Objective: Monoclonal protein (MP) exists in various diseases, and capillary electrophoresis (CE) has been widely used to detect MP. However, there is not much research on the application value of MP in the differential diagnosis of monoclonal gammopathies. This study aimed to explore MP's cutoff value for the differential diagnosis of multiple myeloma (MM) and other monoclonal gammopathies (MGs).
Methods: A retrospective analysis of 8167 cases was conducted. Serum MP was detected by CE, and the patients' clinical information was collected from the clinical database of our hospital.
Results: 985 cases had MP with high peaks, and 91.1% were diagnosed with malignant diseases. The MP showed small peaks in 471 cases, and only 24.4% were diagnosed with malignant diseases. Among the MPs, the IgG-κ type was the most common type, followed by the IgG-λ, IgA-κ, IgA-λ, free λ light chain, IgM-κ, free κ light chain, double clone, and IgM-λ types. Differences in the MP of the IgG, IgA, IgM, and FLC types between the MM group and MGUS group were statistically different (P<0.01). The MP of the IgG, IgA, and FLC types showed clear specificity and sensitivity in discriminating MM from other monoclonal gammopathies in ROC curve analysis. Serum IgM had statistical significance in the differential diagnosis between WM and other MGs (P<0.01). However, there was no statistical significance in the differential diagnosis between MM and other MGs (P=0.140). The cutoff values of the MP of the IgG, IgA, and FLC types were >18.67g/L, >13.86g/L, and >10.15g/L, respectively, for the differential diagnosis of MM and other MGs. The cutoff value of the MP of IgM for the WM diagnosis was >37.75 g/L.
Conclusion: CE has good clinical application value in the diagnosis of monoclonal gammopathies, and MP can be used in the differential diagnosis of MM and other monoclonal gammopathies.
Keywords: MGRS; MGUS; ROC; capillary electrophoresis; cutoff value; monoclonal protein; multiple myeloma.
© 2021 by the Association of Clinical Scientists, Inc.