What is macrocytosis?

Updated: Dec 16, 2020
  • Author: Vincent E Herrin, MD, FACP; Chief Editor: Emmanuel C Besa, MD  more...
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Macrocytosis is a term used to describe erythrocytes that are larger than normal, typically reported as mean cell volume (MCV) greater than 100 fL. The amount of hemoglobin increases proportionately with the increase in cell size. Therefore, if the increase in MCV is not related to macrocytic anemia, the mean cell hemoglobin concentration (MCHC) also increases in proportion. [1] Increased MCV is an indication of macrocytic anemia when any of the following is present [2] :

  • In nonpregnant females, hemoglobin < 12 g/dL or hematocrit (Hct) < 36%
  • In pregnant females, hemoglobin < 11 g/dL
  • In males, hemoglobin < 13 g/dL or Hct < 41%

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