Cardiac catheterization dye does not affect serum thyroid hormone concentrations or TSH secretion.

The iodinated contrast agents used in oral cholecystography impair peripheral iodothyronine-5'-deiodinase activity, resulting in a transient decrease in serum 3,5,3'-triiodothyronine (triiodothyronine, T3) and in increases in serum 3,3',5'-triiodothyronine (reverse T3, rT3) and thyroxine (T4) concentrations. A related iodinated contrast agent, diatrizoate, is employed in coronary angiography. The effect of diatrizoate (Renografin-76) on serum T4, T3, rT3, and thyroid stimulating hormone (thyrotropin, TSH) concentrations and the TSH and T3 responses to thyrotropin releasing hormone (TRH) were evaluated in seven euthyroid patients before and on the fifth day following coronary angiography. No significant changes were observed. Thus, diatrizoate, in contrast to the oral cholecystographic agents, appears to have little or no clinically important effect on thyroid hormone metabolism in man.