A 59-year-old man was admitted for the investigation of mild chronic anemia (hemoglobin 11.0 g/dL). Hemoglobinopathy screening by capillary zone electrophoresis (CZE) was performed using the Capillarys Hemoglobin(e) kit (Sebia). An additional fraction in the Z(C) migration zone was observed on the electropherogram (Fig. 1).
What hypotheses can be put forward to explain the additional fraction observed in the Z(C) migration zone?
What approach should be adopted?
The answers are below.
The additional fraction observed in the Z(C) migration zone can be due to the presence of either a Hb Constant Spring variant (Hb A2: c.427T > C) or plasma proteins. Analytical interference in the form of plasma proteins is observed in anemic patients with decreased red blood cell:plasma ratios. As recommended by the manufacturer, CZE was performed on the red blood cell pellet from the same sample. The additional fraction was no longer observed, confirming plasma protein interference.
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Authors' Disclosures or Potential Conflicts of Interest: No authors declared any potential conflicts of interest.
- Received for publication March 17, 2015.
- Accepted for publication April 16, 2015.
- © 2015 American Association for Clinical Chemistry