Short-term effect of iodine contrast medium on thyroid function: a prospective cohort study

Excess iodine intake due to iodinated contrast media (ICM) infusion during medical examinations is considered as a potential cause of thyroid abnormalities. However, the short-term effects of ICM exposure on patients in a Chinese population are not well elucidated.

In total, 200 patients who received intravenous ICM were enrolled, and their thyroid function was determined before ICM exposure (baseline) as well as 1 week and 1 month after the ICM infusion. The relationship between the peak urinary iodine concentration (UIC) and the contrast agent (CA) dose was then investigated. Three months after ICM exposure, the patients who developed thyroid dysfunction within 1 month of ICM exposure were followed up.

This study included 125 males and 75 females, with a mean age of 56.56 ± 13.89 years old and an average CA dose of 26.93 ± 8.35 g. Patients with thyroid nodules had an increased risk of subclinical hyperthyroidism (OR = 2.1491, 95% CI: 1.0335-71.1880, p = 0.0465). Additionally, the urinary iodine level (1658.37 ± 527.47 μg/L) peaked at 1 week after ICM exposure, and the peak level was weakly positively correlated with free thyroxine (FT4) level (r = 0.1531, p = 0.0317). Meanwhile, CA dose weakly negatively correlated with anti-thyroid peroxidase antibody (TPOAb) (r=-0.2077, p = 0.0035). The follow-up results at 3 months after ICM exposure showed that the newly developed abnormal thyroid function within 1 month of ICM exposure had mostly returned to normal.

Patients with thyroid nodules had an increased risk of subclinical hyperthyroidism 1 month after iodine contrast imaging. The effect was transient, and most patients self-recovered without any intervention.