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HelpMayo Test ID FLCS Immunoglobulin Free Light Chains, Serum
Specimen Required
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Useful For
Monitoring serum from patients with monoclonal light chain diseases without a M-spike on protein electrophoresis
May be useful as a diagnostic test in patients in whom there is a suspicion of primary systemic amyloidosis, light chain deposition disease, or non-secretory myeloma
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| KFLCS | Kappa Free Light Chain, S | No | Yes |
| LFLCS | Lambda Free Light Chain, S | No | Yes |
| KLRS | Kappa/Lambda FLC Ratio | No | Yes |
Testing Algorithm
The following algorithms are available:
Special Instructions
Method Name
Turbidimetry
Reporting Name
Immunoglobulin Free Light Chains, SSpecimen Type
SerumSpecimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 28 days | |
| Frozen | 28 days | ||
| Ambient | 72 hours |
Reject Due To
| Gross hemolysis | OK |
| Gross lipemia | Reject |
| Gross icterus | OK |
Clinical Information
The monoclonal gammopathies are characterized by a clonal expansion of plasma cells that secrete a monoclonal immunoglobulin. The monoclonal immunoglobulin secreted by these cells serves as a marker of the clonal proliferation, and the quantitation of monoclonal protein can be used to monitor the disease course. The monoclonal gammopathies include multiple myeloma (MM), light chain MM (LCMM), Waldenstrom macroglobulinemia (WM), nonsecretory MM (NSMM), smoldering MM (SMM), monoclonal gammopathy of undetermined significance (MGUS), primary systemic amyloidosis (AL), and light chain deposition disease (LCDD). The monoclonal light chain diseases (LCMM, AL, LCDD, and NSMM) often do not have serum monoclonal proteins in high enough concentration to be detected and quantitated by serum protein electrophoresis.
An elevated ratio of kappa to lambda free light chains (FLC K/L) indicates a monoclonal kappa FLC, and an abnormally low FLC K/L indicates a monoclonal lambda FLC. The kappa and lambda FLC may both be elevated in the sera of patients with polyclonal hypergammaglobulinemia, but the FLC K/L is normal. If a patient has an abnormal serum FLC K/L ratio but has no serum monoclonal protein detected by immunofixation, a urine monoclonal protein study (eg, immunofixation) should be performed and the serum immunofixation should be repeated.
The FLC K/L ratio may be useful as a diagnostic test for patients in whom immunofixation for serum monoclonal light chains is negative and in whom there is a suspicion of primary systemic amyloidosis, light chain deposition disease, or non-secretory myeloma.
The quantitation of kappa or lambda immunoglobulin free light chains may be used to monitor disease activity in patients with monoclonal light chain diseases without a serum M-spike.
The following algorithms are available:
Reference Values
KAPPA-FREE LIGHT CHAIN
0.33-1.94 mg/dL
LAMBDA-FREE LIGHT CHAIN
0.57-2.63 mg/dL
KAPPA/LAMBDA FLC RATIO
0.26-1.65
Interpretation
The specificity of this assay for detection of monoclonal light chains relies on the ratio of free kappa and lambda (K/L) light chains. Once an abnormal free light chain (FLC) K/L ratio has been demonstrated and a diagnosis has been made, the quantitation of the monoclonal light chain is useful for monitoring disease activity.
Changes in FLC quantitation reflect changes in the size of the monoclonal plasma cell population. Our experience to date is limited, but changes of more than 25% or trending of multiple specimens are needed to conclude biological significance.
Cautions
Elevated kappa and lambda (K/L) free light chain (FLC) may occur due to polyclonal hypergammaglobulinemia or impaired renal clearance. A specific increase in FLC (eg, FLC K:L ratio) must be demonstrated for diagnostic purposes.
This assay has not been established for use with the pediatric population.Â
Moderate-to-marked lipemia may interfere with the ability to perform testing.
Clinical Reference
1. Kaleta E, Kyle R, Clark R, Katzmann J: Analysis of patients with gamma-heavy chain disease by the heavy/light chain and free light chain assays. Clin Chem Lab Med. 2014 May;52(5):665-669. doi: 10.1515/cclm-2013-0714
2. Palladini G, Russo P, Bosoni T, et al: Identification of amyloidogenic light chains requires the combination of serum-free light chain assay with immunofixation of serum and urine. Clin Chem. 2009 Mar;55(3):499-504. doi: 10.1373/clinchem.2008.117143
3. Dispenzieri A, Kyle R, Merlini G, et al: International Myeloma Working Group guidelines for serum-free light chain analysis in multiple myeloma and related disorders. Leukemia. 2009 Feb;23(2):215-224. doi: 10.1038/leu.2008.307
4. Drayson M, Tang LX, Drew R, Mead GP, Carr-Smith H, Bradwell AR: Serum free light chain measurements for identifying and monitoring patients with nonsecretory multiple myeloma. Blood. 2001 May 1;97(9):2900-2902
Method Description
The determination of the soluble antigen concentration by turbidimetric methods involves the reaction with specific antiserum to form insoluble complexes. When light is passed through the suspension formed a portion of the light is transmitted and focused onto a photodiode by an optical lens system. The amount of transmitted light is indirectly proportional to the specific protein concentration in the test sample. Concentrations are automatically calculated by reference to a calibrations curve stored within the instrument.(Package inserts: Optilite Freelite Kappa Free Kit. The Binding Site Group, Ltd; 08/2018; Optilite Freelite Lambda Free Kit. The Binding Site Group, Ltd; 08/2018)
Specimen Retention Time
14 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
83521 x 2
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| FLCS | Immunoglobulin Free Light Chains, S | 104533-5 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| LFLCS | Lambda Free Light Chain, S | 33944-0 |
| KLRS | Kappa/Lambda FLC Ratio | 104546-7 |
| KFLCS | Kappa Free Light Chain, S | 104544-2 |
Day(s) Performed
Monday through Friday