Iron Deficiency vs. Thalassemia Minor
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                    *Iron Deficiency*    *Thalassemia Minor*    *Combined*
  *MCV*                  Low                     Very Low              Very Low
  *RDW*                  High                     Normal or High       High
  *Red Cell Count*     Low                     Normal or High       Normal or Low
  *Marrow Iron*       Absent                  Normal                 Absent
  *Serum Iron*         Low                     Normal                  Low
  *TIBC*                 High                     Normal                  High
  *Serum Ferritin*     Low                     Normal                  Low
  *Hemoglobin A2*    Low                     High                     Normal
 Normal Values
   Normal Values RBC count (varies with altitude):
        Male: 4.7 to 6.1 million cells/mcL
        Female: 4.2 to 5.4 million cells/mcL
    WBC count: 4,500 to 10,000 cells/mcL
    Hematocrit (varies with altitude):
        Male: 40.7 to 50.3%
        Female: 36.1 to 44.3%
    Hemoglobin (varies with altitude):
        Male: 13.8 to 17.2 gm/dL
        Female: 12.1 to 15.1 gm/dL
    RDW <14.5%
    MCV: 80 to 95 femtoliter
    MCH: 27 to 31 pg/cell
    MCHC: 32 to 36 gm/dL

The reticulocyte count may assist in differentiating a hyporegenerative or arregenerative anemia from one due to RBC destruction (Irwin & Kirchner, 2001; Lesperance et al., 2002). An elevated reticulocyte count suggests premature release of immature RBCs into the circulation (Abshire, 2001) to replace losses from rapid destruction, as occurs in hemolytic disorders. Conversely, a low reticulocyte count in the face of anemia suggests decreased production or release of RBCs (Cohen, 1996), as may be found in bone marrow failure, iron deficiency, lead poisoning, and anemia of inflammation (Hermiston & Mentzer, 2002). Assessment of the reticulocyte count is particularly helpful in the diagnosis of anemia of prematurity, as it will be paradoxically decreased for the degree of anemia present. In addition to its diagnostic potential, the reticulocyte count may be used to guide response to anemia management, including nutritional support or exogenous erythropoietin administration (Abshire, 2001; Widness, 2000).