Complement abnormalities during contrast media procedures.

Complement changes following the administration of the two most commonly used intravascular contrast media (CM) diatrizoate and iothalmate were studied in 26 patients by measuring complement component C3 levels and the total hemolytic function. Blood from these patients was obtained in plastic tubes containing 10 mM ethylene diamine tetra-acetic acid (EDTA) prior to and 15 min after contrast media infusion. In thirteen patients who received iothalamate a 28% drop in C3 concentration and a 19% change in total hemolytic complement was seen. In the second group of thirteen patients diatrizoate caused a 20% C3 decrease and a 15% reduction in total hemolytic complement. Since iothalamate is a hyperosmolar and hyperviscous solution compared to diatrizoate, it is likely that these factors are responsible for changes in complement level which may present potential risk to patients with depressed immunologic status. This study suggests that screening of patients for their total complement profile may provide useful information in minimizing adverse reactions to contrast material.