Hemoglobin C and hemoglobin O-Arab variants can be diagnosed using the Bio-Rad Variant II high-performance liquid chromatography system without further confirmatory tests.
BACKGROUND
Current standards for laboratory accreditation from the College of American Pathologists state that when high-performance liquid chromatography (HPLC) is used as a screening test, all non-A, non-S abnormal hemoglobin (Hb) variants must be confirmed by an alternative method, including alkaline and acid electrophoresis.


OBJECTIVE
To determine whether confirmation of Hb C and Hb O-Arab variants by an alternative method is required when using the Bio-Rad Variant II HPLC system.


METHODS
We reviewed 48 478 consecutive hemoglobin identification test results performed on the Bio-Rad Variant II HPLC system during the period November 15, 2000 to January 15, 2003.


METHODS
Special Hematology Laboratory, Department of Pathology, Bellevue Hospital Center, New York, NY.


METHODS
The chromatogram patterns and retention times (RTs) for specimens containing Hb C and Hb O-Arab were analyzed. We compared the results by the HPLC method with those by the confirmatory tests (alkaline and acid electrophoresis) for both variants.


RESULTS
We identified 3668 cases of abnormal hemoglobin variants, including 660 cases of Hb C trait (17%), 5 cases of Hb O-Arab trait (0.1%), and 1 case of Hb SO-Arab (0.03%). A unique pattern of separation on the chromatogram for Hb O-Arab was revealed, presenting as 2 distinct peaks in 2 different manufacturer-defined RT windows, namely, D and C. The chromatogram for Hb C did not show the D window in any of the reviewed cases. The RT in the C window (C-RT) revealed a statistically significant difference for Hb C and Hb O-Arab (5.18 +/- 0.01 minutes and 4.91 +/- 0.01 minutes, respectively; P <.001).


CONCLUSIONS
According to our review, the identification of Hb C and Hb O-Arab is accurate using HPLC methodology, as performed by the Bio-Rad Variant II HPLC system. This method can be both confirmatory and diagnostic at the same time.
Joutovsky
Alla
A
Department of Pathology, New York University School of Medicine and Bellevue Hospital Center, New York, NY 10016, USA.
Nardi
Michael
M
D001797:Blood Protein Electrophoresis; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003937:Diagnosis, Differential; D004588:Electrophoresis, Cellulose Acetate; D006444:Hemoglobin C / Q000032:analysis*; D006445:Hemoglobin C Disease / Q000097:blood / Q000175:diagnosis*; D006452:Hemoglobinometry / Q000592:standards; D006453:Hemoglobinopathies / Q000097:blood / Q000175:diagnosis*; D006455:Hemoglobins, Abnormal / Q000032:analysis*; D006801:Humans; D011237:Predictive Value of Tests; D012189:Retrospective Studies
D006455:Hemoglobins, Abnormal; D006444:Hemoglobin C; C032031:hemoglobin Arab