Blood serum free light chain concentration vs. immunofixation results in patients with monoclonal gammopathy

Abstract

Monoclonal gammapathies are a group of diseases characterized by proliferation of plasma clone cells that produce a certain type of homogenic immunoglobulin containing heavy chains of a, g, m, d, e class aside a type of light k or l chains. Standard methods applied to detect and identify the type of monoclonal protein in patients suspected of monoclonal gammapathy include serum electrophoresis and immunofixation. Quantitative analysis of free light chains (FLCs) by nephelometry has become more popular recently. The purpose of the study was to compare the results and assess the compatibility of free light chains measurements obtained by nephelometry and standard immunofixation. In addition to that, we tried to evaluate the usefulness of serum FLC analysis in the detection of monoclonal protein. The investigation was carried out in the group of 92 patients with suspected monoclonal gammapathy. In most cases concentrations of FLCs are increased depending on the type of light chain determined by immunofixation, however normal values of FLCs and normal kappa/lambda ratio do not exclude the presence of monoclonal protein. The analysis of FLC is most useful to identify patients suspected of light chain disease. Immunofixation is more sensitive method to detect gammapathies with complete monoclonal protein in comparison to quantitative FLC analysis.