Iodinated Contrast Media in Imaging Affects Thyroid Function

Exposure to iodinated contrast media during imaging procedures is associated with changes in thyroid function and increased risk of developing hyperthyroidism, according to a report in the January 23 issue of Archives of Internal Medicine.

Such media are a radiology mainstay, used in such procedures as CT scans and cardiac catheterization.

Connie M. Rhee, MD, and colleagues from Brigham and Women’s Hospital and Massachusetts General Hospital in Boston examined data from patients treated between January 1990 and June 2010 who did not have preexisting hyperthyroidism or hypothyroidism. Patients were matched with healthy controls, and exposure to iodinated contrast media was assessed using claims data.

A total of 178 patients with hyperthyroidism were matched with 665 healthy controls; 213 patients with hypothyroidism were matched to779 controls. The authors found that iodinated contrast media exposure was associated with incident hyperthyroidism, but no statistically significant association was found with incident hypothyroidism.

Secondary analysis indicated an association between iodinated contrast media exposure and clinical hypothyroidism as well as hyperthyroidism.

In an accompanying commentary, Elizabeth N. Pearce, MD, of Boston University School of Medicine wrote that “Rhee et al have demonstrated that a relatively large proportion of individuals who developed iodine-induced thyroid dysfunction were not known to have underlying risk factors. Therefore, patients who may be particularly unable to tolerate thyroid dysfunction, such as those with underlying unstable cardiovascular disease, are also good candidates for monitoring of thyroid function after iodine exposure.”