What does my RDW result mean?

For evidence-based information about RDW (Red Cell Distribution Width), visit this page.

Does the elevation indicate iron deficiency?

For evidence-based information about RDW (Red Cell Distribution Width), visit this page.

How does RDW help distinguish between anemia types?

For evidence-based information about RDW (Red Cell Distribution Width), visit this page.

What factors may be affecting my result?

For evidence-based information about RDW (Red Cell Distribution Width), visit this page.

How often should I be retested?

For evidence-based information about RDW (Red Cell Distribution Width), visit this page.

Home → Tests → RDW

RDW (Red Cell Distribution Width)

✅ Up to date🔬 Evidence: ModerateHematology

Diğer adları: RDW-CV, RDW test, Red cell distribution width

⚠️

Discuss your test results with your doctor. This page is for informational purposes only and does not provide a diagnosis.

⚡ Key Facts

• Measures the variation in red blood cell size (anisocytosis) • Normal: RDW-CV 11.5–14.5% • Helps distinguish iron deficiency (high RDW) from thalassemia trait (normal RDW) • Increasingly studied as a prognostic marker in various conditions

🧪 What Does This Test Measure?

RDW (red cell distribution width) measures the degree of variation in red blood cell sizes, helping distinguish iron deficiency anemia from thalassemia trait.

📋 Why Is It Ordered?

Ordered for anemia differential diagnosis, distinguishing iron deficiency from thalassemia, and monitoring nutritional deficiency treatment response.

🔧 Preparation

Part of the CBC. No special preparation is required.

📊 Reference Ranges

Normal: RDW-CV 11.5–14.5% Elevated: >14.5% (anisocytosis — red blood cell size variation) ⚠️ Reference ranges vary by laboratory.

⬆️ High Values

Elevated RDW may be associated with iron deficiency anemia, B12 or folate deficiency, hemolytic anemia, recent transfusion, or mixed nutritional deficiencies.

⬇️ Low Values

Low RDW is generally not clinically significant. It indicates homogeneous red blood cell sizes.

⚙️ What Can Affect Results?

Blood transfusion, post-iron treatment changes, sample storage time, cold agglutinins, and reticulocytosis may affect RDW results.

🔬 Evidence Summary

Moderate evidence: 1 guideline, 1 systematic review, and 3 reviews/observational studies.

✅ Key Takeaways

💡

What you learned: RDW quantifies red blood cell size variation. It is particularly useful for distinguishing iron deficiency from thalassemia trait.

⛔

RDW alone cannot diagnose anemia type. It should be interpreted alongside MCV, iron panel, and clinical context.

🔬 Sources Used on This Page

5 sources · Most recent publication: 2024

📋

Guideline

Expert society and guideline recommendations

source

📊

Systematic review / meta-analysis

Combined analysis of multiple studies

source

📖

Review

Comprehensive topic evaluation

sources

👁

Observational

Observational and cohort studies

source

Overall assessment: Evidence level for this topic is strong. This page is supported by 1 guideline, 1 systematic review/meta-analysis, 2 reviews, 1 observational study.

📝 Questions to Ask Your Doctor

Be prepared for your appointment. Add questions to your list.

Last reviewed: 4/2/2026

Next review: 7/2/2026

⚖️ Comparisons

MCV vs RDW→

🔗 Related Topics

🧪 MCV (ortalama eritrosit hacmi)🧪 Hemoglobin🧪 Hemogram (tam kan sayımı)🧪 Ferritin (demir depoları)

⚖️ This page does not replace medical advice. Make treatment decisions with your doctor.
Content is based on scientific studies indexed in PubMed and current clinical guidelines.