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Reappraisal of the risk of iodine-induced hyperthyroidism: An epidemiological population survey

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Abstract

The occurrence of iodine-induced hyperthyroidism (IIH) has been reported after iodine supplementation from clinics and hospitals, but not following an epidemiologic survey. We studied the prevalence of thyroid derangement in a population following iodine supplementation. One yr after more than 75% of the population had been consuming 40 ppm iodized salt; information regarding history of endemic goiter and iodized salt production, distribution, consumption and monitoring were collected in four cities of the Islamic Republic of Iran. A total of 6048 subjects were randomly selected. All subjects were assessed for size of goiter, and urinary iodine and serum T4, T3, TSH, anti-thyroglobulin and antithyroperoxide were measured. Before iodine supplementation, all four cities were areas of endemic goiter. The rate of household consumption of iodized salt was 50, 75 and 90% in 1994, 1995 and 1996, respectively. Ninety-one percent of the salt samples contained 15–55 ppm iodide. Total goiter rate was 57, 62 and 68%; median urinary iodine was 188, 197 and 190 μg/l in the age groups of 6–18, 19–40 and >40 yr, respectively. Prevalence of clinical and subclinical hyperthyroidism was 0.34 and 0.41 and those of clinical and subclinical hypothyroidism were 0.51 and 1.07%, respectively. Nine point eight and 18% in the 19–40 yr age group and 17.6 and 25.6% in >40 yr old subjects had positive anti-thyroperoxidase and antithyroglobulin, respectively. This systemic epidemiologic study in an iodine deficient population showed that, following a well-executed iodine supplementation program, the occurrence of IIH is rare.

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Authors and Affiliations

  1. Endocrine Research Center, Shaheed Beheshti University of Medical Sciences, P.O. Box 19395-4763, Tehran, I.R. Iran

    F. Azizi, M. Hedayati & M. Rahmani

  2. Department of Nutrition, Ministry of Health and Medical Education, Tehran, Islamic Republic of Iran

    R. Sheikholeslam & N. Salarkia

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  1. F. Azizi
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  2. M. Hedayati
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  3. M. Rahmani
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  4. R. Sheikholeslam
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Correspondence to F. Azizi.

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Azizi, F., Hedayati, M., Rahmani, M. et al. Reappraisal of the risk of iodine-induced hyperthyroidism: An epidemiological population survey. J Endocrinol Invest 28, 23–29 (2005). https://doi.org/10.1007/BF03345525

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