full Text PDF PDA Full Text PowerPoint Slide Set Editorial by Utiger, R. D. Add to Personal Archive Add to Citation Manager Notify a Friend E-mail When Cited E-mail When Letters Appear PubMed Citation

ABSTRACT

Background Iodine is an essential component of thyroid hormones; either low or high intake may lead to thyroid disease. We observed an increase in the prevalence of overt hypothyroidism, subclinical hypothyroidism, and autoimmune thyroiditis with increasing iodine intake in China in cohorts from three regions with different levels of iodine intake: mildly deficient (median urinary iodine excretion, 84 µg per liter), more than adequate (median, 243 µg per liter), and excessive (median, 651 µg per liter). Participants enrolled in a baseline study in 1999, and during the five-year follow-up through 2004, we examined the effect of regional differences in iodine intake on the incidence of thyroid disease.

Methods Of the 3761 unselected subjects who were enrolled at baseline, 3018 (80.2 percent) participated in this follow-up study. Levels of thyroid hormones and thyroid autoantibodies in serum, and iodine in urine, were measured and B-mode ultrasonography of the thyroid was performed at baseline and follow-up.

Results Among subjects with mildly deficient iodine intake, those with more than adequate intake, and those with excessive intake, the cumulative incidence of overt hypothyroidism was 0.2 percent, 0.5 percent, and 0.3 percent, respectively; that of subclinical hypothyroidism, 0.2 percent, 2.6 percent, and 2.9 percent, respectively; and that of autoimmune thyroiditis, 0.2 percent, 1.0 percent, and 1.3 percent, respectively. Among subjects with euthyroidism and antithyroid antibodies at baseline, the five-year incidence of elevated serum thyrotropin levels was greater among those with more than adequate or excessive iodine intake than among those with mildly deficient iodine intake. A baseline serum thyrotropin level of 1.0 to 1.9 mIU per liter was associated with the lowest subsequent incidence of abnormal thyroid function.

Conclusions More than adequate or excessive iodine intake may lead to hypothyroidism and autoimmune thyroiditis.

Source Information

From the Department of Endocrinology and Metabolism (W.T., Z.S., H.G., Y.J., F.H.) and the Institute of Endocrinology (X.T., Y.L., D.T., X.Y., C.F., W.C., F.Y., H.D., Y.Y., J.L., Y.C., D.Z., X.S., J.M., X.G., R.Y., Y.T., W.W., T.G., C.L.), First Affiliated Hospital, China Medical University, Shengyang, China.

Address reprint requests to Dr. Weiping Teng at the Department of Endocrinology and Metabolism, First Affiliated Hospital, China Medical University, No. 155 Nanjing Bei St., Heping District, Shengyang, China, or at twpendocrine{at}yahoo.com.cn.

Full Text of this Article

This article has been cited by other articles:

