title: Linearity and detection limit in the measurement of serum M-protein with the capillary zone electrophoresis system Capillarys.
abstract: We studied the linearity and detection limits of the capillary zone electrophoresis system Capillarys in the measurement of serum monoclonal protein. Three monoclonal proteins with different isotypes and electrophoretic migrations were diluted with a hypo-gamma-globulinemic polyclonal serum pool. Mathematical linearity was observed for all monoclonal protein isotypes in the ranges studied without removing the polyclonal gamma-globulin background. Theoretical concentrations of 0.43, 0.89 and 0.33 g/L for monoclonal proteins immunoglobulin (Ig)G, IgA and IgM, respectively, gave a discernible spike by Capillarys, although they were measured as 0.76, 1.09 and 0.76g/L, respectively. We observed overestimation of monoclonal protein inversely correlated to concentrations below 15 g/L. All these limitations have to be taken into account when monitoring monoclonal proteins, because the loss of linearity and the protein background may hide an increase in concentration at low levels.
authors.affiliation: Department of Clinical Pathology, Hospital Universitario de Getafe, Madrid, Spain. enbergon@terra.es
authors.forename: Enrique
authors.initials: E
authors.lastname: Bergón
authors.forename: Isabel
authors.initials: I
authors.lastname: Miranda
authors.forename: Elena
authors.initials: E
authors.lastname: Miravalles
mesh_terms: D001797:Blood Protein Electrophoresis / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D019075:Electrophoresis, Capillary / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D007162:Immunoproteins / Q000032:analysis*; D010265:Paraproteinemias / Q000097:blood / Q000276:immunology
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007162:Immunoproteins