RDW-SD (Red Cell Distribution Width in femtolitres)
RDW-SD is the width of the red cell volume distribution in femtolitres, that is how much cells differ in size.
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Normal ranges
Adults: 35–56 fL.
Units: fL
Causes of deviations
Low levels:
Usually has no meaning.
High levels:
Iron, vitamin B12 or folate deficiency, mixed anemia.
When to see a doctor
If the value is outside the range, discuss it with your doctor.
Related biomarkers
Panels
Cbc
Conditions
Anemia
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