Changes in serum iodine concentration, urinary iodine excretion and thyroid function after hysterosalpingography using an oil-soluble iodinated contrast medium (lipiodol).

Objective: Reports of hypothyroidism after hysterosalpingography (HSG) using lipiodol are emerging. The present study was designed to investigate the changes in serum iodine concentration (SIC), urinary iodine concentration/creatinine excretion (UI/Cr), and thyroid function before and after HSG using lipiodol.

Methods: The prospective observation study included 22 infertile euthyroid women with no previous history of thyroid disease. All underwent HSG between April 2007 and August 2008 at our institution. We examined SIC, UI/Cr, and thyroid function before HSG, and at 4, 8, 12, and 24 weeks, and 9-12 months after HSG.

Results: The median value of SIC and UI/Cr peaked at 4 weeks after HSG and remained at significantly high levels at 8, 12, and 24 weeks post-HSG compared with pre-HSG. In sync with the increase of iodine, the mean level of TSH significantly increased at 4, 8, 12, and 24 weeks post-HSG compared with pre-HSG. After 24 weeks, differences in SIC, UI/Cr, and TSH levels before and after HSG became nonsignificant. The mean value of free triiodothyronine and free thyroxine showed no significant difference at any of the time points compared with pre-HSG. Three cases (13.6%) showed transient high TSH (>5 μIU/L) with normal thyroid hormones at 4 or 8 weeks after HSG.

Conclusion: Thyroid monitoring should be conducted in the first 4-8 weeks after HSG using lipiodol and attention to thyroid dysfunction should be paid for up to 6 months after the procedure due to the possibility of excess iodine.