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Mean Cell Volume

 
 
 
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Overview

The mean cell volume (MCV) is a measure of the average volume of a red blood cell.
Assessment of red blood cell size - the presence of normocytosis, microcytosis or macrocytosis - is the first step in the assessment of patients with anaemia as it can rapidly be used to narrow down the likely causes.
    • Normal Range

    • 80-100 fL
  • Interpretation

  • Microcytosis: abnormally small red blood cellsIron deficiency, anaemia of chronic disease, thalassaemia, lead poisoning
  • Normocytosis: normally sized red blood cellsAplastic anaemia, acute haemorrhage, haemolysis
  • Macrocytosis: abnormally large red blood cellsB12/folate deficiency, alcoholism, myelodysplastic syndrome

Microcytosis

Microcytosis refers to the presence of small red cells with mean corpuscular volume <80 fL.
  • Causes of Reduced Mean Cell Volume

  • Iron deficiency anaemia - nutritional deficiency, blood loss, malabsorption, pregnancy
  • Anaemia of chronic disease (chronic infection / inflammation / malignancy)
  • Thalassaemia
  • Congenital sideroblastic anaemia
  • Lead poisoning
  • Hyperthyroidism

Macrocytosis

Macrocytosis refers to the presence of large red blood cells with mean corpuscular volume >100 fL.
Macrocytic cells may occur in the context of megaloblastic anaemia, which is typically associated with macroovalocytes (large oval-shaped cells) and hypersegmented neutrophils; they may be seen due to an overabundance of reticulocytes (immature non-nucleated red cells); or may be due to other causes such as liver disease, hypothyroidism or myelodysplastic syndrome.
  • Causes of Macrocytosis

  • Megaloblastic

  • B12 deficiency
  • Folate deficiency
  • Scurvy
  • Drugs - methotrexate, chemotherapy, reverse transcriptase inhibitors, valproate, phenytoin, nitrous oxide, trimethoprim
  • Reticulocytosis

  • Haemolytic anaemia
  • Haemorrhage
  • Recovery following bone marrow suppression
  • Other

  • Chronic liver disease
  • Chronic alcohol abuse
  • Myelodysplastic syndrome
  • Post splenectomy
  • Aplastic anaemia
  • Hypothyroidism
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