• Zimmermann, M. B. (2009). Iodine Deficiency. Endocr. Rev. 30: 376-408 [Abstract] [Full Text]  
• Guan, H., Ji, M., Bao, R., Yu, H., Wang, Y., Hou, P., Zhang, Y., Shan, Z., Teng, W., Xing, M. (2009). Association of High Iodine Intake with the T1799A BRAF Mutation in Papillary Thyroid Cancer. J. Clin. Endocrinol. Metab. 94: 1612-1617 [Abstract] [Full Text]  
• Volzke, H., Robinson, D. M., Spielhagen, T., Nauck, M., Obst, A., Ewert, R., Wolff, B., Wallaschofski, H., Felix, S. B., Dorr, M. (2009). Are serum thyrotropin levels within the reference range associated with endothelial function?. Eur Heart J 30: 217-224 [Abstract] [Full Text]  
• Bougneres, P., Valleron, A.-J. (2008). Causes of early-onset type 1 diabetes: toward data-driven environmental approaches. JEM 205: 2953-2957 [Abstract] [Full Text]  
• Camargo, R. Y A, Tomimori, E. K, Neves, S. C, G S Rubio, I., Galrao, A. L., Knobel, M., Medeiros-Neto, G. (2008). Thyroid and the environment: exposure to excessive nutritional iodine increases the prevalence of thyroid disorders in Sao Paulo, Brazil. Eur J Endocrinol 159: 293-299 [Abstract] [Full Text]  
• Dorr, M., Empen, K., Robinson, D. M, Wallaschofski, H., Felix, S. B, Volzke, H. (2008). The association of thyroid function with carotid artery plaque burden and strokes in a population-based sample from a previously iodine-deficient area. Eur J Endocrinol 159: 145-152 [Abstract] [Full Text]  
• Li, Y., Teng, D., Shan, Z., Teng, X., Guan, H., Yu, X., Fan, C., Chong, W., Yang, F., Dai, H., Gu, X., Yu, Y., Mao, J., Zhao, D., Li, J., Chen, Y., Yang, R., Li, C., Teng, W. (2008). Antithyroperoxidase and Antithyroglobulin Antibodies in a Five-Year Follow-Up Survey of Populations with Different Iodine Intakes. J. Clin. Endocrinol. Metab. 93: 1751-1757 [Abstract] [Full Text]  
• Karmisholt, J., Laurberg, P. (2008). Serum TSH and serum thyroid peroxidase antibody fluctuate in parallel and high urinary iodine excretion predicts subsequent thyroid failure in a 1-year study of patients with untreated subclinical hypothyroidism. Eur J Endocrinol 158: 209-215 [Abstract] [Full Text]  
• Biondi, B., Cooper, D. S. (2008). The Clinical Significance of Subclinical Thyroid Dysfunction. Endocr. Rev. 29: 76-131 [Abstract] [Full Text]  
• Poncin, S., Gerard, A.-C., Boucquey, M., Senou, M., Calderon, P. B., Knoops, B., Lengele, B., Many, M.-C., Colin, I. M. (2008). Oxidative Stress in the Thyroid Gland: From Harmlessness to Hazard Depending on the Iodine Content. Endocrinology 149: 424-433 [Abstract] [Full Text]  
• Bulow Pedersen, I., Laurberg, P., Knudsen, N., Jorgensen, T., Perrild, H., Ovesen, L., Rasmussen, L. B. (2007). An Increased Incidence of Overt Hypothyroidism after Iodine Fortification of Salt in Denmark: A Prospective Population Study. J. Clin. Endocrinol. Metab. 92: 3122-3127 [Abstract] [Full Text]  
• Yang, F., Shan, Z., Teng, X., Li, Y., Guan, H., Chong, W., Teng, D., Yu, X., Fan, C., Dai, H., Yu, Y., Yang, R., Li, J., Chen, Y., Zhao, D., Mao, J., Teng, W. (2007). Chronic iodine excess does not increase the incidence of hyperthyroidism: a prospective community-based epidemiological survey in China. Eur J Endocrinol 156: 403-408 [Abstract] [Full Text]  
• Wijaya-Erhardt, M., Untoro, J., Karyadi, E., Wibowo, L., Gross, R. (2007). Efficacy of daily and weekly multiple micronutrient food-like tablets for the correction of iodine deficiency in Indonesian males aged 6-12 mo. Am. J. Clin. Nutr. 85: 137-143 [Abstract] [Full Text]  
• Zimmermann, M. B., de Benoist, B., Corigliano, S., Jooste, P. L., Molinari, L., Moosa, K., Pretell, E. A., Al-Dallal, Z. S., Wei, Y., Zu-Pei, C., Torresani, T. (2006). Assessment of Iodine Status Using Dried Blood Spot Thyroglobulin: Development of Reference Material and Establishment of an International Reference Range in Iodine-Sufficient Children. J. Clin. Endocrinol. Metab. 91: 4881-4887 [Abstract] [Full Text]  
• (2006). Lucina. Arch. Dis. Child. 91: 1048-1048 [Full Text]  
• Pearce, E. N., Hollowell, J. G. Jr., Morreale de Escobar, G., Escobar del Rey, F., Utiger, R. D. (2006). Iodine Nutrition -- More Is Better. NEJM 355: 1500-1501 [Full Text]  
• Tonks, A. (2006). What's new in the other general journals. BMJ 333: 90-91 [Full Text]  
• Utiger, R. D. (2006). Iodine nutrition--more is better.. NEJM 354: 2819-2821 [Full Text]