What is rdw in blood test

What is RDW?

RDW stands for Red Cell Distribution Width, a measurement included in a complete blood count (CBC) test. It quantifies the variation in size of your red blood cells and is expressed as a percentage. Unlike other blood tests that measure absolute values, RDW measures the degree of variation or heterogeneity in red blood cell dimensions.

Understanding Normal Ranges

Most laboratories report normal RDW values between 11% and 15%. However, the exact reference range can vary slightly depending on the laboratory and the specific testing equipment used. Your healthcare provider will interpret your results based on the specific range provided by the laboratory that performed your test.

What High RDW Indicates

When RDW is elevated (higher than normal), it suggests that your red blood cells vary significantly in size. This condition, called anisocytosis, can indicate several underlying health issues:

• Iron deficiency anemia, one of the most common causes of high RDW
• Vitamin B12 deficiency or pernicious anemia
• Folate deficiency
• Chronic liver disease or alcoholism
• Hemolytic anemia or other blood cell disorders

RDW and Anemia Diagnosis

RDW is particularly useful for diagnosing different types of anemia. When combined with the Mean Corpuscular Volume (MCV), which measures average red blood cell size, RDW helps distinguish between various anemic conditions. For example, iron deficiency anemia typically shows both low hemoglobin and high RDW, while other conditions may show different patterns.

Interpreting Your Results

If your RDW is abnormal, your doctor will typically order additional tests to determine the underlying cause. These may include serum iron, ferritin, vitamin B12, and folate levels. It's important not to self-diagnose based on RDW alone, as it requires interpretation in context with other blood values and clinical symptoms.