Use of Immunoglobulin Heavy-Chain and Light-Chain Measurements in a Multicenter Trial to Investigate Monoclonal Components: I. Detection

We assessed the combined use of serum protein electro-phoresis (SPE) and nephelometric measurement of im-munoglobulin heavy- and light-chain components for de-tecting serum monoclonal immunoglobulins (monoclonal components, MC) in 4788 unselected samples from 4173 patients. MC were detected in 514 samples from 390 patients. In 356 these were detected by SPE; the other 34 had a normal SPE pattern but an abnormal kappa:Iambda light-chain ratio (KLR). Only 208 of the 356 (58%) sam-ples with bands by SPE had abnormal KLRs. Samples with MC concentrations>5 g/L had a higher proportion of abnormal KLRs (75%) than those with concentrations <5 gIL (42%). The KLR was abnormal in 13 % of samples in which no MC were visible by SPE or immunofixation electrophoresis (IFE). Compared with quantitative mea