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Clinical Chemistry 52: 2312-2313, 2006; 10.1373/clinchem.2006.078584
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(Clinical Chemistry. 2006;52:2312-2313.)
© 2006 American Association for Clinical Chemistry, Inc.

Letters to the Editor

Pseudoparaproteinemia Related to Iomeprol Administration after Angiocardiography: Detection in the ß Fraction by Capillary Zone Electrophoresis

Pieter Vermeersch, Godelieve Mariën and Xavier Bossuyta

Laboratory Medicine, Immunology, University Hospitals Leuven, Katholieke Universiteit Leuven, Leuven, Belgium

aAddress correspondence to this author at: Herestraat 49, B-3000 Leuven, Belgium. Fax: 32-16-34-70-42; e-mail xavier.bossuyt{at}uz.kuleuven.be.


To the Editor:

Analysis of serum proteins by capillary zone electrophoresis (CZE) has become a routine method for the detection of dysproteinemias and monoclonal proteins. Detection is based on ultraviolet absorbance at 200 nm (Capillarys, Sebia) or 214 nm (Paragon 2000, Beckman Coulter), which corresponds to the absorption of peptide bonds in proteins. Compared with gel electrophoresis, CZE offers the advantage that proteins are more proportionately quantified compared with the variable dye-staining intensities exhibited by different serum proteins. A drawback of CZE, however, is the potential interference by exogenous nonprotein substances, such as radioopaque agents and antibiotics, which also absorb at these wavelengths (1).

A 5-year old girl with protein-losing enteropathy underwent routine angiocardiography 4 years after a Fontan operation for a univentricular heart, and received 6–7 mL/kg iomeprol (Iomeron). A venous blood sample was sent to the laboratory for serum protein electrophoresis. The CZE with the Capillarys showed hypogammaglobulinemia and a suspect peak in the ß-fraction (Fig. 1A ). Subsequent immunofixation (Sebia Hydrasys), however, failed to demonstrate a monoclonal protein (Fig. 1A inset). Consultation with the clinicians revealed that the blood sample had been drawn via a venous access during the angiocardiography procedure, raising the suspicion that the peak could be a result of interference from the iodinated contrast agent.


Figure 1
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  		Figure 1. Interference by iomeprol on capillary zone electrophoresis.

(A), electropherogram and immunofixation (inset) on serum from a patient who received 6–7 mL/kg iomeprol during angiocardiography. (B-C), electropherograms on serum from a control patient before (B) and after (C) adding 40 mL/L serum iomeprol.

To confirm that the interference on the Capillarys was a result of iomeprol, we enriched a control serum to give a final concentration of 28.6 g/L. On the basis of the known kinetics of the compound, this concentration was anticipated to occur in vivo. CZE revealed a peak in the middle of the ß fraction, corresponding to the location of the abnormal peak in the patient (Figs. 1B and 1CUp ).

Thus far, all reports of interference by iodinated contrast agents on CZE have been cases in which the interference was located in the {alpha}2 fraction (2)(3). In vitro, Arranz-Pena and coworkers have compared the interference by 13 different iodinated contrast agents on the Paragon by adding the different agents to control serum, and found that most agents caused a peak in the {alpha}2 fraction, but some agents (sodium-meglumine ioxaglate, ioversol, and iomeprol) caused interference in the ß-fraction(4). Here we describe a patient in whom a radioopaque agent (iomeprol) produced an interference in the ß-fraction.

Considering that the mean (SD) half-life of iomeprol in the elimination phase is 109 (20) min (drug information sheet), we evaluated the in vivo interference caused by iomeprol in 2 patients with normal renal function who underwent angiocardiography. After receiving approval from the Institutional Ethics Committee, we obtained samples before catheterization, immediately after catheterization, and at 1, 2, 4, 8, 12, and 24 h postcatheterization. For samples from both patients, CZE revealed suspect peaks in the ß fraction after angiocardiography that were clearly discernable up to 8 h after angiocardiography in the first patient and up to 4 h in the second patient. The morphology of the ß-fraction remained disturbed up to 12 h and 8 h after angiocardiography. After 24 h, no residual interference could be observed in either patient. The interference may, however, be expected to persist for more than 24 h in patients with renal dysfunction, because iomeprol is cleared via the kidneys.


Acknowledgments

We thank Peter Sinnaeve (Cardiac Unit) for providing the blood samples of the 2 patients who underwent angiocardiography with iomeprol.


References

  1. Bossuyt X. Interferences in clinical capillary zone electrophoresis of serum proteins. Electrophoresis 2004;25:1485-1487.[CrossRef][ISI][Medline] [Order article via Infotrieve]
  2. van der Watt G, Berman P. Pseudoparaproteinemia after iopamidol infusion for coronary angiography. Clin Chem 2005;51:273-274.[Free Full Text]
  3. Bossuyt X, Mewis A, Blanckaert N. Interference of radio-opaque agents in clinical capillary zone electrophoresis. Clin Chem 1999;45:129-131.[Free Full Text]
  4. Arranz-Pena ML, Gonzalez-Sagrado M, Olmos-Linares AM, Fernandez-Garcia N, Martin-Gil FJ. Interference of iodinated contrast media in serum capillary zone electrophoresis. Clin Chem 2000;46:736-737.[Free Full Text]




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Citing Articles
Right arrow Citing Articles via ISI Web of Science (1)
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Google Scholar
Right arrow Articles by Vermeersch, P.
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Right arrow Articles by Vermeersch, P.
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Related Collections
Right arrow General Clinical Chemistry
Right arrow Clinical Immunology
Right arrow Proteomics and Protein Markers
Right arrow Automation and Analytical Techniques

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