Protein Electrophoresis (Blood)

Diagnostic Use

The test is performed to detect a paraprotein band which can be seen in various lymphoproliferative gammopathies including myeloma, Waldenström’s macroglobulinemia or MGUS.

• Gel protein electrophoresis (EPP) is performed to identify abnormal bands. Features like e.g. significant reduction in albumin, low alpha 1 (raises possibility of alpha 1- antitrypsin deficiency) and patterns suggestive of acute phase reaction, iron deficiency, nephrotic syndrome, immune suppression or interference from e.g. haemolysis will also be commented on if present.
• If an abnormal band is detected or suspected on EPP, immunofixation will be performed to identify the isotype of the band while band quantitation will be performed by Capillary zone electrophoresis (CZE).
• Immunofixation will only be performed when a new, abnormal band is detected; when a patient’s protein electrophoretic pattern changes significantly; when immunofixation is specifically requested or at pathologist discretion.
• Immunofixation is not routinely performed if the EPP pattern looks normal. However, in peripheral neuropathy for investigation (where chronic inflammatory demyelinating neuropathy is suspected) immunofixation can be useful as it has a higher sensitivity than EPP; in these cases, “NEUROPATHY – immunofixation required” should be written clearly on the request form under Clinical Details. Otherwise, immunofixation will not be test added.
• First tier immunofixation routinely identifies IgG, IgA, IgM, kappa and lambda isotypes. For newly identified unmatched kappa or lambda light chain bands, immunofixation against the rare IgD and IgE heavy chain will be tested.
• Multiple bands of the same isotype can arise from in vitro polymerisation of the IgA or IgM monoclonal protein. Treatment with depolymerising reagent (beta-mercaptoethanol) before immunofixation can help to identify polymerisation.

Band Quantitation

• Band quantitation aids monitoring patients with a quantifiable monoclonal band.
• The uncertainty of measurement for band quantitation is 15%.
• Quantitation of bands in the non-gamma region: perpendicular drop method (or selected perpendicular drop method if the reader can confidently define shoulders of the band). This gating method includes both the monoclonal band and the co-migrating normal serum proteins. This caveat (over-estimating the band quantity) is routinely stated in all such reports.
• Quantitation of bands in the gamma region: tangent skimming method.

Reference Intervals

Comment on pattern