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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.
Lavender-top (EDTA) tube, blue-top (sodium citrate) tube, or green-top (heparin) tube
Fasting or fluid restriction is not necessary.
Pediatric: heelstick. To avoid delays in turnaround time, please submit a separate lavender-top tube for each test requiring a lavender-top.
Refrigerated specimens may be stored at 4°C for seven days. Do not store as hemolysate.
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|