From the Guidelines
Protein electrophoresis is a crucial laboratory test for identifying and monitoring abnormal proteins in blood, urine, or other body fluids, and it should be used in conjunction with other diagnostic tests to assess disease progression and treatment effectiveness in conditions like multiple myeloma, as recommended by the most recent guidelines 1.
Key Points
- Protein electrophoresis separates proteins based on their electrical charge and size, providing valuable information about protein-related disorders and immune system function.
- The test is used to identify abnormal proteins, determine the quantity of different protein types, and detect conditions such as multiple myeloma, amyloidosis, kidney disease, and certain immune disorders.
- Abnormal patterns, such as monoclonal spikes in the gamma region, can indicate specific diseases like multiple myeloma, while decreased albumin might suggest liver disease or malnutrition.
- Results are typically interpreted alongside other clinical findings and may require follow-up tests like immunofixation electrophoresis for more detailed protein identification.
Diagnostic Approach
- Urine analysis, including 24-hour urine for total protein, urine protein electrophoresis (UPEP), and urine immunofixation electrophoresis (UIFE), is part of the initial diagnostic workup for multiple myeloma.
- Serum analysis, including quantitative immunoglobulin levels, serum protein electrophoresis, and serum immunofixation electrophoresis, provides more specific information about the type of M-protein present.
- Assessing changes in levels of various proteins, particularly the M-protein, helps track disease progression and response to treatment, as noted in the guidelines 1 and 1.
Clinical Implications
- Protein electrophoresis is a relatively simple, non-invasive test that provides valuable diagnostic information about protein-related disorders and immune system function.
- The test is particularly valuable for monitoring disease progression and treatment effectiveness in conditions with abnormal protein production, as highlighted in the study 1.
- The use of serum free light chain (FLC) assay along with serum protein electrophoresis and serum immunofixation electrophoresis yields high sensitivity while screening for multiple myeloma and related plasma cell disorders, as recommended in the guidelines 1.
From the Research
Protein Electrophoresis Techniques
- Serum protein electrophoresis (SPE) and immunofixation electrophoresis (IFE) are standard tools for multiple myeloma (MM) routine diagnostics 2, 3, 4, 5.
- SPE separates proteins based on their physical properties, and the subsets of these proteins are used in interpreting the results 4.
- IFE detection technique can be used for screening M protein in patients with atypical MM, and can increase the diagnosis accuracy in patients with atypical MM 3.
Detection and Quantification of M-Protein
- M-protein is a biomarker for MM that can be quantified with SPE and characterized with IFE 2.
- The detection rate of M protein by IFE detection was better than that of SPE 3.
- SPE-MS assay offers the possibility to detect M-protein with higher sensitivity than SPE/IFE, which could lead to better analysis of minimal residual disease in clinical laboratories 2.
- Using SIL peptides, the limit of detection of the M-protein is approximately 100-fold better than with routine SPE/IFE 2.
Clinical Applications
- SPEP is an easy to perform laboratory test which can be used for detection and quantification of monoclonal gammopathy and should be recommended as preliminary test for suspected cases of multiple myeloma 5.
- Serum free light chain measurements can provide greater sensitivity than urine electrophoresis for monitoring multiple myeloma 6.
- Response criteria for multiple myeloma are based upon changes in monoclonal protein levels quantified using serum and/or urine protein electrophoresis 6.
Comparison of Techniques
- There was substantial agreement between predicate (serum/urine protein electrophoresis) and test (serum protein electrophoresis and serum free light chain) methods for response assessment 6.
- Urine immunofixation became negative in 47% light chain and 43% intact immunoglobulin patients after 2 cycles of therapy, while the serum free light chain ratio normalized in only 11% and 27% patients, respectively 6.