Red Blood Cell Colour
Overview
- The intensity of the colour of red blood cells is representative of the red blood cell haemoglobin concentration.
Hypochromia
- Hypochromia refers to a reduction in the intensity of red blood cell colour.
Signs of Hypochromia
- An increase in central pallor >⅓ of the cell on blood film
- Reduced red cell haemoglobin (MCH / MCHC)
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
- Hyperchromia refers to an increase in the intensity of red blood cell colour. Hyperchromic cells may be spherocytes, microspherocytes or macrocytes.
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
- 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.
- 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
Last updated on March 30th, 2020
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