The presence of iodinated radio-opaque contrast media infused for imaging studies may result in an apparent restriction zone on capillary zone electropheresis. Demonstration of certain laboratory features plus the clinical history can usually resolve the problem.
Pathogenesis: Arranz-Pena et al reported evidence that the contrast media binds to proteins. The contrast media also absorbs light at the same wavelength used to detect protein (over range of 214 to 244 nm).
Features:
(1) zone of restriction seen on capillary zone electrophoresis in the alpha-2 or beta region
(2) zone of restriction is not seen on agarose gel or immunofixation
(3) zone not removed by antibodies to light or heavy chains
(4) zone removed by activated charcoal (Arranz-Pena et al) or a desalting (Blessum et al) procedure
(5) history of radio-opaque contrast media administration in preceding 2-6 days
