Serum Free Light Chains (SFLC)

Immunology

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Description

Immunoglobulins are comprised of two heavy ( either G, A, M, D or E ) and two light chains ( kappa or lambda ). In healthy individuals there is a small excess of free light chain ( FLC ) production with monomers of kappa molecules and dimers of lambda molecules. Serum concentrations of FLCs are dependent on the balance between production and renal clearance [1]. When there is increased polyclonal immunoglobulin production and/or renal impairment, both kappa and lambda FLC concentrations can increase 10- to 20-fold. However, the relative concentration of kappa to lambda, i.e. the kappa/lambda ratio, remains unchanged [2,4]. In contrast, tumours produce a monoclonal excess of only one of the light chains, often with bone marrow suppression of the other light chain, so that kappa/lambda ratios become highly abnormal. Serum FLC measurement can therefore be used to provide a numerical indicator of clonality [1,4]. Guidelines for the management and monitoring of myeloma suggest that serum FLCs may be useful in monitoring free light chain only myeloma [3]. Abnormal FLC levels and ratio can be found in multiple myeloma, Bence Jones proteinuria, non-secretory myelomas, free light chain disease and primary amyloidosis [1].

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Indications

Over production of the free light chains can be seen in conditions such as monoclonal gammopathy, light chain diseases, non secretory myelomas, and amyloidosis.

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Sample Type

2mL Serum ( Gel 5mL Yellow tube ). Requests from outside Sheffield: Transport at ambient temperature via Royal Mail or Courier.

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Reference Range

Analyte | Normal range
Free kappa | 3.3 - 19.4 mg/L.
Free Lambda | 5.71 - 26.3 mg/L.
Kappa:Lambda ratio | 0.26 - 1.65.

Reference ranges established by manufacturer.

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Turnaround Time

Within 5 days

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Testing Frequency

Weekly

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References

Bradwell AR. Serum free light chain analysis. 5th Edition. 2009. [Ref 1]Hutchison CA, et al. Serum free light chain measurement aids the diagnosis of myeloma in patients with severe renal failure. BMC Neph. 2008. 9( 11 ):1-8. [Ref 2]Smith A, et al. Guidelines on the diagnosis and management of multiple myeloma 2005. Br J Haem. 2006. 132:410-451. [Ref 3]Bradwell AR. Serum free light chain measurements move to centre stage. Clin Chem. 2005. 51:805-807. [Ref 4]Rajkumar S, et al. International myeloma working group updated criteria for the diagnosis of multiple myeloma. 2014. Lancet Oncology, 15:e538-548.NICE Guideline ( NG35 ) Myeloma: diagnosis and management. February 2016 ( updated October 2018 ).

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See Also

Immunoglobulins; Bence Jones Protein/ Urine Light Chains

Please note: the above information is subject to change and we endeavour to keep this website up to date wherever necessary.