An RDW (Red cell Distribution Width) blood test measures the variation in size and volume of your red blood cells. It is a component of a Complete Blood Count (CBC).
Understanding RDW
- What it Measures: The RDW test specifically looks at how much the size of your red blood cells differs from one another. In a healthy person, red blood cells are generally similar in size. An RDW test reveals whether there's a large variety in sizes.
- Part of CBC: As indicated in our reference, the RDW test is usually performed as part of a complete blood count (CBC). A CBC provides a wide range of information about your blood cells.
- Why it's important: A high RDW value can be an indication of certain medical conditions.
How is it Used?
Here are some ways the RDW result is typically used:
- Diagnosing Anemia: An abnormal RDW, when paired with other tests like hemoglobin and hematocrit from the CBC, can aid in diagnosing different types of anemia.
- Identifying Nutritional Deficiencies: Variations in red blood cell size can be related to nutritional deficiencies, such as iron deficiency or Vitamin B12 deficiency.
- Monitoring Medical Conditions: The RDW test may be used to follow treatment progress in chronic medical conditions.
What Does a High RDW Mean?
A high RDW typically indicates that there is a greater variation in the size of your red blood cells than normal.
- Potential Causes: Some causes of high RDW are anemia, iron deficiency, vitamin B12 or folate deficiency, liver disease, or certain genetic blood disorders.
- Additional Testing: If the RDW test results are abnormal, a healthcare professional will often order further blood tests or investigations to identify the underlying cause.
RDW Test Results
Results are usually shown as a percentage. The normal range for RDW can vary slightly between laboratories.
- Low RDW: RDW values that are within the lower range of normal usually don't raise any medical concerns.
- High RDW: RDW values that are above the normal range need further review and investigation by a medical professional.
Summary
The RDW blood test is a simple but important part of a complete blood count. It gives your healthcare provider valuable information about the size of your red blood cells, which can help with diagnosing and managing a variety of health issues.
