# Red Cell Distribution Width (RDW) Analyzer

Analyze Red Cell Distribution Width (RDW) with MCV to help differentiate anemias. RDW-CV reference ≈ 11.5–14.5%, RDW-SD ≈ 39–46 fL (lab-dependent). Elevated RDW reflects anisocytosis. Classic Bessman patterns: high RDW + low MCV → iron deficiency anemia (IDA), which raises the RDW early — before MCV/Hb fall; normal RDW + low MCV → thalassemia trait (uniform microcytosis). Other patterns: high RDW + high MCV → megaloblastic anemia (B12/folate), MDS, drugs, hemolysis with reticulocytosis, preleukemia, or mixed populations (combined iron + B12 deficiency, post-transfusion); high RDW + normal MCV → early/mixed nutritional deficiency, dimorphic anemia, marrow recovery; normal RDW + normal MCV → anemia of chronic disease is classically normocytic. Interpret with Hb, ferritin, Hb electrophoresis, and clinical context. Based on Bessman 1983 and Teixeira 2014. Not medical advice.

> Canonical page: https://elysiatools.com/en/tools/rdw-analyzer

- **Category:** Health

- **Keywords:** rdw, red cell distribution width, anisocytosis, iron deficiency anemia, thalassemia trait, mcv, microcytosis, macrocytosis, megaloblastic anemia, bessman, hematology

## Overview

The Red Cell Distribution Width (RDW) Analyzer evaluates RDW-CV or RDW-SD together with MCV to identify common red-cell size patterns that may help differentiate anemias. Results use laboratory-dependent reference ranges and are not medical advice.

## Inputs

- **RDW Form** (select): RDW-CV (coefficient of variation, %) is most commonly reported; RDW-SD is the distribution width in fL.
- **RDW Value** (number): RDW value in the unit selected above (RDW-CV in %, RDW-SD in fL).
- **MCV (fL)** (number): Mean corpuscular volume in fL. Reference ~80–100 fL (lab-dependent).
- **Decimal Places** (number)

## When to use

- Compare RDW with MCV when reviewing a complete blood count for anemia patterns.
- Screen for patterns such as high RDW with low MCV or normal RDW with low MCV.
- Use as an initial interpretation aid before reviewing ferritin, Hb electrophoresis, hemoglobin, and clinical findings.

## How it works

- Select the RDW form: RDW-CV in percent or RDW-SD in fL.
- Enter the measured RDW value and MCV in fL.
- The analyzer compares RDW and MCV with approximate reference ranges and classifies the pattern.
- The result is returned as JSON with RDW status, MCV category, pattern category, and model information.

## Use cases

- Reviewing microcytic anemia patterns by combining RDW with MCV.
- Comparing possible iron deficiency and thalassemia-trait patterns.
- Organizing CBC findings before follow-up laboratory evaluation.

## Frequently asked questions

### What inputs does the RDW Analyzer require?

It requires an RDW form, an RDW value, and an MCV value in fL. Decimal places are optional.

### What is the difference between RDW-CV and RDW-SD?

RDW-CV is the coefficient of variation reported as a percentage. RDW-SD is the distribution width reported in fL.

### What does a high RDW with low MCV suggest?

It is a classic pattern of iron deficiency anemia, although other mixed or dimorphic processes are possible.

### What does a normal RDW with low MCV suggest?

It indicates relatively uniform microcytosis, a classic pattern associated with thalassemia trait.

### Is this analyzer a medical diagnosis?

No. Interpret the result with hemoglobin, ferritin, Hb electrophoresis, laboratory ranges, and clinical context.

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