Overview
SPEP separates serum proteins by charge in a gel or capillary system to detect monoclonal spikes.
Clinical Importance
Investigate high globulin, unexplained anemia, or suspected plasma-cell disorders
Specimen Requirements
- Specimen: serum or lithium heparin plasma (method- and analyzer-dependent; follow the performing laboratory)
- Tube: gold/SST (serum separator) or green-top lithium heparin as validated locally
- Handling: invert gently; allow SST to clot fully before centrifugation; separate promptly
- Storage: refrigerate serum/plasma if testing is delayed per analyte stability limits
- Stability: analyte-specific; do not exceed institutional or manufacturer time/temperature limits
- Fasting: follow institutional/protocol fasting requirements when the ordered pathway requires fasting
Analytical Method
Agarose gel or capillary zone electrophoresis with densitometry; immunofixation/immunosubtraction characterizes bands.
Instruments Used
Automated analyzers
- Capillary electrophoresis systems (e.g., Sebia Capillarys-class platforms)
- Automated gel electrophoresis analyzers
Manual methods
- Manual agarose gel electrophoresis with densitometry
Reference Values
Typical adult SI examples below follow widely published international clinical chemistry practice (e.g., Tietz; Henry's). Always interpret against the method- and demographics-specific interval printed on the patient report (CLSI EP28-A3c). Neonatal, pediatric, pregnancy, and assay-generation intervals differ.
Fraction percentages/concentrations are method-specific. Monoclonal proteins are reported quantitatively when present; no single universal M-protein cutoff.
Interpretation
Common Causes of Increased Results
- Monoclonal spike (M-protein) or polyclonal hypergammaglobulinemia patterns
Common Causes of Decreased Results
- Hypogammaglobulinemia pattern; correlate clinically
Clinical Significance
- Monoclonal protein detection
- Protein disorder screening
Factors Affecting Results
Pre-analytical
- Hemolysis, lipemia, or icterus (analyte- and method-dependent interference)
- IV fluid contamination or draw above an infusion
- Prolonged tourniquet time; delayed separation of cells
- Wrong tube additive or incomplete clotting of SST
Analytical
- Calibration/QC failure; reagent lot shifts
- Carryover or substrate depletion on high-throughput analyzers
- Assay-specific interference (heterophile antibodies for immunoassays)
Post-analytical
- Wrong reference interval or unit applied
- Failure to review delta checks / critical values before release
Advantages and Limitations
Advantages
- Visualizes monoclonal proteins
Limitations
- Small M-proteins may need immunofixation/FLC
- Not a stand-alone diagnosis of myeloma
Clinical Pearls
A suspicious SPEP spike is incomplete without immunofixation (or capillary immunosubtraction).
References
Authoritative textbooks, guidelines, and reviews supporting this laboratory test reference. Verify reference intervals, critical limits, and method details against institutional protocols and current guideline editions.
Textbooks
- Rifai N, Horvath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 8th ed. Elsevier; 2022.
- McPherson RA, Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Elsevier; 2021.
- Bishop ML, Fody EP, Schoeff LE. Clinical Chemistry: Principles, Techniques, and Correlations. 9th ed. Jones & Bartlett; 2022.
CLSI and Professional Guidelines
- International Federation of Clinical Chemistry and Laboratory Medicine (IFCC). Recommendations and reference measurement systems for clinical chemistry measurands (verify current IFCC documents for the analyte).
- Clinical and Laboratory Standards Institute. Defining, Establishing, and Verifying Reference Intervals in the Clinical Laboratory; Approved Standard. CLSI document EP28-A3c. CLSI; 2010.
- Clinical and Laboratory Standards Institute. Collection of Diagnostic Venous Blood Specimens. CLSI standard GP41. CLSI.
- American Diabetes Association. Standards of Care in Diabetes. Diabetes Care (annual update).
- Kidney Disease: Improving Global Outcomes (KDIGO). Clinical Practice Guideline for Evaluation and Management of Chronic Kidney Disease.
- American Association for the Study of Liver Diseases (AASLD). Practice guidance related to evaluation of abnormal liver chemistries / liver disease laboratory evaluation (verify current AASLD publication and institutional adoption).
Frequently Asked Questions
Common questions about using this Serum Protein Electrophoresis (SPEP) laboratory test Medical Laboratory Library reference in Medical Laboratory Science education.
What is the Serum Protein Electrophoresis (SPEP) laboratory test reference used for?
This Medical Laboratory Library page summarizes the clinical importance of Serum Protein Electrophoresis (SPEP). Review the Clinical Importance section for why the test is ordered in laboratory medicine practice.
Where can I find Serum Protein Electrophoresis (SPEP) specimen requirements?
See the Specimen Requirements section on this page for specimen information related to Serum Protein Electrophoresis (SPEP). Confirm collection details against your laboratory protocol.
Where are Serum Protein Electrophoresis (SPEP) reference values listed?
See the Reference Values section on this Laboratory Library page. Reference ranges can vary by method and population, so verify intervals with your laboratory.
How do I interpret Serum Protein Electrophoresis (SPEP) results?
Use the Interpretation section for laboratory interpretation framing, including increased and decreased result patterns when provided. Do not treat educational text as a patient-specific diagnosis.
What analytical method is used for Serum Protein Electrophoresis (SPEP)?
See the Analytical Method section for principle and method notes. Method details may differ by instrument and institutional SOP.
Are related laboratory tests linked from Serum Protein Electrophoresis (SPEP)?
Yes. The Related Laboratory Tests section lists connected references for continued lookup in the Medical Laboratory Library.
How can I continue learning after reading Serum Protein Electrophoresis (SPEP)?
Use Continue learning links on this page for related Academy lessons, medical laboratory quizzes, or laboratory case studies when available for this Clinical Chemistry topic.
What are the clinical pearls for Serum Protein Electrophoresis (SPEP)?
See the Clinical Pearls section for concise laboratory practice notes associated with Serum Protein Electrophoresis (SPEP). Apply pearls alongside institutional protocols.
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