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Invited Commentary
Jan 23, 2012

Iodine-Induced Thyroid Dysfunction: Comment on “Association Between Iodinated Contrast Media Exposure and Incident Hyperthyroidism and Hypothyroidism”

Author Affiliations

Author Affiliation: Section of Endocrinology, Diabetes, and Nutrition, Boston University School of Medicine, Boston, Massachusetts.

Arch Intern Med. 2012;172(2):159-161. doi:10.1001/archinternmed.2011.1396

In this issue of the Archives, Rhee et al1 report the findings of a nested case-control study examining associations between exposure to iodinated radiologic contrast media and development of incident thyroid dysfunction. They describe significant associations between contrast exposure and the development of hyperthyroidism. While no overall association exists between contrast exposure and all forms of hypothyroidism, an association was noted when cases were restricted to those with overt hypothyroidism. There was also an association between iodinated contrast media and incident hypothyroidism when the analysis was restricted to cases that occurred within 180 days of exposure, likely related to the transitory nature of iodine-induced hypothyroidism. These data represent an important contribution to our knowledge about a clinically relevant and understudied area. Strengths of the study include the large number of cases and controls, rigorous case definitions, and adjustment for multiple potential confounders. The study was limited by its retrospective design, by variability in intervals between thyroid function testing, and by the limited availability of peripheral thyroid hormone measurements. The study was conducted in Boston, Massachusetts, which is considered an iodine-sufficient area, and results may not be generalizable to parts of the world with insufficient dietary iodine intake.

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