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Dr. Shreya Gupta
BDS, MDS - Oral and Maxillofacial Pathology
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MBBS, MD (Pharmacology)
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Understanding RDW CV

What is RDW CV?

A RDW CV test measures the size variation in the red blood cells (RBCs). This test is a key indicator of conditions related to the variation in RBC size, such as anemia, nutritional deficiencies, or inflammatory conditions. It is often done as part of a complete blood count test that also measures other types of blood cells. 

RDW CV is calculated by dividing the standard deviation of the red blood cell size by mean corpuscular volume (MCV), which is the average size of the red blood cells multiplied by 100. This gives you the percentage that represents the variation in the size of your RBCs (RDW-CV).

Normally, all RBCs are of the same size but sometimes they may vary. A high RDW means that there is a greater variation in the size of the RBCs, which can be a sign of an underlying health condition, such as anemia. On the other hand, a low RDW CV means there is little variation in the size of the RBCs and is generally not a concern but may help in ruling out certain health conditions, such as thalassemia, hemoglobinopathies, chronic liver disease, etc. 

A RDW CV test helps assess the range of RBC sizes in the blood. It is often grouped with other tests to help provide information about the features and qualities of red blood cells. No special preparation is required for this test. You can eat or drink as per your daily routine while taking this test. 

Test result ranges are approximate and may differ slightly between different labs depending on the methodology and laboratory guidelines. Talk to your doctor about your specific test results. The results will help them determine your medical condition and formulate an overall treatment plan.

What is RDW CV used for?

A RDW CV test can be done:

  • As part of a complete blood count test to monitor your overall health.

  • When you have symptoms suggestive of anemia, such as fatigue, dizziness, cold feet or hands, or pale skin. 

  • If you have a family history of sickle cell anemia, thalassemia, or any other genetic hematological condition.

  • When you are suffering from long-term illnesses or infections, such as diabetes, HIV/AIDS, or Crohn’s disease.

  • If you have excessive blood loss due to a medical procedure or injury.

  • When you are on a diet that is low in minerals and iron.

What does RDW CV measure?

An RDW CV test which is part of red cell indices, helps identify characteristics of red blood cells. RDW (red cell distribution width) measures the variations in the sizes of red blood cells, indicating how much they differ from each other in a blood sample. RDW is expressed as RDW-CV, a coefficient of variation. A higher RDW may suggest more variation in red cell sizes, while a lower RDW indicates more uniform red cell sizes.


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