Laboratory Medicine vol. 42, no. 10, pp. 602 - 606
In the detection of monoclonal proteins using capillary electrophoresis (CE), several problems have been described, especially for small amounts of paraprotein, light chain (LC) disease, and cases associated with contrast interference. In this report, we describe 3 unusual cases that showed false-positive peaks due to radiologic contrast interference and the escape of monoclonal LC in CE. In these cases questionable for monoclonal components, conventional gel tests and free LC assays could be helpful to confirm monoclonal gammopathy. Therefore, multiple methodological modalities should be combined for diagnosing and monitoring plasma cell neoplasms and related disorders.