93 Serum proteins have different net charges and can be separated by electrophoresis into several distinct bands; albumin, alpha 1-globulin (a1G), alpha 2-globulin (a2G), beta globulin (bG), and gamma globulins (gG). Protein concentrations may be altered as a result of different disease states. Interpretation of serum protein electrophoretic patterns is helpful in confirming the diagnosis of some diseases. The most commonly recognized electrophoretic patterns are summarized in the following table.
Pattern
Protein Changes
Frequently Associated Diseases
Acute
Inflammation
Normal or Decreased albumin
Increased a1G &/or a2Globulin
Acute infection and inflammatory disorders
Chronic
Inflammation
Normal or Decreased albumin
Increased a1G or a2Globulin
Increased gamma Globulin
Autoimmune diseases, chronic liver disease, chronic infection, cancer
Hypo-
albuminemia
Decreased albumin
Metastatic cancer, CHF, malnutrition, protein losing disorders
Hypogamma-globulinemia
Normal or decreased albumin
Decreased gamma Globulin
Normal or Decreased albumin
Increased gamma Globulin
Myeloma, macroglobulinemia, MGUS, CLL, lymphoma
Antitrypsin deficiency
absent alpha 1Globulin
Alpha 1 antitrypsin deficiency
Hyperbeta-
globulinemia
Normal – Decreased albumin
Increased beta Globulin
Hyperlipidemia, diabetes mellitus,
iron deficiency anemia
SPE Interpretation Tips
Albumin band often looks less intense on IFE compare to SPE, probably because it is incompletely fixed and elutes off the gel
Bisalbuminemia is most commonly seen in Native American individuals
Bilirubin, heparin & antibiotic binding can cause slurring of albumin band
Hemolysis causes decreased alpha-2 band (haptoglobin) and appearance of Hb band between alpha-2 and beta-1 regions
C3 is labile & decreases with storage; results in much variation in beta-2 region
Fibrinogen migrates between beta-2 and gamma regions (close to application point) and is present in plasma or heparin contaminated specimens
Immune complexes appear as monoclonal band at application point
Monoclonal bands in the beta region may indicate light chain disease, amyloidosis, heavy chain disease, IgD and IgE monoclonal gammopathies
Gamma heavy chain disease can produce a relatively broad band anywhere from the alpha-2 through the gamma region
CRP migrates in the gamma region and resembles a monoclonal band; present in acute inflammation
High resolution SPE gel can detect a monoclonal band of 0.1 g/dL
High resolution SPE cannot accurately quantitate monoclonal bands <0.3 g/dL
Oligoclonal bands with hypergammaglobulinemia & possibly beta-gamma bridging may be present in serum in patients responding to antigenic stimulation resulting from viral & bacterial infections, vaccines, autoimmune diseases and angioimmunoblastic lymphadenopathy.
Oligoclonal bands with decreased IgG level is seen in CLL, post heart and BM transplants, and common variable immunodeficiency and immunosuppressive Rx.
Infections may cause transient monoclonal proteins
Light chain disease can result in monoclonal kappa or lambda chains in serum and not in urine if light chains are polymerized
Kappa chains usually stain more strongly than lambda chains
Broader width of monoclonal bands may be related to amount of protein applied to gel or heterogeneity of monoclonal protein due to glycosylation. IgA monoclonal bands are usually broader than IgG.
A monoclonal band may be clinically significant if it is at least as intense as the alpha 1 band.
Clues that a monoclonal band is unlikely to be due to a malignant clonal expansion
Acute phase pattern is present along with monoclonal band
Monoclonal band is transient & may evolve into an oligoclonal pattern
All immunoglobulin classes are elevated along with monoclonal
Slightly abnormal kappa:lambda ratio
Bence Jones protein is absent from urine
Serum protein electrophoresis should be repeated in one year for asymptomatic patients with a monoclonal protein less than 1.5 g/dL and normal values of hemoglobin, calcium, and creatinine. Electrophoresis should be repeated in two to three months if the monoclonal protein is between 1.5 and 2.5 g/dL. Patients being treated for multiple myeloma, Waldenstrom’s macroglobulinemia or amyloidosis should be monitored at one to two month intervals.
Reference ranges are:
