Combined light chain immunofixation to detect monoclonal gammopathy: a comparison to standard electrophoresis in serum and urine

Background: The purpose of this study was to evaluate a combined. and. light chain immunofixation (CLIF) as a screening tool to detect monoclonal immunoglobulins in serum and urine. A secondary aim was to investigate the impact on workflow and reagent utilisation of a systematic implementation of CLIF in addition to routine protein electrophoresis (PE) on all samples. Methods: Light chain antisera (kappa and lambda) were mixed in a 1: 1 ratio and loaded in the same sequence as the PE to create a superimposable image. Results: The CLIF procedure agreed significantly better with standard immunofixation procedures in the serum and urine. In 33 (22%) new patients and in 114 (15%) follow-up patients CLIF detected a band missed by PE in serum. In 34 (4.5%) of previously categorised cases the monoclonal band was below the detection limit of CLIF in serum, but still detectable by conventional immunofixation electrophoresis. In one case (0.7%) a band in a urine specimen was missed by CLIF compared to 70 (49%) missed by PE. After the systematic introduction of CLIF turn-around-times (TATs) and utilisation of laboratory consumables decreased significantly (p<0.001). Conclusions: A systematic implementation of CLIF led to the detection of monoclonal bands missed by PE with an improvement in TATs and a decrease in cost.