Red Cell Distribution Width (RDW) Blood Test – Detect Anemia Subtypes
Erc(B)-RDW (Red Cell Distribution Width) analyzes the variation in size among your red blood cells. Healthy individuals have relatively uniform cell sizes. When cells vary greatly (anisocytosis), it often points to nutritional deficiencies, bone marrow disorders, or mixed anemias. RDW is typically interpreted alongside MCV, hemoglobin, and hematocrit.
Why Test Red Cell (RDW) Blood Test?
RDW is particularly useful for distinguishing between types of anemia. For example, iron-deficiency anemia often shows high RDW with low MCV, while thalassemia shows normal RDW with low MCV. The test also helps evaluate nutritional status and monitor recovery from anemia treatment.
What Do High Red Cell (RDW) Blood Test Levels Mean?
A high RDW indicates large variation in red blood cell size (anisocytosis). This may occur with iron deficiency, combined iron and B12/folate deficiency, recovery from blood loss, hemolytic anemia, or bone marrow disorders.
What Do Low Red Cell (RDW) Blood Test Levels Mean?
A normal or low RDW suggests uniform red blood cell size and is typical in healthy individuals. Some anemias, such as thalassemia minor, also present with normal RDW.
Symptoms to Watch For
- Fatigue and pallor
- Dizziness
- Shortness of breath
- Weakness
- Cold extremities
- Difficulty concentrating
Who Should Get Tested?
- People with suspected anemia
- Those with fatigue, pallor, or dizziness
- Individuals being evaluated for nutrient deficiency
- Patients with unclear abnormalities in blood tests
- Anyone monitoring anemia treatment
How to Prepare for Your Test
No special preparation is required. Bring valid ID to your appointment.
Order Your Blood Test
Test your Red Cell (RDW) Blood Test levels with an accredited Swedish laboratory. Results within days, reviewed by Wellth.
Frequently Asked Questions
What does a high RDW with low MCV mean?
Can RDW be high without anemia?
Is RDW included in a standard blood test?
Reviewed by
Wellth Team
Wellth
Our content is written and reviewed by Wellth, and fact-checked against peer-reviewed research and current Swedish clinical guidelines.
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The information on this page is provided for informational purposes only and does not constitute professional medical advice, diagnosis, or treatment. Wellth provides health information and testing services but is not a substitute for clinical care. Always consult a qualified healthcare provider if you have questions about a medical condition. If you are experiencing severe or urgent symptoms, contact your doctor or call 1177 Vårdguiden. Blood test results should be interpreted by a qualified healthcare professional in the context of your complete medical history.