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RDW

A red cell distribution width (RDW) test measures how much the volume and size of your red blood cells (erythrocytes) varies.

The RDW blood test is often part of a complete blood count (CBC), a group of tests that measures the number and type of cells in your blood, including red cells. The RDW test is commonly used to help diagnose or determine what's causing anemia, a condition in which your body does not make enough red blood cells.

Source: MedlinePlus, U.S. National Library of Medicine

Normal range

37 published ranges, each from a named source
Normal
9–14.5 %
Female
12.2–16.1 %
Male
11.8–14.5 %
Ranges from American Board of Internal Medicine (Laboratory Test Reference Ranges), Mayo Clinic Laboratories (Pediatric Test Catalog), Mayo Clinic Laboratories (Test Catalog).

All source ranges (37)
SourceSexAgeRange
American Board of Internal Medicine (Laboratory Test Reference Ranges) All all ages 9–14.5 %
Mayo Clinic Laboratories (Test Catalog) Female all ages 12.2–16.1 %
Mayo Clinic Laboratories (Pediatric Test Catalog) Female all ages 12.2–16.1 %
Mayo Clinic Laboratories (Test Catalog) Female ≤ 14 d 14.6–17.3 %
Mayo Clinic Laboratories (Pediatric Test Catalog) Female ≤ 14 d 14.6–17.3 %
Mayo Clinic Laboratories (Pediatric Test Catalog) Female 15 d – 28 d 14.4–16.2 %
Mayo Clinic Laboratories (Test Catalog) Female 15 d – 28 d 14.4–16.2 %
Mayo Clinic Laboratories (Pediatric Test Catalog) Female 1 mo – 2 mo 13.6–15.8 %
Mayo Clinic Laboratories (Test Catalog) Female 1 mo – 2 mo 13.6–15.8 %
Mayo Clinic Laboratories (Pediatric Test Catalog) Female 2 mo – 5 mo 12.2–14.3 %
Mayo Clinic Laboratories (Test Catalog) Female 2 mo – 5 mo 12.2–14.3 %
Mayo Clinic Laboratories (Test Catalog) Female 6 mo – 2 y 12.7–15.1 %
Mayo Clinic Laboratories (Pediatric Test Catalog) Female 6 mo – 2 y 12.7–15.1 %
Mayo Clinic Laboratories (Pediatric Test Catalog) Female 2 y – 3 y 12.4–14.9 %
Mayo Clinic Laboratories (Test Catalog) Female 2 y – 3 y 12.4–14.9 %
Mayo Clinic Laboratories (Test Catalog) Female 3 y – 5 y 11.3–13.4 %
Mayo Clinic Laboratories (Pediatric Test Catalog) Female 3 y – 5 y 11.3–13.4 %
Mayo Clinic Laboratories (Pediatric Test Catalog) Female 6 y – 17 y 11.4–13.5 %
Mayo Clinic Laboratories (Test Catalog) Female 6 y – 17 y 11.4–13.5 %
Mayo Clinic Laboratories (Test Catalog) Male all ages 11.8–14.5 %
Mayo Clinic Laboratories (Pediatric Test Catalog) Male all ages 11.8–14.5 %
Mayo Clinic Laboratories (Pediatric Test Catalog) Male ≤ 14 d 14.8–17 %
Mayo Clinic Laboratories (Test Catalog) Male ≤ 14 d 14.8–17 %
Mayo Clinic Laboratories (Test Catalog) Male 15 d – 28 d 14.3–16.8 %
Mayo Clinic Laboratories (Pediatric Test Catalog) Male 15 d – 28 d 14.3–16.8 %
Mayo Clinic Laboratories (Pediatric Test Catalog) Male 1 mo – 2 mo 13.8–16.1 %
Mayo Clinic Laboratories (Test Catalog) Male 1 mo – 2 mo 13.8–16.1 %
Mayo Clinic Laboratories (Test Catalog) Male 2 mo – 5 mo 12.4–15.3 %
Mayo Clinic Laboratories (Pediatric Test Catalog) Male 2 mo – 5 mo 12.4–15.3 %
Mayo Clinic Laboratories (Test Catalog) Male 6 mo – 2 y 12.9–15.6 %
Mayo Clinic Laboratories (Pediatric Test Catalog) Male 6 mo – 2 y 12.9–15.6 %
Mayo Clinic Laboratories (Test Catalog) Male 2 y – 3 y 12.5–14.9 %
Mayo Clinic Laboratories (Pediatric Test Catalog) Male 2 y – 3 y 12.5–14.9 %
Mayo Clinic Laboratories (Test Catalog) Male 3 y – 5 y 11.3–13.4 %
Mayo Clinic Laboratories (Pediatric Test Catalog) Male 3 y – 5 y 11.3–13.4 %
Mayo Clinic Laboratories (Test Catalog) Male 6 y – 17 y 11.4–13.5 %
Mayo Clinic Laboratories (Pediatric Test Catalog) Male 6 y – 17 y 11.4–13.5 %

What an abnormal result can be associated with

A high result
Increased RBC distribution width
Associations from LOINC2HPO (Human Phenotype Ontology). This is reference information, not a diagnosis: only a clinician can interpret your result in context.
details
Sample
Whole blood · LOINC
Part of
CBC panel
Code
LOINC 788-0 · %
Also known as
Erythrocyte distribution width, Discocyte, Erc, Erythrocyte, RDW
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