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PTD - 211

Test Directory - Free Light Chains




Clinical Indications

Investigation and monitoring of B cell dyscrasias, especially light chain only myeloma, MGUS, amyloid.
Serum Free Light Chains have a role in the diagnosis of primary systemic amyloidosis (AL) with up to 98% of patients demonstrating abnormal levels.
Because of their shorter half-life, FLC may show a quicker response to treatment then intact immunoglobulin.
Further investigation of an abnormal band in serum.

Request Form

Combined Pathology Blood form (Yellow/Black)


Analysed if specific criteria met

Specific Criteria

Request by Consultant Haematologist or Renal Physician. Not requested within previous 4 weeks (unless specifically agreed).

Samples referred to Basildon Hospital for Free Light Chain analysis should be packaged in line with our transportation policy and will be assumed to have met the specific criteria of the referring laboratory.

Patient Preparation


None required

Turnaround Time

One week.




5 ml


Yellow top (SST) tube

Causes for Rejection

Unlabelled sample; assay within previous 4 weeks
Not requested or authorised by Consultant Haematologist/Nephrologist.

Reference Range

Serum kappa FLC     3.3     19.4  mg/L
Serum lambda FLC   5.7     26.3  mg/L
Kappa/lambda ratio   0.26   1.65


Increased levels may be seen with raised polyclonal immunoglobulin, and in renal impairment. Abnormal ratio indicates B cell dyscrasia

Antigen excess causes all immunoassays to underestimate very high levels of antigen. Free-lite assays are manufactured to minimise antigen excess, but it is not possible to completely eradicate it. Free-lite results should be interpreted in conjunction with other laboratory tests and clinical history.

From 14.04.2014 the serum FLC assay has been transferred from Roche Cobas to SPA-Plus analyser. Patient comparison data showed significant differences between methods at higher values. Therefore, in previously monitored patients, with serum Kappa FLC of >50 mg/L or a Lambda FLC of >70 mg/L as analysed with the new SPA-Plus method samples were also analysed by Roche Cobas method to provide dual reporting for a six month period.

Lab. Handling

Processing: Aliquot (MPA) and store at 4C in separating fridge (CB39), rack 120, until analysis.

Version 1.1 / October 2014                                                                                                      Approved by: Consultant Biochemist