Serum Free Light Chains

Free Light Chains SFLC FLC Kappa and Lambda Free Light Chains Quantitative Serum Free Light Chains with Ratio

Why test for Serum Free Light Chains

Serum free light chain (SFLC) testing is ordered to help detect, diagnose, and monitor plasma cell disorders (dyscrasias), including multiple myeloma, primary amyloidosis, and related diseases or to monitor the effectiveness of treatment.

Light chains are proteins produced by plasma cells. Within a plasma cell, two light chains and two heavy chains combine to form an immunoglobulin.

With a group of conditions called plasma cell disorders or monoclonal gammopathies, a plasma cell becomes neoplastic, dividing more than it should, and produces large amounts of an abnormal monoclonal immunoglobulin (M-protein). This protein may be an intact immunoglobulin or only one of its components – a kappa or lambda light chain, or rarely, a heavy chain.

Plasma cell disorders are routinely diagnosed using serum and urine protein electrophoresis tests (SPEP/UPEP), followed by immunofixation electrophoresis (IFE) tests to determine which immunoglobulin is present in excess. Blood tests may also be ordered to measure levels of intact immunoglobulins (e.g., IgG, IgM, IgA).

Serum free light chain testing provides complementary information. It can detect the excessive free light chains that may be produced by neoplastic plasma cells and changes in the ratio of kappa and lambda production, which indicate an excess of these clonal plasma cells.

Initially, serum free light chain testing is ordered along with a serum protein electrophoresis test to detect abnormal monoclonal protein (M-protein) production and to calculate a kappa/lambda free light chain ratio. If the protein electrophoresis test is abnormal, then an immunofixation electrophoresis test is performed to determine which immunoglobulin is present in excess. If a plasma cell disorder is detected, then the free light chain test may be ordered periodically to monitor the condition or to evaluate the effectiveness of treatment. This test is particularly useful for diagnosing and monitoring select patients who have a less common oligosecretory myeloma, non-secretory myeloma, or light chain-only multiple myeloma.

SOURCE: https://labtestsonline.org/tests/serum-free-light-chains