Plasma leukotriene C4 and reactions to contrast media

Forty-five patients were randomly divided into three groups of 15 and within each group patients were given iothalamate, iopamidol or ioxaglate intravenously during radiological investigations. The plasma leukotriene C4 level was measured before and 30 s and 3 min after the administration of the respective contrast media. In patients demonstrating non-idiosyncratic contrast reactions, a consistent decrease in plasma leukotriene concentration was noted at both 30 s and 3 min following the administration of all three contrast media. A statistically significant decrease in plasma leukotriene occurred at 30 s with ioxaglate, but not with the other two agents. In the limited number of patients who experienced idiosyncratic reactions, the decrease in plasma leukotriene concentration was less apparent. This decrease in plasma leukotriene concentration has been attributed to changes in plasma volume following administration of hyperosmolar contrast media. The inability to demonstrate an increase in plasma leukotriene levels following the administration of both conventional and new, low-osmolar radiographic contrast media supports the cumulative evidence against an allergic mechanism in the majority of non-idiosyncratic and some idiosyncratic contrast reactions.