ESPE Abstracts

Introduction: Hysterosalpingography using oil-soluble iodinated contrast medium (ethiodized oil; Lipiodol) is a common examination for patients with infertility. Lipiodol remains in the body long after the examination, and there are some reports suggesting that Lipiodol induces thyroid dysfunction not only to the mother but also the fetus and the newborn. However, since there are no known mouse models of Lipiodol-induced thyroid dysfunction, we examined the influence of Lipiodol on child’s thyroid function in mice by administering Lipiodol to its mother.

Materials and methods: 12 week-old ICR female mice were intraperitoneally administered with Lipiodol once before mating or during pregnancy or after delivery, and the thyroid uptake rate of I-131 (74 kBq/mouse) in their newborn mice was examined 24 hours after oral administration of I-131. The dose of Lipiodol used was either equivalent to that used in humans (0.2 μl/g BW, iodine amount=96 μg/g BW) or its 1/2 or 1/10 amount. Lipiodol was diluted with corn oil, and all were set to a total of 10 μL/g BW. The same volume of corn oil was used as a control. When the offspring mice reached 4 weeks of age, serum TSH and FT4 were measured by ELISA method. The number of mice in each experiment was 6 or more.

Results and discussion: When 0.2 μL/g BW Lipiodol or its 1/2, 1/10 amount were administered intraperitoneally before pregnancy (5 days before gestation), thyroid uptake rate of I-131 in 5 day old infants was decreased to 24.4, 24.0 and 58.7% compared to control, respectively. When 0.2 μl/g BW of Lipiodol was administered to mice during pregnancy (10th gestation) or immediately after birth, thyroid uptake rate of I-131 in 5 day old infant was decreased to 5.8 and 2.4% compared to control, respectively. There was no change in TSH level in infant mice at 4 weeks of age, but a significant decrease in FT4 was observed. This result suggests that the amount of Lipiodol used in examinations such as hysterosalpingography should be kept as little as possible, and that thyroid function in children born after examinations using Lipiodol needs to be carefully observed.