Thyroid function after hysterosalpingography using an oil-soluble iodinated contrast medium

Background. The objective of the present study was to evaluate the effect of an oil-soluble iodinated contrast medium (lipiodol) for hysterosalpingography (HSG) on thyroid function. Methods. In 214 of 528 women with infertility examined by HSG using lipiodol between 1996 and 2006 at our institution, serum free thyroxine (FT4) and thyrotropin-stimulating hormone (TSH) were measured before and several months after HSG. Results. The average age of the women was 34.5 +/- 4.6 years and their average infertility period was 2.9 +/- 2.5 years (mean +/- standard deviation). The 214 patients were divided into three groups based on the results of thyroid function before HSG: 180 in euthyroid, 28 in subclinical hypothyroidism and 13 in subclinical hyperthyroidism. The number of patients in the subclinical hypothyroidism group who developed hypothyroidism after HSG (ten of 28) was significantly higher than that of the euthyroid group (four of 180). Thyroid hormone replacement was required in three patients from the subclinical hypothyroidism group 1, 2 and 5 months after HSG. Conclusions. We conclude that thyroid function should be monitored closely after HSG using lipiodol to detect the development of hypothyroidism, particularly in patients with subclinical hypothyroidism, and TSH and FT4 measurements should be performed before HSG to identify patients at risk for hypothyroidism.