A 79-year old man presented at the emergency ward of our hospital with symptoms characteristic for multiple myeloma. Although serum capillary zone electrophoresis appeared normal, kappa free light chains were found in serum and in urine by immunofixation electrophoresis. The kappa free light chain fraction detected in the serum, albeit appeared as a polyclonal-like smear with an aberrant localisation in the alpha-2- and beta-regions. Subsequent high resolution gel electrophoresis of the serum suggested the presence of a monoclonal fraction in the alpha-2- and beta-regions, but quantification of the band by densitometry was still not possible. Quantification of free light chains in the patient’s serum by immunonephelometry indicated the presence of an excessive amount of kappa free light chains. However, overestimation of the amount of kappa free light chains by the immunonephelometric method was suspected because of discrepancy with the intensity of the fractions on serum and urine immunofixation electrophoresis.

(BELG J HEMATOL 2016;7(5):194–8)