Monitoring Monoclonal Gammopathies

Relationship of Serum Agarose Electrophoresis M-spike and Ig Quantitation

November 2009

We have compared electrophoretic and nephelometric quantitation of monoclonal proteins. And in this slide, you can see that the relationships are dependent on the heavy chain isotype. IgA monoclonal proteins yield a good relationship with a slope of 1. That is, the IgA M-spike correlates well with IgA by nephelometry. IgM also yields a linear relationship, but nephelometric results are 80% higher than IgM M-spikes. And lastly, IgG monoclonal proteins do not have a linear relationship. We believe that the nonlinearity is due to gel saturation when IgG M-spikes are >3 g/dL.

This has led us to conclude that although serum protein electrophoresis M-spikes are better for monitoring most monoclonal proteins, nephelometric quantitation is probably better for large M-spikes. In addition, as has been known for a long time, because quantitation is different by the 2 methods, clinicians should not go back and forth when monitoring patients.

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Jump to section:

• Introduction
• Slide Images
• International Myeloma Working Group: Disease Monitoring
• Serum Protein Electrophoresis and Immunofixation Electrophoresis
• Serum and Urine Protein Electrophoresis and Immunofixation Electrophoresis
• Methods for Monitoring Monoclonal Gammopathies: 2005 IMWG
• Methods for Monitoring Monoclonal Gammopathies
• Small IgG kappa M-spike
• Large IgG kappa M-spike
• Relationship of Serum Agarose Electrophoresis M-spike and Ig Quantitation¹
• Disease Monitoring
• Monoclonal Gammopathies: Primary Systemic Amyloidosis
• Free Light Chain: Antibody Specificity
• FLC κ/λ Ratio: Disease Sensitivity²
• Methods for Monitoring Monoclonal Gammopathies
• International Myeloma Working Group: 2009 Guidelines for Disease Monitoring³
• Response Criteria for FLC^4,5
• Receiver Operator Curve (ROC): % FLC Reduction vs. Overall Hematologic Response⁶
• International Myeloma Working Group: 2009 Guidelines for Disease Monitoring
• References
• Questions?