Test Id : QMPTS

Only orderable as part of a profile. For more information see QMPSS / Monoclonal Protein Study, Quantitative, Serum.

This test is only orderable as part of a profile. For more information see QMPSS / Monoclonal Protein Study, Quantitative, Serum.

Only orderable as part of a profile. For more information see QMPSS / Monoclonal Protein Study, Quantitative, Serum.

Patient Preparation: None indicated

Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 1 mL

Collection Instructions: Centrifuge and aliquot serum into a plastic vial.

Aiding in the diagnosis and monitoring of monoclonal gammopathies if used in conjunction with free light chain studies

This test alone is not considered an adequate screen for monoclonal gammopathies.

Only orderable as part of a profile. For more information see QMPSS / Monoclonal Protein Study, Quantitative, Serum.

Monoclonal gammopathy is a general term which includes a spectrum of diagnoses including malignancies of plasma cells or B-cells (e.g. multiple myeloma [MM], Waldenstrom’s macroglobulinemia, plasmacytoma, and B-cell lymphomas and leukemias), symptomatic disorders directly related to the M-protein (eg, immunoglobulin light chain (AL) amyloidosis, light chain deposition disease, cryoglobulinemia, monoclonal gammopathy of clinical significance (MGCS), monoclonal gammopathy of renal significance (MGRS), monoclonal gammopathy of thrombotic significance (MGTS) and POEMS syndrome) and asymptomatic premalignant conditions (eg, monoclonal gammopathy of undetermined significance [MGUS] and smoldering MM). While the identification of the monoclonal gammopathy is a laboratory diagnosis, the specific clinical diagnosis is dependent on several other laboratory and clinical assessments.

Monoclonal proteins (M-proteins) are the marker of monoclonal gammopathies. An M-protein is defined by the presence of a monoclonal immunoglobulin which is expressed above the polyclonal background. The International Myeloma Working Group (IMWG) guidelines state that to adequately document the presence of a monoclonal protein, a serum protein electrophoresis (SPEP), serum free light chain (FLC) analysis, and serum immunofixation electrophoresis (IFE) or serum mass spectrometry, should all be used. If AL amyloidosis is suspected, a 24-hour urine monoclonal protein study should be performed when all serum testing is negative.

Mass-Fix has been demonstrated to be more analytically and clinically sensitive than IFE in detecting M-proteins. Mass-Fix results have also been shown to better predict patient’s progression free survival time than IFE in treated MM patients. In addition, Mass-Fix can detect M-proteins with glycosylated light chains which were demonstrated to be a risk factor for AL-amyloidosis, cold agglutin disease, and MGUS progression. When MALDI-TOF MS results are combined with quantitative immunoglobulin measurements, the assay can replace traditional SPEP for M-protein quantitation for common M-protein isotypes IgG, IgA and IgM. M-proteins which consist of only light chains are best quantitated using serum free light chains measurements.

If a monoclonal protein pattern is detected by Mass-Fix or serum FLC measurements, a diagnosis of a monoclonal gammopathy is established. The patient should be assessed clinically for symptomatic conditions such as multiple myeloma and the other diagnoses listed above. Once symptomatic disease is ruled out, a diagnosis of MGUS can be established. The IMWG guidelines suggests follow-up M-protein testing at 6 months for the first two years following a MGUS diagnosis. If the M-protein concentration remains stable over this period (ie, less than 0.5 g/dL increase) and the patient remains asymptomatic, testing can reduce to once per year.

The Iceland Screens, Treats, or Prevents Multiple Myeloma (iStopMM) study involving 75,422 participants has online resources to predict the chance that a bone marrow biopsy will have greater than 10 percent plasma cells given the isotype, M-protein concentrations, free light chain ratio and total IgG, IgA and IgM. This could be an important resource for physicians trying to decide if their patient should have a follow up bone marrow evaluation. https://istopmm.com/riskmodel/

Only orderable as part of a profile. For more information see QMPSS / Monoclonal Protein Study, Quantitative, Serum.

M-protein Isotype Flag:

Negative

Interpretation:

No monoclonal protein detected.

Immunoaffinity purification followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is performed to identify the immunoglobulin heavy and light chains.

The assay examines the mass-to-charge distributions of Ig light chains derived from immunoglobulin G, immunoglobulin A, immunoglobulin M, kappa, and lambda immunopurified from patient serum. Over-expressed Ig (ie, M-proteins or paraproteins) are detected as distinct peaks in the mass-to-charge distributions. Quantitation is accomplished by calculating the percent of monoclonal protein in the charge-to-mass distribution and multiplying this by Ig concentration as measured immunonephelometry.

Quantitation of immunoglobulin D (IgD), immunoglobulin E (IgE), free kappa and free lambda cannot be performed by this assay. Free light chain M-proteins should be quantified using test code FLCS / Immunoglobulin Free light Chains, S. The IgD and IgE should be quantified using test code IgD / Immunoglobulin D (IgD), S or IgE / Immunoglobulin E (IgE), S.

1. Rajkumar SV, Kyle RA, Therneau TM, et al. Serum free light chain ratio is an independent risk factor for progression in monoclonal gammopathy of undetermined significance. Blood. 2005;106(3):812-817

2. Katzmann JA, Dispenzieri A, Kyle RA, et al. Elimination of the need for urine studies in the screening algorithm for monoclonal gammopathies by using serum immunofixation and free light chain assays. Mayo Clin Proc. 2006;81(12):1575-1578

3. Mills JR, Kohlhagen MC, Dasari S, et al. Comprehensive assessment of M-proteins using nanobody enrichment coupled to MALDI-TOF mass spectrometry. Clin Chem. 2016;62(10):1334-1344

4. Milani P, Murray DL, Barnidge DR, et al. The utility of MASS-FIX to detect and monitor monoclonal proteins in the clinic. Am J Hematol. 2017;92(8):772-779. doi:10.1002/ajh.24772

M-protein isotype by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is performed with immunoaffinity purification followed by MALDI-TOF MS analysis. For the immunoaffinity purification, patient serum is applied to 5 separate immunoaffinity resins specific to immunoglobulin G, A, M, K, and L. Unbound protein is washed away and the isolated immunoglobulins are broken down in to their reduced to separate the heavy and light chains subunits to be analyzed via MALDI-TOF MS. The 5 separate spectra from each specimen immunopurification are overlaid and investigated for an overabundance of immunoglobulin and immunoglobulin light chain. Monoclonal protein peaks are integrated based on the modeled polyclonal background. The quantitative value is determined based on the percent area and nephelometric value of the corresponding immunoglobulin.(Milani P, Murray DL, Barnidge DR, et al. The utility of MASS-FIX to detect and monitor monoclonal proteins in the clinic. Am J Hematol. 2017;92(8):772-779. doi:10.1002/ajh.24772)

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This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

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