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Summary:

  • Serum protein electrophoresis detects the majority of monoclonal intact immunoglobulins, but is considerably less sensitive than sFLC analysis for identifying monoclonal FLCs.
  • Capillary zone electrophoresis offers a more automated alternative to serum protein electrophoresis, and is increasingly being used by laboratories with a large workload.
  • Once identified, monoclonal proteins are typed using immunofixation electrophoresis or immunosubtraction.
  • Monoclonal intact immunoglobulins that co-migrate with other serum protein peaks on serum electrophoresis may be more accurately quantifed using total immunoglobulin or Hevylite®immunoassays.
  • There are wide variations in laboratory protocols for urine protein electrophoresis.

The detection of monoclonal intact immunoglobulins and/or free light chains (FLCs) forms part of the diagnostic criteria for many plasma cell disorders, although the requirement for the presence of a monoclonal protein is no longer mandatory for the diagnosis of multiple myeloma (MM) (Section 25.2). The same tests, which are used diagnostically, are frequently employed for monitoring disease and defining the response to treatment (Chapter 25) [113][114][115][116][117][118]. This chapter provides an overview of the methodology and analytical sensitivity of routine laboratory methods used to identify and quantify monoclonal immunoglobulins.