The Red Cell Distribution Width (RDW) is the coefficient of variation of the red blood cell size as determined on automated blood cell counting instruments. It is a measure of anisocytosis. It has limited value in patients without anemia.
RDW in percent =
= (standard deviation of red blood cell size) / (mean corpuscular volume)
where:
• mean corpuscular volume (MCV) is in femtoliters
Interpretation:
• normal newborns: 13.0 - 18.0 per cent
• normal 1-23 months: 11.5 - 16.0 per cent
• normal 2 - 9 years: 11.5 - 15.0 percent
• normal > 10 years: 11.5 - 14.5 per cent
Classification of Anemia based on RDW and MCV
|
RDW |
MCV |
Disorder |
|
low |
low |
thalassemia minor |
|
normal |
low |
thalassemia minor anemia of chronic disease |
|
high |
low |
iron deficiency anemia hemoglobin H disease hemoglobin S-beta thalassemia hemoglobin AC red cell fragmentation anemia of chronic disease |
|
normal |
normal |
normal anemia of chronic disease hereditary spherocytosis hemoglobin AS |
|
high |
normal |
early iron deficiency early vitamin B12 or folate deficiency sickle cell anemia hemoglobin SC |
|
normal |
high |
aplastic anemia myelodysplastic syndrome |
|
high |
high |
deficiency of vitamin B12 or folate immune hemolytic anemia cold agglutinins alcoholism |
where:
• See also 03.35.02.
Purpose: To use the RDW and MCV to suggest the likely cause for anemia.
Specialty: Hematology Oncology, Clinical Laboratory
Objective: laboratory tests, other testing
ICD-10: D50-D53, D55-D59, D60-D64, D65-D69, D70-D77,
