Raised light chains

Last updated Nov. 1, 2025, 10:32 p.m. by ivo

Tags: Amyloidosis , MGUS , Myeloma , Raised light chains

Serum free light chains are used to assess for clonally-restricted plasma cell populations. As such, they are only diagnostically useful and reflect possible pathological plasma cell conditions when there are elevated kappa or lambda serum free light chains AND the ratio of kappa to lambda free light chains is abnormal.

Serum electrophoresis testing is required in addition to serum free light chain testing to adequately exclude clonal plasma cell disorders. Absolute levels of free light chains may be elevated in inflammatory states (reflecting polyclonal hypergammaglobulinaemia) and renal impairment (reflecting reduced renal clearance of free light chains) and are of no consequence in the setting of a normal kappa:lambda ratio. Patients with an abnormal serum free light chain ratio require investigation to assess if they have MGUS, myeloma or amyloidosis.

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When To Refer

• Raised either Kappa or Lambda or both
AND
• Kappa / Lambda ratio is abnormal (high >2, low < 0.1)*
* ^{actual values may differ between labs}