Interpretation and clinical significance of small monoclonal peaks in capillary electrophoresis.

BACKGROUND Although the testing mechanism and interpretation criteria for capillary electrophoresis differ from those for gel-based electrophoresis, there are not that many reports on the efficacy of capillary electrophoresis. MATERIALS AND METHODS We performed a retrospective analysis, using the Laboratory Information System (LIS) to review a total of 163 capillary electrophoresis results from 117 different patients treated in our hospital between March and August 2012. Capillary electrophoresis was performed on capillary2 (Sebia, Lysse, France). RESULTS Among the patients' group, 4 patients presented very small M-peaks in capillary electrophoresis. By using the zoom function in capillary electrophoresis, two of them were confirmed to have monoclonality, but the remaining two required reconfirmation in gel electrophoresis, leading to confirmation of a discrete monoclonal band. CONCLUSION In this study, we found that small peaks in capillary electrophoresis accompanying a skewed K/L ratio deserve particular attention as they can grow into larger peaks within a few months. We suggest that any trivial M-peak in capillary electrophoresis should not be overlooked and that a combination of platform tests such as gel electrophoresis or FLC assay be implemented in order to confirm monoclonality.