Hemoglobinopathy Fractionation Cascade With Reflex to α-Thalassemia

Whole blood and serum

Three lavender-top (EDTA whole blood) tubes filled to capacity and 0.8 mL serum

Two lavender-top (EDTA whole blood) tubes filled to capacity and 0.3 mL serum. (Note: This volume does not allow for repeat testing.)

Lavender-top (EDTA) tubes and red-top tube or gel-barrier tube

Diagnose thalassemias and hemoglobin variants, with ferritin to evaluate total body storage iron, and complete blood count without differential to detect and/or identify a wide range of hematologic disorders. When appropriate, additional reflex testing will be performed for α-thalassemia. DNA analysis of the α-globulin gene locus (HBA1/HBA2 OMIM 141800 and 141850,16pter-16p13.3) can detect copy-number changes by targeting 24 different sequences in the α-globulin region, and will, in principle, detect all genomic deletions and duplications involving this locus, in addition to the Constant Spring point mutation. The mutations analyzed include Southeast Asian(--SEA), Thai(--Thai), Filipino(--FIL), Mediterranean(--MED), a3.7, and a4.2.

Limitations for Ferritin: As with all tests containing monoclonal mouse antibodies, erroneous findings may be obtained from samples taken from patients who have been treated with monoclonal mouse antibodies or have received them for diagnostic purposes.¹ In rare cases, interference due to extremely high titers of antibodies to streptavidin and ruthenium can occur.¹ The ferritin test contains additives that minimizes these effects.

CBC: Automated cell counter; ferritin: electrochemiluminescence immunoassay (ECLIA); hemoglobin fractionation cascade: capillary electrophoresis (CE), high-pressure liquid chromatography (HPLC); hemoglobin solubility: sodium hydrosulfite reduction; if reflexed to α-thalassemia: polymerase chain reaction (PCR) and gel electrophoresis.

Refer to individual assays for additional information.