Comparative evaluation of free light chain assays in AL amyloidosis: Performance of Sebia versus Freelite and N-Latex

•Analytical performance of the Sebia free light chain ELISA was evaluated in systemic AL amyloidosis and compared with Freelite and N-Latex assays.•Sebia reported lower involved and difference FLC concentrations than comparator assays, particularly in λ-type disease.•Sebia showed reduced detection rates for abnormal κ/λ ratios compared with N-Latex and Freelite, most pronounced in λ-type disease.•Combining Sebia with serum and urine immunofixation improved detection of amyloidogenic clones.•These findings demonstrate that FLC assays are not interchangeable and require assay-specific interpretation.