Diagnostic Use
The test works by separating serum proteins through electrophoresis and then using antibodies to fix and identify specific immunoglobulin types (routinely against IgG, IgA, IgM heavy chains, kappa and lambda light chains; rarely IgD and IgE heavy chains are also tested). Unlike standard serum protein electrophoresis, immunofixation can detect smaller quantities of monoclonal proteins, making it especially useful for early diagnosis of e,g, multiple myeloma and for confirming ambiguous serum protein gel electrophoresis results. It is also used to monitor disease progression of different clonal gammopathies and treatment response, as the presence or absence of monoclonal bands can indicate active disease or remission.
At CMH biochemistry laboratory, serum Immunofixation test is performed when :
- Specifically requested on the laboratory request form
- A new abnormal band is detected at the serum protein gel electrophoresis – for characterisation
- Even if there is no abnormal band at serum protein gel electrophoresis, serum immunofixation might still be performed if there has been a history of clonal gammopathies (generally not less than 6 months from the last immunofixation), abnormal serum free light chain ratio, or history of peripheral neuropathy – as it is more sensitive than serum protein gel electrophoresis or capillary electrophoresis tests.
Paraprotein band quantitation is performed separately by Capillary protein electrophoresis.
Reference Intervals
It is reported as a qualitative description.