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Laboratory Medicine

Test Directory / Serum Free Light Chain

Serum Free Light Chain

Brown clotted serum, gel barrier

TestSerum Free Light Chain
Common AbbreviationsFLC
Tube typeBrown clotted serum, gel barrier
Clinical IndicationFree light chains are measured in the serum of patients to diagnose and monitor primarily multiple myeloma, but also in the monitoring of lymphocytic neoplasms, Waldenstroms macroglobulinaemia, AL amyloidosis, light chain deposition disease and connective tissue disease.
Specimen TypeBlood
Sample typeSerum
Minimum Volume2mL
Special PrecautionsOnly available if directed by a haematologist
Stability21 days stored at 2-8°C or for prolonged storage -20°C. Repeated freeze/thaw samples should be avoided.
Turnaround Time10 days
LaboratoryThis assay is performed in the York Laboratory. For trial patients only contact Referral Laboratory: Clinical Immunology Service The Medical School Edgbaston Birmingham B15 2TT 0121 414 4069
Reference IntervalReference range may vary with age, sex, sample type, diet and geographical location. Free Kappa; 3.30 to 19.40 mg/L Free Lambda; 5.71 to 26.30 mg/L Kappa/Lambda Ratio; 0.26 to 1.65 - provided by Binding Site and were obtained in US using the Binding Site Freelite assay on BN II. Kappa/Lambda Ratio in dialysis patients; 0.37 to 3.10 – as a result of study performed in Birmingham. The results of this assay must be assessed in conjunction with the patient’s medical history, clinical examinations, and other findings including previous FLC results. However, a Kappa/Lambda Ratio <0.26 indicates probable Free Lambda producing monoclonal protein and a Ratio >1.65 indicates a probable Free Kappa producing monoclonal protein. It is not possible to identify all cases of antigen excess. A small percentage of samples in antigen excess have normal reaction kinetics so will not prompt the ‘High activity’ flag. The following therefore accompanies all results; Undetected antigen excess is a rare event but cannot be excluded. Any unexpected results or discrepancy between the serum FLC results and other laboratory tests should be reported to the laboratory so that FLC re-resting can be arranged. Please phone if you wish to discuss (01904 726366).
LimitationsTurbidity, particles and haemolysis may interfere with the assay. Samples that are visibly turbid or containing particles should be centrifuged prior to analysis. Highly lipaemic or turbid samples that cannot be clarified should not be used. • Due to the nature of monoclonal proteins, some samples may exhibit non linearity when assayed at different dilutions. In order to appropriately quantify such samples, it is advised that the result reported is the first plausible result from the least diluted sample. Microbially contaminated samples should not be used. This assay has not been established for use with the paediatric population.
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