Laboratory tools for oligo-secretory myeloma diagnosis: capillary electrophoresis versus free light chain assay

To investigate how capillary electrophoresis (CE) works in oligo-secretory myeloma (OSM), we report a case here of OSM using multiple diagnostic methods including gel electrophoresis (GE), CE, and free light chain assay (sFLC). Also, we provide a brief review of laboratory methods to compare their diagnostic utilities in OSM.A 72 year-old Korean male suffering from low back pain during the past 6 months was transferred to the department of neurosurgery in order to evaluate abnormal findings in an imaging study, suggesting plasma cell myeloma (PCM) with multiple bone metastasis. CE showed no suspicious M-component; however, it showed increased Kappa components and skewing Kappa/Lambda ratio (K/L). Bone marrow examination revealed plasma cells observed up to 70%, which were compatible with sFLC results.Based on these results, the diagnosis turned out to be OSM with multiple bone metastases. Thereafter, the patient started the first cycle of chemotherapy accompanied by palliative radiation therapy.In our case, sFLC showed abnormal Kappa and K/L results from both serum and urine specimen. Therefore, it seems to be more sensitive and appropriate than both GE and CE to diagnose OSM.