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

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 anti-thyroperoxide 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 microg/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 anti-thyroglobulin, 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.

• Authors: F Azizi, M Hedayati, M Rahmani, R Sheikholeslam, S Allahverdian, N Salarkia
• Journal: Journal of endocrinological investigation (J Endocrinol Invest) Vol. 28 Issue 1 Pg. 23-9 (Jan 2005) ISSN: 0391-4097 [Print] Italy
• PMID: 15816367 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Thyroid Hormones
• Thyroglobulin
• Iodine
• Peroxidases

Topics

• Adolescent
• Adult
• Aging (metabolism)
• Child
• Data Collection
• Endemic Diseases
• Female
• Goiter (drug therapy, epidemiology)
• Humans
• Hyperthyroidism (chemically induced, epidemiology)
• Iodine (adverse effects, deficiency, therapeutic use)
• Iran (epidemiology)
• Male
• Middle Aged
• Peroxidases (blood)
• Population
• Quality Control
• Thyroglobulin (metabolism)
• Thyroid Hormones (blood)