#Red Cell Distribution Width (RDW)
The red blood cell distribution width (RDW) is a measure of variation red blood cell (RBC) size. It is easily calculated by dividing the SD of erythrocyte volumes for the mean corpuscular volume. A modern refinement is the Red Cell Distribution width (RDW), which is a measurement of the variation in size of the RBC, and attempts to give a figure to the degree of anisocytosis, this being a morphological term indicating how much the cells vary in size.
Causes of Normal RDW:
- Thalassaemia
- Acute blood loss anaemia
- Anaemia of chronic disease
- Spherocytosis
- Aplastic anaemia
- Preleukaemia
Causes of high RDW:
- Iron deficiency anemia
- Some haemolytic anaemias
- Combined anaemias
- Sickle cell anaemia
- Sideroblastic anaemia
- Chronic blood loss
- B12/folate deficiency
- Cold agglutinin