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Blood Film

Red Blood Cell Colour

February 15th, 2021


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 >1/3 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
  • 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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