Blood Film

Red Blood Cell Colour



  • The intensity of the colour of red blood cells is representative of the red blood cell haemoglobin concentration.


  • Hypochromia refers to a reduction in the intensity of red blood cell colour.
    • Hypochromia
    • Signs of Hypochromia

    • An increase in central pallor >⅓ of the cell on blood film
    • Reduced red cell haemoglobin (MCH / MCHC)
    • Hypochromia
    • Causes of Hypochromia

    • Microcytic

    • Iron deficiency anaemia
    • Anaemia of chronic disease (infection / inflammation / malignancy)
    • Thalassaemia
    • Congenital sideroblastic anaemia
    • Lead poisoning
    • Hyperthyroidism
    • Macrocytic

    • Copper deficiency


  • Hyperchromia refers to an increase in the intensity of red blood cell colour. Hyperchromic cells may be spherocytes, microspherocytes or macrocytes.
    • Hyperchromia
    • Signs of Hyperchromia

    • Reduction in central pallor on blood film
    • Increased red cell haemoglobin (MCH / MCHC)
    • Causes of Hyperchromia

    • Spherocytosis - hereditary spherocytosis, immune haemolysis, Clostridium
    • Microspherocytosis - microangiopathic haemolytic anaemia, severe burns
    • Macrocytosis - B12/folate deficiency chronic liver disease, alcohol abuse, hypothyroidism, post splenectomy, aplastic anaemia, myelodysplastic syndrome


  • Polychromasia refers to macrocytic (large) red blood cells with a bluish tinge, due to residual RNA. These cells are likely reticulocytes, which are immature non-nucleated red cells which have only just extruded their nuclei.
    • Polychromasia
  • This finding may occur in the context of haemolysis, though may also be seen during recovery following haemorrhage or bone marrow suppression (such as following cytotoxic chemotherapy).
    • Causes of Polychromasia

    • Haemolytic anaemia
    • Haemorrhage (acute or chronic)
    • Recovery post bone marrow suppression
    • Late pregnancy
    • High altitude
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