Five unusual serum protein presentations found by capillary electrophoresis in the clinical laboratory.

Capillary electrophoresis (CE) has been used in our teaching hospital clinical laboratory to assay approximately 13 000 specimens for serum protein electrophoresis (SPE) in 4 1/2 years. During that period we have found several unusual samples, five of which are discussed here. These samples are from separate patients with IgD myeloma, IgG heavy chain disease, a triple IgG(Kappa) monoclonal band, a rapidly changing abnormal/monoclonal band and a mixed type-11 cryoglobulinaemia. Albumin has been used to calibrate the 50-microm fused silica capillary, the quantity of the monoclonal bands being calculated by the software of either the Applied Biosystems 270A-HT or BioFocus instrument. We have found CE for the initial SPE to be a robust, labour-saving, cost effective technique, which is able to determine less than 1 g/l of monoclonal protein. However, because of the expense and time required for immunosubtraction, we prefer isoelectric focusing (IEF) for typing of paraproteins. The only samples which need care in handling are serum containing large amounts of cryoglobulin protein.