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Lesson 9-1
Diagnosing Anemia


Physicians and clinical laboratory scientists counted RBC’s in measured volumes to detect anemia or polycythemia. Anemia means loss of oxygen-carrying capacity and is often reflected in a reduced RBC count. Polycythemia means an increased RBC count related to increase body RBC mass.

Major laboratory manifestations of anemia:

  • Decreased hemoglobin (Hgb) concentration.
  • Reduced packed cell volume hematocrit (Hct).
  • Decreased number of RBCs/L.

Laboratory testing procedures for assessing anemia:

  • Hemoglobin and hematocrit - most widely used.
  • Red blood cell count.
  • Red blood cell indices:
    • Calculations used to define the size of and hemoglobin concentration within red blood cells.
    • May be calculated manually but are usually calculated by automated instruments.
    • RBC indices, combined with an examination of the RBCs on a stained smear, tell the examiner whether the RBCs are normocytic, microcytic, macrocytic (size related), and normochromic, or hypochromic (Hgb content related).


Mean Corpuscular Volume (MCV):

  1. Indicates the average volume of the RBCs in femtoliters (fL).

  2. Expressed in SI units as femtoliter (fL; 1 fL = 10–15 L).
  3. Formally expressed as microliter (μ3L).
  4. Formula:


  1. Example

  1. Reference range: 80 to 100 fL.

Mean Corpuscular Hemoglobin (MCH):

  1. Indicates the average weight (content) of hemoglobin in a RBC.
  2. Expressed in SI units as picograms (pg; 1 pg = 10-12 g).
  3. Formula

  1. Example: RBC = 4.2 x 1012 RBCs/L

  1. Reference range: 27 to 31 pg.

Mean Corpuscular Hemoglobin (MCH):

(1) Indicates the average weight (content) of hemoglobin in a RBC.

(2) Expressed in SI units as picograms (pg; 1 pg = 10-12 g).

(3) Formula:

(4) Example:

(5) Reference range: 27 to 31 pg.

Mean Corpuscular Hemoglobin Concentration (MCHC):

  1. Calculated from Hemoglobin and Hematocrit and is an expression of the average concentration of hemoglobin in the RBC.
  2. Expressed in SI units as g/dL.
  3. Formerly expressed as percent (%).
  4. Formula:

  1. Example:

  1. Reference range: 31 to 36 g/dL (or %).


MCV and Expected RBC Morphology.

  • Elevated MCV (100 fL) – Macrocytic RBCs.

  • Normal MCV (80 – 100 fL) – Normocytic RBCs.

  • Decreased MCV ( 80 fL) – Microcytic RBCs.

MCH and Expected RBC Morphology.

  • Elevated MCH (31 pg) - usually macrocytic/normochromic RBCs.

  • Normal MCH (27 – 31 pg) - usually normocytic/normochromic RBCs.

  • Decreased MCH (27 pg) - variable macrocytic to microcytic / normochromic to hypochromic RBCs.

NOTE: MCH rarely used alone; results should be correlated with MCV and MCHC.

MCHC and Expected RBC Morphology.

  • Elevated MCHC (36 g/dL) – Normochromic never use the misnomer “hyperchromic”:

    • Hereditary spherocytosis.

    • Usually MCHC does not rise above 37 g/dL - at 37 g/dL, hemoglobin becomes gel-like and at higher concentrations crystallization may occur.

    • If greater than 38 g/dL, check specimen for cold agglutinins and lipemia. Lipemia may cause falsely elevated hemoglobin values, thus elevating the MCHC calculations.

  • Normal MCHC (31 – 36 g/dL) -- normochromic RBCs.

  • Decreased MCHC ( 31 g/dL) -- hypochromic RBCs.
NOTE: RBC color intensity is directly proportional to the cell's hemoglobin concentration. When reviewing a peripheral smear, the color of the RBCs should correspond to the MCHC value.


David L. Heiserman, Editor

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Revised: June 06, 2015