Detect and Monitor Multiple Myeloma (MM) with Freelite® assays

The time-tested and proven solution for kappa and lambda serum free light chain (sFLC) analysis 


What are free light chains (FLC)?

Free light chains are produced by plasma cells - these are the cells responsible for the production of antibodies, also called immunoglobulins.

An antibody is made up of heavy chains and light chains. The heavy and light chains are bound together to form an intact immunoglobulin. 

These two proteins are produced independently and assembled within the plasma cells. 

The light chains are produced in excess and therefore they can be found also as free proteins in the serum. This is why they are called serum free light chains.

Free light chains are an excellent biomarker to evaluate the uncontrolled growth of plasma cells, typical of blood cancers such as MM, as they can often be found at concentrations proportional to the tumour burden.

Find out about serum free light chain (sFLC) protein detection

What is this test?

What are Freelite assays?

Freelite assays are based on polyclonal antisera, targeting kappa and lambda free light chains respectively.

Freelite assays are highly sensitive and specific. The analytical sensitivity and specificity of Freelite assays is achieved by the use of latex particles coated with affinity purified polyclonal antibodies.

Freelite assays can be used in serum, EDTA and lithium heparin plasma, urine, and cerebrospinal fluid (CSF) using the Binding Site Optilite® automated Analyser. 

In serum, plasma, and urine, the assay can aid in the diagnosis and monitoring of monoclonal gammopathies, such as:

  • MM including light chain multiple myeloma, oligo-secretory Multiple Myeloma and non-secretory Multiple Myeloma,
  • AL amyloidosis
  • Lymphocytic neoplasms
  • Waldenström's macroglobulinaemia (WM)
  • Light chain deposition disease (LCDD)

In CSF, the Freelite Mx assay aids in the characterization of intrathecal immunoglobulin synthesis.

Discover Freelite Mx™
Detect Intrathecal immunoglobulin synthesis

Why choose this test?

Why choose Freelite assays?

Freelite assays were the first commercially available automated FLC immunoassays, released worldwide in 2001.  

Freelite assays are used in the largest MM centers worldwide.  

Free light chain values in national and international guidelines are based on results obtained using Freelite assays.

Freelite assays use polyclonal antisera to detect the widest range of free light chains. This is important due to the large variety of free light chains that can be produced by plasma cells. 

Many studies have proven that free light chain assays are not interchangeable1,2,3, so changing assays will require patient sample re-baselining and continuity of MM monitoring is crucial. 

Decisions based on clinically proven assays minimize risk for patient management. 

Freelite assays are the most widely used free light chain tests, providing the confidence and performance you need for optimal patient management


Your trusted diagnostic assay for the management of MM

  • Freelite is the assay of choice in 1000+ laboratories worldwide, including the largest myeloma centers
  • Freelite is the most cited free light chain assay, cited in 3800+ scientific publications 
  • Freelite assays are mentioned by name in national and international guidelines. FLC values in these guidelines are based on results obtained using Freelite assays
  • The performance of Freelite assays has been established in both clinical and laboratory practice
  • Analytical performance is evaluated according to procedures based on Clinical & Laboratory Standard Institute guidelines for assay precision, linearity, and measurement interference and cross reactivity
  • Peer reviewed scientific literature demonstrates that the Freelite assays, in conjunction with other clinical and laboratory tests, show excellent diagnostic sensitivity and specificity

Freelite for guideline compliant testing

Recommended for diagnosis and monitoring of MM and AL amyloidosis

  • International Myeloma Working Group (IMWG) mention Freelite assays for diagnosis and monitoring of monoclonal gammopathies6,7. FLC values in these guidelines are based on results obtained using Freelite assays
  • The National Comprehensive Cancer Network (NCCN) recommends use of serum-free light-chain assay for diagnosis and monitoring of Multiple Myeloma8 
  • European Myeloma Network, the European Hematology Association and European Society for Medical Oncology Guidelines recommend free light-chain (sFLC) measurement for diagnosis and monitoring of Multiple Myeloma9,10
  • The UK NICE guidelines also recommend use of serum-free light-chain assay for diagnosis and monitoring of Multiple Myeloma11
  • The International Kidney and Monoclonal Gammopathy (IKMG) Research Group recommend sFLC analysis for the investigation of new, unexplained AKI in Multiple Myeloma12
  • Freelite assays are CE marked and 510k cleared in USA
MM and Monoclonal Gammopathies:

Analytical sensitivity 

Higher than traditional methods

Freelite assays detect low levels of light chains, not quantifiable by conventional methods such as SPE.11 They are able to detect free light chains even when serum or urine immunofixation may not.

Freelite assays are able to measure FLC above, within and below the reference interval. This means they can provide information on both the involved FLC and the uninvolved FLC.

