Endocrine Abstracts

Background: The risk of iodine-induced thyrotoxicosis is increased in patients with Graves’ disease and multi nodular goiter with thyroid autonomy. At same time, hypothyroidism can develop after iodine exposure in patients with Hashimoto’s thyroiditis. But, there are no studies about the influence of iodine containing contrast media on thyroid function in iodine excessive area. This study was done to evaluate the changes of thyroid function after coronary angiography (CAG) with/without percutaneous coronary intervention (PCI) (CAG±PCI) in Koreans with excessive iodine intake.

Methods: 56 subjects with normal thyroid function who admitted for CAG±PCI were enrolled. Levels of TSH and free thyroxine (FT₄) in serum were measured before CAG±PCI and at 1 and 12 weeks after CAG±PCI.

Results: There was no statistical significance of levels of TSH measured between before CAG±PCI and at 1 and 12 weeks after CAG±PCI. Levels of FT₄ were not changed before and after CAG±PCI, but mild increase of FT₄ was observed at 1 week after CAG±PCI. Larger amount of iodine containing contrast media for PCI did not change the thyroid function either. Among the 56 subjects, three patients were newly diagnosed as subclinical hypothyroidism at 1 week after CAG with PCI. Among the three patients, one patient remained subclinical hypothyroidism at 12 weeks after CAG with PCI.

Conclusion: There were no changes of thyroid function after CAG in Koreans with normal thyroid function. Mild elevations of FT₄ levels at 1 week after CAG±PCI was showed, but it normalised at 12 weeks after CAG±PCI. This suggests that there was no significant effect of iodine containing contrast on thyroid function.