Complement-activation after intravascular contrast media: Comparison between ionic and non-ionic radiographic contrast agents

The effects of intravascular radiographic contrast media on the complementsystem were investigated in 46 patients. An ionic (sodium-/meglumine amidotrizoate, n=22) or a non-ionic (iohexol, n=24) contrast agent was applicated for an i.v. urography. The levels of the complement-compounds C1q, C3, C5 and of the C1 inhibitor were determined at the end of the infusion and 20 minutes later. In both groups we obtained a significant (p < 0.01) decrease of C3 during infusion for 10 to 15%. 20 minutes later these values were almost normalized again. Infusion of iohexol additionally caused a marked consumption of C5 and C1q (reduction to 85%), while the ionic contrast agent had no significant effect on these components. Both contrast media caused a decrease of the C1-inhibitor levels. Our results demonstrate an activation of the complement system by i.v. application of radiographic contrast media. The decrease of the C1q-level due to infusion of iohexol indicates an additional involvement of the classical activation pathway of the complement cascade. (orig.)