Radiographic contrast media infusions: Measurement of histamine, complement, and fibrin split products and correlation with clinical parameters

To further an understanding of the effects of radiographic contrast media (RCM) infusions, 43 patients underwent clinical evaluation, including allergy history and skin testing, at least 48 hr before receiving a bolus of Renografin-60 (meglumine diatrizoate [52] and sodium diatrizoate [8]) for intravenous pyelography. Venous plasma samples were obtained serially before and at 2, 4, 10, 30, and 60 min after the infusion. Each sample was assayed for histamine by isotopic enzyme assay, for complement by total hemolytic activity, and for fibrin split products by radioimmunoassay. Immediate generalized reactions occurred in 6 of the patients. Each of the 43 patients had a change in at least 1 of the mediators measured. Plasma histamine rose in 40% of the patients (mean, 3.1 ± 1.62 ng/ml). Plasma complement hemolytic activity decreased in 63% (mean, 29 ± 19%). Fibrin split products were detected in 41%. In comparing the 6 patients who experienced reactions to the 37 who did not, there were no statistically significant differences in rise in plasma histamine, decrease in complement activity, presence of fibrin split products, personal history of allergy, prior exposure or reaction to RCM, skin tests to RCM, and histamine or saline. Although histamine levels, complement activity, and fibrin split products changed in a substantial number of patients undergoing RCM infusions, these changes did not correlate with immediate generalized reactions or with the previously described clinical parameters. It is probable that other modulating factors play significant roles in determining whether or not a reaction occurs.