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Free Light Chains

Immunoglobulin Free Light Chains, Serum Free Light Chains, SFLC, FLC

Test Codes

EPIC: LAB5856, Beaker: FRLC, Antrim #19314

Department

Special Chemistry

Specimen Collection Criteria

Collect: One Gold-top SST tube. (Minimum Whole Blood: 2.0 mL)

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged collection tube within eight hours of collection. (Minimum Serum: 0.5 mL)

Preparation for Courier Transport

Transport: Centrifuged collection tube, refrigerated (2-8 °C or 36-46 °F). (Minimum Serum: 0.5 mL)

Rejection Criteria

• Plasma specimens. 
• Severely hemolyzed, lipemic or icteric specimens.   
• Specimens that have gross bacterial contamination.

In-Lab Processing

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Room temperature is acceptable for a maximum of eight hours. (Minimum Serum: 0.5 mL)

Storage

Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers^® with Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 8 hours
Refrigerated (2-8°C or 36-46°F): 21 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers^® without Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 8 hours
Refrigerated (2-8°C or 36-46°F): 21 days
Frozen (-20°C/-4°F or below): 21 days

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Royal Oak Special Testing Laboratory

Performed

Monday, Wednesday, Friday.
Results available the same day as testing performed.

Reference Range

Free Kappa: 0.33-1.94 mg/dL.
Free Lambda: 0.57-2.63 mg/dL.
Kappa/Lambda Ratio: 0.26-1.65

Test Methodology

Immunoturbidimetry (Binding Site).

Interpretation

• Elevated Free Kappa/Free Lambda ratio is very suggestive of a monoclonal free kappa light chain.
• Decreased Free Kappa/Free Lambda ratio is very suggestive of a monoclonal free lambda light chain.
• Free kappa and free lambda light chains may both be elevated in patients with polyclonal hypergammaglobulinemia.
• Note: Test results should be used in conjunction with clinical findings.

Clinical Utility

Patients with monoclonal gammopathies, in particular those with light chain multiple myeloma, non-secretory myeloma, amyloidosis, and light chain deposition disease may not be detected by Serum Protein Electrophoresis alone and in some cases not even by Serum Immunofixation. Recent studies have shown that an assay for free kappa and free lambda light chains is more sensitive for diagnosis and monitoring of these conditions. Calculation of the ratio of free kappa to free lambda light chains is particularly helpful for diagnosis in the following cases:

• Diagnostic test in patients with a negative immunofixation, but for whom there is a high degree of suspicion for myeloma, amyloidosis, or light chain deposition disease.
• Monitoring disease activity in patients with the above conditions.

Use of Protein Electrophoresis, Immunofixation, or the Serum Monoclonal Gammopathy Evaluation are still regarded as first line tests in screening for monoclonal gammopathies. Free light chain testing is not currently appropriate for patients who have a monoclonal protein that can be quantitated by protein electrophoresis.

Reference

1. Roshini S. et al. Anew marker for the diagnostic evaluation of primary systemic amyloidosis. Amer J Clin Path 2003;119:274-78.
2. Katzmann JA et al. Serum reference intervals and diagnostic ranges for free kappa and free lambda immunoglobulin light chains: Relative sensitivity for detection of monoclonal light chains. Clin Chem 2002;48: 1437-44.

CPT Codes

83520 x 2

Contacts

Last Updated

1/8/2024