The method for serum Free Light Chains changed on 14th July 2025. The new method (Sebia) typically produces lower results than the old method (freelite). It is not possible to directly convert results between the two methods. For this reason, one or two results will be dual reported using both methods for patients currently being monitored.
The myeloma defining event criteria of involved free light chain ratio of 100 or more and the 20-20-20 progression criteria of involved free light chain ratio of 20 remains the same with similar diagnostic accuracy (Blood Cancer J. 2022; 2;12(9):127).
Response criteria remain the same and good concordance has been demonstrated between the two assays (Clin Lymphoma Myeloma Leuk. 2019; 19(5):e228-e237).
There is a higher kappa/lambda reference interval in chronic kidney disease (CKD) of 0.46 – 2.23 (this is equivalent to the freelite method CKD reference interval of 0.37 – 3.1) (Clin Chem Lab Med. 2018; 56(9):e232-e234).
Serum
mg/L
See report
Monitoring of patients with Multiple Myeloma and diagnosis of non secretory myeloma and light chain disease
7 days
Local test
Can be added on to an existing request up to 4 days following sample receipt
21 days
Specimen Labelling Procedure
8210
