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- A2, Quantitative
- Hb A2, Quantitative
Investigate for hemolytic anemia, hemoglobinopathies, and thalassemia
Blood transfusion prior to hemoglobin analysis may cause inconsistent interpretation.
High-pressure liquid chromatography (HPLC)
7 mo to 1 y
1.9% to 2.8%
1.8% to 3.2%
Hemoglobin A2 levels have special application to the diagnosis of β-thalassemia trait, which may be present even though peripheral blood smear is normal. (This reflects the underlying genetic spectrum of β-thalassemia, which in reality is a complex of 20 to 30 distinct conditions.) The microcytosis and other morphologic changes of beta-thalassemia trait must be differentiated from iron deficiency. Low MCV may include the majority of β-thalassemia trait patients but does not differentiate iron deficient individuals. Low Hb A2 levels occur in untreated iron deficiency. If the β-thalassemia is associated with iron deficiency, the Hb A2 level falls, making the differentiation even more difficult (corrected after iron therapy).1 The most definitive evidence for presence of β-thalassemia trait is genetic (family study). Offspring of a person with thalassemia major will have beta-thalassemia trait. Hb A2 may be increased in megaloblastic anemia and may be decreased in sideroblastic anemia, Hb H disease, and erythroleukemia.
Pediatric: heelstick. To avoid delays in turnaround time, please submit a separate lavender-top tube for each test requiring a lavender-top.
Causes for Rejection
Specify on the request form the patient's race or ethnic origin (if known) as well as the date of any transfusions administered within the preceding three months.
|Order Code||Order Code Name||Order Loinc||Result Code||Result Code Name||UofM||Result LOINC|
|121020||Hgb A2, Quant||34660-1||121705||Hgb A2||%||34660-1|