Hemoglobin A2 (Hb A2)
Hemoglobin A2 is composed of two alpha and two delta chains. The level of Hb A2 increases gradually through the first year of life at which time adult levels are reached. Elevated levels (3.5?7.0%) of Hb A2 are seen with beta thalassemia trait. Several abnormal hemoglobins including Hb S, E, C and O may cause spurious elevation. To avoid misinterpretation, hemoglobin electrophoresis should be run on all samples. Hb A2 may be increased with megaloblastic anemia and decreased with iron deficiency anemia.
Adult reference range is 0.0?3.5%.
Specimen requirement is one lavender top (EDTA) tube of blood.
