Free light chains
Serum Free Light Chains
Gold or Red tube
Paediatric Gold or Red tube
Free kappa light chains: 3.3 – 19.4 mg/L, Free lambda light chains: 5.7 – 26.3 mg/L, Kappa/Lambda Ratio 0.26 – 1.65
In renal failure both kappa and lambda free light chains are increased and the ratio may be increased to 0.36 - 3.1, the upper limit may be even up to 4.9 in some patients with end stage renal failure.
In patients with a polyclonal increase in immunoglobulin levels, kappa and lambda free light chains may also increase and the ratio may increase up to 3.1.
Free kappa light chains <35%, Free lambda light chains <25%, Kappa:Lambda ratio <45%
The test measures the total amount of immunoglobulin light chain in the serum that is unbound ("free") to immunoglobulin heavy chains. An imbalance of kappa v lambda isotypes is suggestive of monoclonal plasma cell dyscrasia.
The test can be used instead of urinary Bence Jones Protein in screening and diagnosis.
Choosing Clinical Laboratory Tests Wisely Guidelines:
The test measures the total amount of immunoglobulin light chain in the serum that is unbound (“free”) to immunoglobulin heavy chains. An imbalance of kappa v lambda isotypes is suggestive of monoclonal plasma cell dyscrasia. The test can be used instead of urinary Bence Jones Protein.
The International Myeloma Working Group guidelines suggest that Serum Free Light Chains are used for prognostic purposes in patients with monoclonal gammopathy of unknown significance (MGUS) and also smouldering multiple myeloma, active multiple myeloma and amyloidosis.
The test is indicated if the patient:
It should only be performed with a maximal frequency of once every 4 weeks. It is anticipated testing is needed no more frequently than every 3 months unless on active chemotherapy.
Our multiple myeloma guidelines suggest the acronym CRAB is a helpful guide to investigate for myeloma.
Test if any of the following are unexplained:
- Calcium elevation
- Renal impairment (acute or chronic)
- Anaemia (< 100g/L or > 20g/L below normal)
- Bone (lytic lesion, crush fractures, osteopenia)