Diagnostic Use
Myeloma
This assay can be useful in the diagnosis and monitoring of light chain myeloma and non-secretory myeloma. This free light chain assay is useful only in cases where a serum paraprotein is absent or at too low a concentration to quantitate. When a quantifiable paraprotein is present, this should be monitored by protein electrophoresis.
In myeloma and MGUS (monoclonal gammopathy of undetermined significance) increased concentrations of free light chains (usually of a single type i.e. kappa or lambda) are frequently found in serum and urine, and the kappa / lambda ratio is abnormal.
In light chain myeloma, the typical finding is increased kappa or lambda free light chains in serum and urine, with an abnormal ratio, while a serum paraprotein may not be detectable on electrophoresis. Increased free light chains may also be found in non-secretory myeloma.
Amyloidosis
In amyloidosis, the finding of elevated free light chains in the serum suggests the type is AL amyloidosis (amyloidosis due to light chains) and the free light chain concentration can be used to monitor the response to therapy.
Biclonal gammopathies
Both light chain types may be increased, and the kappa / lambda ratio may be normal.
Polyclonal hypergammaglobulinaemia
There are increased concentrations of both kappa and lambda free light chains in serum and urine, but the kappa / lambda ratio is normal.
Test Method
Methodology: Turbidimetric assay
Platform: Optilite, Thermo Fisher Scientific