Monoclonal Gammopathies and Multiple Myeloma:

Challenges with traditional monitoring

Monitoring of monoclonal proteins in MM is based on the concept of measurable disease.

If a patient with myeloma produces monoclonal protein measurable by serum protein electrophoresis (SPEP) (≥10 g/L (1 g/dL)) or urine protein electrophoresis (UPEP) (≥200 mg/24-hour urine), then the International Myeloma Working Group (IMWG) recommends regular monitoring with these methods.1

If a patient is not measurable by these methods at baseline, but has an involved serum free light chain (sFLC) of at least 100 mg/L and an abnormal sFLC ratio, the patient may be monitored by sFLC according to IMWG guidelines.1


Multiple Myeloma (MM) and the Monoclonal Gammopathies that precede it can be challenging to monitor using traditional methods for several reasons2


Electrophoretic methods may not be sensitive enough to detect small changes in monoclonal protein levels, especially in early stages of the disease. This can cause false negative results, leading to delays in detecting underlying disease and in initiation of treatment.2


Electrophoresis is prone to a range of problems; monoclonal proteins can co-migrate with other serum proteins making quantification difficult. Besides this, precipitation of proteins in the sample, dye saturation, non-linearity and broad or multiple peaks on the gel can make quantification of monoclonal proteins very challenging.


SPEP and IFE (immunofixation electrophoresis) rely on subjective interpretation of protein bands, and subtle changes may be missed or interpreted as background noise. This can cause inaccuracies and potentially impact the quality of results.3,4,5

Variability and subjectivity

Another challenge is the variability and subjectivity in interpretation of SPEP and IFE results, this inter-observer variability can lead to inconsistent results between laboratories. This can be a particular concern when monitoring patients, as changes in protein levels may be difficult to interpret if there is inconsistency in how the results are interpreted.3,4

Time consuming and labor intensive

In addition, SPEP and IFE are time-consuming and labor-intensive. Samples must be processed and analysed in a timely manner and repeated testing may be required to confirm results or detect changes over time. This can become a burden on laboratory resources and increase healthcare costs for the patients.3,4

To address these challenges, Freelite® assays can be used

to measure serum free light chain (sFLC) assays can be used alongside electrophoretic methods even when monoclonal protein measurable by serum protein electrophoresis (SPEP) (≥10 g/L (1 g/dL)) or urine protein electrophoresis (UPEP) (≥200 mg/24-hour urine).

Find out more about how you can use Freelite assays
Monitoring and diagnosing MM and AL Amyloidosis

Hevylite® assays can be used

to monitor the changes in the involved immunoglobulin by their unique quantification of IgG, IgA and IgM heavy and light chain isotypes.3,4,5 These techniques offer improved analytical sensitivity compared to traditional SPEP and IFE methods and may aid in the monitoring of patients over time.3,4

Freelite® and Hevylite® assays should be used in conjunction with SPEP and IFE as they offer clinicians and laboratory professionals advanced monitoring tools to allow objective quantification of monoclonal proteins, and measurement at lower concentrations than traditional methods, for the best possible care for their patients6, 7. 

Freelite and Hevylite assays
The optimal combination for the management of monoclonal gammopathy patients
Freelite® assays
Freelite® assays

Detect and monitor Multiple Myeloma with Freelite assays
Hevylite® assays
Hevylite® assays

Analyze Heavy/Light Chain Istotype with Hevylite assays

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Abbreviations and Acronyms

Heavy-light chain




Multiple myeloma


International Myeloma Working Group


Serum protein electrophoresis


urine protein electrophoresis

1. Kumar S, et al. International Myeloma Working Group consensus criteria for response and minimal residual disease assessment in multiple myeloma. Lancet Oncol 2016; 17:e328-46
2. Keren DF. Protein electrophoresis in clinical diagnosis. 2012, ASCP Press.
3. Keren DF & Schroeder L. Challenges of measuring monoclonal proteins in serum. Clin Chem Lab Med 2016; 54:947-961
4. Prisi S, et al. Unraveling the Possibilities of Monoclonal Protein Migration, Identification, and Characterization in SPEP on Capillary Zone Electrophoresis. J Lab Physicians 2022; 14:505-510
5. Katzmann JA, et al. Serum reference intervals and diagnostic ranges for free kappa and free lambda immunoglobulin light chains: relative sensitivity for detection of monoclonal light chains. Clin Chem 2002; 48:1437-144
6. Dejoie T, et al. Responses in multiple myeloma should be assigned according to serum, not urine, free light chain measurements. Leukemia 2019; 33:313-318
7. Michallet M, et al. Heavy+light chain monitoring correlates with clinical outcome in multiple myeloma patients. Leukemia 2018; 32:376-382