Blood tests provide insights into your overall health. Red Blood Cell Distribution Width (RDW-CV) is a parameter included in a complete blood count (CBC) that assesses the uniformity of your red blood cells.
Understanding Red Blood Cell Distribution Width
RDW-CV, or Red Blood Cell Distribution Width – Coefficient of Variation, measures the variation in the size of your red blood cells. While red blood cells typically have a consistent size for oxygen transport, some variation is natural. This test quantifies that variation. A higher RDW-CV value suggests greater variability in cell size, a condition known as anisocytosis.
The RDW-CV is reported as a percentage and is part of a standard CBC test. A typical normal range for adults usually falls between 11.5% and 14.5% or 15%, though these ranges can vary slightly by laboratory, age, and sex. This measurement helps evaluate the consistency of red blood cell volumes.
Interpreting a Low RDW-CV Value
A low RDW-CV indicates your red blood cells are very uniform in size, with less variation in their volume than typically observed. This means the red blood cells in your sample are consistently sized, appearing as a tightly clustered group on a size distribution graph. Unlike a high RDW, which often signals underlying conditions, a low RDW-CV is generally not considered clinically significant on its own.
Many healthy individuals have a low RDW-CV without associated health issues. This result is less common than an elevated RDW and rarely points to a specific disease in isolation. A low RDW-CV often means your body efficiently produces consistently sized red blood cells, which is typically a favorable outcome.
Clinical Significance of a Low RDW-CV
While a low RDW-CV is usually not a cause for concern, it can rarely be observed with other blood test results. For example, it might be seen in specific types of anemia where red blood cells are uniformly sized. These include certain microcytic anemias, where red blood cells are consistently smaller than normal, or macrocytic anemias, where they are consistently larger but still uniform.
In such cases, the low RDW is due to the consistent size of the cells, even if that size deviates from the average. Interpretations of a low RDW-CV are complex and require a healthcare professional’s assessment. They consider the result within the context of a full blood panel, particularly alongside the mean corpuscular volume (MCV), and the patient’s complete medical history.
What to Do After Receiving a Low RDW-CV Result
If you receive a low RDW-CV result, discuss it with your doctor. Blood test results are always interpreted in the context of your overall health, existing medical conditions, and other laboratory values. A low RDW-CV by itself typically signifies healthy uniformity in red blood cell size.
Your healthcare provider can offer the most accurate interpretation and guide you on any necessary next steps. They can determine if further investigation or additional tests are warranted based on your complete clinical picture.