title: 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.affiliation: Endocrine Research Center, Shaheed Beheshti University of Medical Sciences, Tehran, Islamic Republic of Iran. iced@erc-iran.com
authors.forename: F
authors.initials: F
authors.lastname: Azizi
authors.forename: M
authors.initials: M
authors.lastname: Hedayati
authors.forename: M
authors.initials: M
authors.lastname: Rahmani
authors.forename: R
authors.initials: R
authors.lastname: Sheikholeslam
authors.forename: S
authors.initials: S
authors.lastname: Allahverdian
authors.forename: N
authors.initials: N
authors.lastname: Salarkia
mesh_terms: D000293:Adolescent; D000328:Adult; D000375:Aging / Q000378:metabolism; D002648:Child; D003625:Data Collection; D019353:Endemic Diseases; D005260:Female; D006042:Goiter / Q000188:drug therapy / Q000453:epidemiology; D006801:Humans; D006980:Hyperthyroidism / Q000139:chemically induced* / Q000453:epidemiology*; D007455:Iodine / Q000009:adverse effects* / Q000172:deficiency / Q000627:therapeutic use; D007492:Iran / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D010544:Peroxidases / Q000097:blood; D011153:Population; D011786:Quality Control; D013954:Thyroglobulin / Q000378:metabolism; D013963:Thyroid Hormones / Q000097:blood
chemical_list: D013963:Thyroid Hormones; D013954:Thyroglobulin; D007455:Iodine; D010544:Peroxidases