The influence on thyroid function of two iodine-containing radiological contrast media

The aim of this study was to establish the effects of two iodine-containing radiological contrast media (ioxaglate and diatrizoate) on plasma iodide, thyroid hormones and TSH in a group of 20 subjects (8 females, 12 males). The following were evaluated two, eight and 30 days after administration of the drugs: plasma iodide, T4, T3, rT3, FT41, TSH before and after TRH (250 micrograms IV). 131I uptake was measured before the media were given and 30 days afterwards. The results were compared at the different times during the investigation using Wilcoxon's signed ranking test for non-parametric variables. Plasma iodide was found to be above the normal range two to eight days after ioxaglate and two to eight and 30 days after diatrizoate. After ioxaglate, rT3 was increased at eight days and T3 at 30 days. 131I uptake remained low after the 30th day. After diatrizoate, T4 was decreased on the second day and FT41 was low, on the eighth and 30th day. All figures represent statistically significant but nevertheless minor variations of the initial value of each parameter. In conclusion, although ioxaglate and diatrizoate lead to variations in plasma thyroid hormone levels, they are of little importance.