QA Scheme
Quality assurance for free light chain analysis
It is essential that all laboratories participate in external quality control schemes when performing monoclonal protein analysis.
The Binding Site QA Scheme QA 003
Because there are currently no international or national schemes for quantification of serum free light chains, Binding Site has developed its own QA programme targeted specifically at serum free light chain analysis.
Freelite serum free light chain analysis
Around 100 laboratories worldwide participate in this scheme currently, methodologies include Serum Protein Electrophoresis (SPE) and Immunofixation Electrophoresis (IFE).
Six sets of samples are issued per year and each contains unmatched serum and urine samples. The results are returned to each laboratory include photocopies of electrophoresis gels, comparisons with other laboratories' results and an 'expert opinion' regarding the sample and results.
Example results are shown for the serum sample in QA003 distribution number 78.
SPE Gel: Tracks 1-4 normal sera, Tracks 5-7 serum sample, (Tracks 8-10 urine sample in same distribution)
IFE Gel
Of the laboratories who returned SPE results 74% detected paraprotein present. 88% detected IgG kappa and or free kappa chains by IFE. All laboratories using immunoassays to measure serum free light chains reported the elevated kappa chains and the elevated FLC ratio.
Expert Opinion:
The serum sample was from a patient with IgG kappa Myeloma. A monoclonal band was visible on SPE and both an IgG band and a free kappa band were visible on IFE. The IgG band was only weakly detected by anti IgG and kappa antisera. The sample showed severe immunoglobulin suppression but elevated β2.
Results returned from these QA Scheme samples have highlighted on several occasions, the improvements that could be made if laboratories were using immunoassays of free light chain in serum instead of qualitative methods, especially urine electrophoresis.
