Clinical Pathology: General Principles, Clinical Chemistry

302) Serum protein and IFE patterns were obtained for a 65-year-old man with a chronic history of fatigue and back pain. Protein fractions are shown in the figures and table. Which one of the following represents the best interpretation of these patterns?

Protein Fractions Determined by Serum Protein Electrophoresis

Protein Fractions Results, g/dL Reference Range, g/dL
Albumin 2.9 3.6–4.8
Alpha-1 0.3 0.2–0.4
Alpha-2 0.7 0.6–0.9
Beta 0.9 0.6–1.0
Gamma 2.2 0.8–1.8
Total Protein 7.0 6.7–8.6

• A narrow band (i.e., a spike) in the serum protein electrophoresis (SPEP) may not be due to a monoclonal protein. Fibrinogen will migrate in the beta-gamma region and appear as a monoclonal protein in the SPEP. If immunofixation electrophoresis (IFE) is performed on this sample and a monoclonal protein is not detected, protein electrophoresis should be repeated using another serum sample.

• Fibrinogen may be present in the “serum” sample if the blood has not been allowed to clot for a sufficient amount of time. If the patient is receiving an anticoagulant that prevents complete clotting, the sample is collected in a tube that contains an anticoagulant.

• A narrow band in the SPEP can be confirmed to be fibrinogen by performing IFE using antibodies to fibrinogen or by treating the sample with thrombin followed by SPEP; in the latter case, the band will disappear.

• At very high concentrations of C-reactive protein (CRP), a small band may appear in the gamma globulin region of the SPEP.

• A narrow band may appear at the application point and in all lanes on the IFE gel because of the presence of pentameric IgM aggregates or from polymerized IgA. This sample can be treated with 2-mercaptoethanol to break up these polymers. An IFE on the treated sample will then determine whether a monoclonal protein is present.

• In cases of severe hemolysis, formation of a hemoglobin-haptoglobin complex may appear as a monoclonal band in the beta globulin region of the SPEP. Visual inspection of the specimen will reveal gross hemolysis.

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