Abstract
Electrophoretic methods to detect, characterize and quantify M-proteins play an important role in the management of patients with monoclonal gammopathies (MGs). Significant uncertainty in the quantification and limit of detection (LOD) is documented when M-proteins are <10 g/L. Using spiked sera, we aimed to assess the variability in intact M-protein quantification and LOD across 16 laboratories. Sera with normal, hypo- or hyper-gammaglobulinemia were spiked with daratumumab or elotuzumab, with concentrations from 0.125 to 10 g/L (n = 62) along with a beta-migrating sample (n = 9). Laboratories blindly analyzed samples according to their serum protein electrophoresis (SPEP)/isotyping standard operating procedures. LOD and intra-laboratory percent coefficient of variation (%CV) were calculated and further specified with regard to the method (gel/capillary electrophoresis [CZE]), gating strategy (perpendicular drop [PD]/tangent skimming [TS]), isotyping (immunofixation/immunosubtraction [ISUB]) and manufacturer (Helena/Sebia). All M-proteins ≥1 g/L were detected by SPEP. With isotyping the LOD was moderately more sensitive than with SPEP. The intensity of polyclonal background had the biggest negative impact on LOD. Independent of the method used, the intra-laboratory imprecision of M-protein quantification was small (mean CV = 5.0%). Low M-protein concentration and high polyclonal background had the strongest negative impact on intra-laboratory precision. All laboratories were able to follow trend of M-protein concentrations down to 1 g/L. In this study, we describe a large variation in the reported LOD for both SPEP and isotyping; overall LOD is most affected by the polyclonal immunoglobulin background. Satisfactory intra-laboratory precision was demonstrated. This indicates that the quantification of small M-proteins to monitor patients over time is appropriate, when subsequent testing is performed within the same laboratory.
| Original language | English |
|---|---|
| Journal | Clinical Chemistry and Laboratory Medicine |
| DOIs | |
| Publication status | Accepted/In press - Jan 1 2020 |
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Keywords
- accuracy
- immunofixation
- immunosubtraction
- limit of detection
- monoclonal proteins
- precision
- protein electrophoresis
ASJC Scopus subject areas
- Clinical Biochemistry
- Biochemistry, medical
Cite this
An international multi-center serum protein electrophoresis accuracy and M-protein isotyping study. Part II : Limit of detection and follow-up of patients with small M-proteins. / Jacobs, Joannes F.M.; Turner, Katherine A.; Graziani, Maria Stella; Frinack, Jody L.; Ettore, Michael W.; Tate, Jillian R.; Booth, Ronald A.; McCudden, Christopher R.; Keren, David F.; Delgado, Julio C.; Zemtsovskaja, Galina; Fullinfaw, Robert O.; Caldini, Anna; De Malmanche, Theo; Katakouzinos, Katina; Burke, Matthew; Palladini, Giovanni; Altinier, Sara; Zaninotto, Martina; Righetti, Gabriella; Melki, Marie Therese; Bell, Stephen; Willrich, Maria Alice Vieira.
In: Clinical Chemistry and Laboratory Medicine, 01.01.2020.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - An international multi-center serum protein electrophoresis accuracy and M-protein isotyping study. Part II
T2 - Limit of detection and follow-up of patients with small M-proteins
AU - Jacobs, Joannes F.M.
AU - Turner, Katherine A.
AU - Graziani, Maria Stella
AU - Frinack, Jody L.
AU - Ettore, Michael W.
AU - Tate, Jillian R.
AU - Booth, Ronald A.
AU - McCudden, Christopher R.
AU - Keren, David F.
AU - Delgado, Julio C.
AU - Zemtsovskaja, Galina
AU - Fullinfaw, Robert O.
AU - Caldini, Anna
AU - De Malmanche, Theo
AU - Katakouzinos, Katina
AU - Burke, Matthew
AU - Palladini, Giovanni
AU - Altinier, Sara
AU - Zaninotto, Martina
AU - Righetti, Gabriella
AU - Melki, Marie Therese
AU - Bell, Stephen
AU - Willrich, Maria Alice Vieira
PY - 2020/1/1
Y1 - 2020/1/1
N2 - Electrophoretic methods to detect, characterize and quantify M-proteins play an important role in the management of patients with monoclonal gammopathies (MGs). Significant uncertainty in the quantification and limit of detection (LOD) is documented when M-proteins are <10 g/L. Using spiked sera, we aimed to assess the variability in intact M-protein quantification and LOD across 16 laboratories. Sera with normal, hypo- or hyper-gammaglobulinemia were spiked with daratumumab or elotuzumab, with concentrations from 0.125 to 10 g/L (n = 62) along with a beta-migrating sample (n = 9). Laboratories blindly analyzed samples according to their serum protein electrophoresis (SPEP)/isotyping standard operating procedures. LOD and intra-laboratory percent coefficient of variation (%CV) were calculated and further specified with regard to the method (gel/capillary electrophoresis [CZE]), gating strategy (perpendicular drop [PD]/tangent skimming [TS]), isotyping (immunofixation/immunosubtraction [ISUB]) and manufacturer (Helena/Sebia). All M-proteins ≥1 g/L were detected by SPEP. With isotyping the LOD was moderately more sensitive than with SPEP. The intensity of polyclonal background had the biggest negative impact on LOD. Independent of the method used, the intra-laboratory imprecision of M-protein quantification was small (mean CV = 5.0%). Low M-protein concentration and high polyclonal background had the strongest negative impact on intra-laboratory precision. All laboratories were able to follow trend of M-protein concentrations down to 1 g/L. In this study, we describe a large variation in the reported LOD for both SPEP and isotyping; overall LOD is most affected by the polyclonal immunoglobulin background. Satisfactory intra-laboratory precision was demonstrated. This indicates that the quantification of small M-proteins to monitor patients over time is appropriate, when subsequent testing is performed within the same laboratory.
AB - Electrophoretic methods to detect, characterize and quantify M-proteins play an important role in the management of patients with monoclonal gammopathies (MGs). Significant uncertainty in the quantification and limit of detection (LOD) is documented when M-proteins are <10 g/L. Using spiked sera, we aimed to assess the variability in intact M-protein quantification and LOD across 16 laboratories. Sera with normal, hypo- or hyper-gammaglobulinemia were spiked with daratumumab or elotuzumab, with concentrations from 0.125 to 10 g/L (n = 62) along with a beta-migrating sample (n = 9). Laboratories blindly analyzed samples according to their serum protein electrophoresis (SPEP)/isotyping standard operating procedures. LOD and intra-laboratory percent coefficient of variation (%CV) were calculated and further specified with regard to the method (gel/capillary electrophoresis [CZE]), gating strategy (perpendicular drop [PD]/tangent skimming [TS]), isotyping (immunofixation/immunosubtraction [ISUB]) and manufacturer (Helena/Sebia). All M-proteins ≥1 g/L were detected by SPEP. With isotyping the LOD was moderately more sensitive than with SPEP. The intensity of polyclonal background had the biggest negative impact on LOD. Independent of the method used, the intra-laboratory imprecision of M-protein quantification was small (mean CV = 5.0%). Low M-protein concentration and high polyclonal background had the strongest negative impact on intra-laboratory precision. All laboratories were able to follow trend of M-protein concentrations down to 1 g/L. In this study, we describe a large variation in the reported LOD for both SPEP and isotyping; overall LOD is most affected by the polyclonal immunoglobulin background. Satisfactory intra-laboratory precision was demonstrated. This indicates that the quantification of small M-proteins to monitor patients over time is appropriate, when subsequent testing is performed within the same laboratory.
KW - accuracy
KW - immunofixation
KW - immunosubtraction
KW - limit of detection
KW - monoclonal proteins
KW - precision
KW - protein electrophoresis
UR - http://www.scopus.com/inward/record.url?scp=85078114015&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85078114015&partnerID=8YFLogxK
U2 - 10.1515/cclm-2019-1105
DO - 10.1515/cclm-2019-1105
M3 - Article
C2 - 31940285
AN - SCOPUS:85078114015
JO - Clinical Chemistry and Laboratory Medicine
JF - Clinical Chemistry and Laboratory Medicine
SN - 1434-6621
ER -