Hemoglobin (Hb) A2, Quantitative

CPT: 83021
Updated on 5/28/2019
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  • A2, Quantitative
  • Hb A2, Quantitative

Special Instructions

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.

Expected Turnaround Time

2 - 5 days

2 - 5 days

Related Documents

Specimen Requirements


Whole blood


1 mL

Minimum Volume

0.5 mL


Lavender-top (EDTA) tube

Lavender-top (EDTA) tube, blue-top (sodium citrate) tube, or green-top (heparin) tube

Lavender-top (EDTA) tube

) tube


To avoid delays in turnaround time, please submit a separate lavender-top tube for each test requiring a lavender-top.

Pediatric: heelstick. To avoid delays in turnaround time, please submit a separate lavender-top tube for each test requiring a lavender-top.

To avoid delays in turnaround time, please submit a separate lavender-top tube for each test requiring a lavender-top.

Storage Instructions

Refrigerate at 2°C to 8°C.

Refrigerated specimens may be stored at 4°C for seven days. Do not store as hemolysate.

Refrigerate at 2°C to 8°C.

Stability Requirements



Room temperature

14 days


14 days


14 days

Freeze/thaw cycles

Stable x3

Patient Preparation

Fasting or fluid restriction is not necessary.

Causes for Rejection

Clotted specimen

Test Details


Investigate for hemolytic anemia, hemoglobinopathies, and thalassemia


Blood transfusion prior to hemoglobin analysis may cause inconsistent interpretation.


High-pressure liquid chromatography (HPLC)

Reference Interval

See table.



<7 mo

Not established

7 mo to 1 y

1.9% to 2.8%

≥2 y

1.8% to 3.2%

Additional Information

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.


1. Wasi P, Disthasongchan P, Na-Nakorn S. The effect of iron deficiency on the levels of hemoglobins A2 and E. J Lab Clin Med. 1968 Jan; 71(1):85-91. 5635011


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

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