Effects of five different contrast agents on serum complement and calcium levels after excretory urography

The effects of five different radiocontrast media (RCM) molecules on the complement system were investigated in vivo in human patients undergoing excretory urography. Ioxitalamic, ioxaglic, Na-diatrizoic, Na-Mg diatrizoic acids, and iopamidol were randomly used in 61 patients. Proteins involved in classic or alternate pathway, RCM plasma concentration, total and ionized calcium levels, and osmolarity were analysed before (TO), 90 sec (T1), and 30 min (T2) after RCM injection. Proteins of the classic and alternate pathways of complement activation were significantly decreased at T1, at a range of 7% to 17%. However, these impairments were rapidly reversible, since no significant variations, as compared with TO values, were observed at T2, except after use of ioxaglic acid. A significant decrease in total serum calcium level from 91 to 83 mg/L was observed at T1 for all RCM tested. However, a tendency toward improvement at T2 was noted. Ionized calcium serum levels were also significantly decreased at T1, except when ioxaglic acid and iopamidol were used. These changes were reversible at T2 for all RCM except ioxitalamic acid. The magnitude of the variation of complement protein levels and of calcium levels observed in vivo was related to the nature of the molecule tested and was of a decreasing order after injection of ioxitalamic acid, Na-Mg diatrizoic acid, Na-diatrizoic acid, iopamidol, and ioxaglic acid. There was no modification of plasma osmolarity after RCM injection.