Freelite assays can be ~10-fold higher sensitivity compared to uIFE.12

There are several clinical situations where sensitivity in both diagnosis and monitoring of MM is of even more importance

  • Around 20% of patients with MM have light chain myeloma – these patients have tumors which secrete free light chains only. If the tumor does not secrete a lot of FLC, they may not be detected by serum protein electrophoresis (SPE). This is why a panel of tests, including SPE and sFLC with reflex serum immunofixation electrophoresis (sIFE) testing if necessary is recommended by the International Myeloma Working Group guidelines
    • Although the amount of FLC may be small, they may still have significant nephrotoxic effects
  • In patients with AL amyloidosis, the amount of FLC secreted is often quite low, with organ damage coming from the deposition of these light chains in organs including the heart, kidney and liver. In this disease, it is even more important to use the most sensitive techniques in the diagnosis and monitoring of these patients

  • Some patients with intact immunoglobulin Multiple Myeloma (IIMM) do not secrete enough intact immunoglobulin to be accurately monitored using SPE according to IMWG guidelines. Many of these patients can be monitored using FLC, enabling guideline-compliant testing, potentially reducing the need for painful and invasive bone marrow biopsies in these patients

  • When patients with myeloma are treated, and respond to treatment, the amount of monoclonal protein secreted reduces as the tumor burden reduces. This increases the importance of having a high sensitivity method of measuring FLC, particularly where monoclonal gammopathies are suspected as the cause of AKI. FLC values in these guidelines were established in studies that used Freelite assays

  • The sensitivity of free light chains is such that normalization of the sFLC ratio is included as one of the criteria for stringent complete response in the IMWG guidelines
    • FLC values in these guidelines are based on results obtained using Freelite assays
  • In patients who relapse, the type of monoclonal protein the tumour secretes may change. This is why it is important to regularly monitor even IIMM patients with sFLC tests. It is especially important to detect a form of relapse called light chain escape. In light chain escape there is an increase in monoclonal FLC with no corresponding increase in monoclonal intact immunoglobulins

Freelite assays on the Optilite® Analyser provide the optimal laboratory solution for free light chain testing

Providing ease of use and confidence with accurate rapid results

  • Rapid results (Freelite assays on the Optilite Analyser have a turn around time of 30 minutes) 
  • Consistent, reproducible, and accurate results
  • Excellent batch to batch and lot to lot consistency and linearity
  • Access to the Optilite Analysers diverse menu of tests.
  • The Optilite Analyser enables use of unique assays such as Hevylite® assays and the automated CH50 assay
  • The Optilite Analyser allows for measurement of free light chains and heavy + light chains (HLC) through use of Freelite and Hevylite assays, providing a greater level of valuable information for optimal patient management.


Optilite is a registered trademark of The Binding Site Group Ltd (Birmingham, UK) in certain countries.
Discover the Optilite® Analyser
Transform your diagnostics with effortless workflow


Monitoring with Freelite and Hevylite

Together, ‘Freelite’ and ’Hevylite’ assays provide more information when monitoring MM, including non-secretory and oligo-secretory MM, Light Chain Multiple Myeloma (LCMM), AL amyloidosis

Freelite Hevylite
Quantifies κ and λ free light chains in serum Quantifies individual heavy + light chain (HLC) isotypes in serum.
Discordant κ/λ FLC ratio is a sensitive marker of light chain clonality Molecules are measured in pairs, e.g., IgGκ/ IgGλ, to produce HLC ratios, which can identify  plasma cell clonality
sFLC assays + SPE = diagnosis of MM HLC assays allows quantification for difficult to measure M proteins
Detects light chain escape at relapse When uninvolved HLC concentration is below the reference range this may indicate immunosuppression


AL: Amyloid light chain; CR: Complete response;  LCMM: Light chain multiple myeloma; HLC: Heavy light chain; MGUS: Monoclonal gammopathy of unknown significance; MM: Multiple Myeloma; NSMM: Nonsecretory multiple myeloma; sCR: stringent complete response; SPE: Serum Protein Electrophoresis; sFLC: serum-free light chain assay
*Only IgG and IgA Hevylite assays are indicated for monitoring only in previously diagnosed patients
Freelite® assays
Freelite® assays

When measuring free light chains, choose Freelite assays by Binding Site
What is the best test combination to rule out Multiple Myeloma?
What is the best test combination to rule out Multiple Myeloma?

Dr Joseph Mikhael on what blood tests should be ordered when Multiple Myeloma is suspected
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1. Schieferdecker, A. Blood Cancer J. 2020 Jan 9;10(1):2. doi: 10.1038/s41408-019-0267-8
2. Bossuyt, X. et al. Diagnostic thresholds for free light chains in multiple myeloma depend on the assay used. Leukemia 32, 1815–1818 (2018)
3. Caillon, H. et al. Comparison of Sebia free light chain assay with freelite assay for the clinical management of diagnosis, response, and relapse assessment inmultiple myeloma. Clin. Lymph., Myelom. Leuk. 19, e228–e237 (2019)
4. Rajkumar SV, et al. International Myeloma Working Group updated criteria for the diagnosis of multiple myeloma. Lancet Oncol 2014; 15:e538-e548
5. Kumar et al. International Myeloma Working Group consensus criteria for response and minimal residual disease assessment in multiple myeloma. Lancet Oncol 2016; 17: e328-346
6. Kumar et al. NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®): Multiple Myeloma - Version 3.2023
7. Caers J, et al. European Myeloma Network recommendations on tools for the diagnosis and monitoring of multiple myeloma: what to use and when. Haematologica. 2018;103(11):1772-1784
8. Dimopoulos et al. Multiple myeloma: EHA-ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Annals Onc. 2021; 32: 309-322
9. Myeloma: diagnosis and management. NICE Guidelines 2016
10. Hutchison, C.A., et al., The pathogenesis and diagnosis of acute kidney injury in multiple myeloma. Nat Rev Nephrol, 2011. 8(1): p. 43-51
11. Dispenzieri, A., et al., International Myeloma Working Group guidelines for serum-free light chain analysis in multiple myeloma and related disorders. Leukemia, 2009. 23(2): p. 215-224
12. Tate Ann Clin Biochem 2012;49:242-56