Immunoglobulin G paraprotein cross-reactivity with immunoglobulin M measurement

Abstract

We report a case of IgG paraprotein cross-reactivity with IgM measurement in a patient with IgGkappa multiple myeloma and associated IgA and IgM immune paresis. IgM measurements using a Beckman-Coulter Synchron LX IgM reagent initially gave unmeasurably low IgM concentrations (<0.3 g/L) but IgM quantitation using later batches of reagent gave IgM concentrations of 13-42 g/L. Immunofixation confirmed the continued presence of the IgGkappa paraprotein band with suppression of IgA and IgM and analysis on the Behring BN2 and Beckman-Coulter Immage instruments showed IgM concentrations of <0.2 g/L. Immunofixation using the Synchron LX IgM reagent as antiserum confirmed binding of the Synchron LX IgM antiserum to the IgGkappa paraprotein. This case highlights the importance of checking all unexpected immunoglobulin measurements with previous results and immunofixation findings to avoid mistakes.

Commutability evaluation of candidate reference materials and ERM‐DA470k/IFCC for immunoglobulin M using two international approaches

“…CLSI approach based on principle of statistics; however, IFCC approach was performed according to laboratory measurement, such as bias and measurement uncertainty, et al The median concentration of PHS mainly came from healthy patients, while some high concentration and low concentration of PHS came from patients with multiple myeloma. Robert reported IgG paraprotein cross‐reactivity with IgM measurement in a patient with IgG‐k multiple myeloma 20 . There is mutual interference in some assay combinations detection needs to be further verified.…”

“…Robert reported IgG paraprotein cross‐reactivity with IgM measurement in a patient with IgG‐k multiple myeloma. 20 There is mutual interference in some assay combinations detection needs to be further verified.…”