Receiving an abnormal blood test result can understandably cause concern. Red Cell Distribution Width-Coefficient of Variation, or RDW-CV, is a parameter in a standard blood panel related to your red blood cells. This article clarifies what a high RDW-CV signifies and provides context for its interpretation.
Understanding RDW-CV
RDW-CV stands for Red Cell Distribution Width – Coefficient of Variation. This measurement is a standard component of a complete blood count (CBC) and offers insights into the variability of red blood cell sizes within a blood sample. A normal range for RDW-CV is typically between 11.5% and 15.4%, though this can vary slightly by laboratory.
Red blood cells transport oxygen, and their efficiency is partly linked to their size and shape. While some natural variation exists, significant differences can indicate underlying health issues. The RDW-CV assesses this variation, a condition known as anisocytosis, providing a snapshot of red blood cell uniformity.
Interpreting a High RDW-CV
A high RDW-CV indicates a greater than normal variation in the size of red blood cells circulating in your bloodstream. This means a mix of smaller and larger cells, a condition formally termed anisocytosis.
This increased variation suggests the body is producing red blood cells of different sizes or that existing red blood cells are changing size. A high RDW-CV points to a wider spread around the average volume. An elevated RDW-CV is not a diagnosis itself, but an indicator that prompts further investigation into potential underlying conditions affecting red blood cell production or lifespan.
Common Causes of Elevated RDW-CV
An elevated RDW-CV can stem from various underlying health conditions that impact red blood cell production, lifespan, or integrity. One frequent cause is iron deficiency anemia, where insufficient iron stores lead to the production of smaller, varied-sized red blood cells as the bone marrow attempts to compensate.
Deficiencies in essential vitamins, particularly vitamin B12 and folate, are another common factor. These can result in macrocytic anemia, characterized by abnormally large red blood cells, contributing to increased size variation. When both iron and vitamin deficiencies are present, a mix of small and large cells can lead to a markedly elevated RDW-CV. Chronic diseases, such as kidney disease, liver disease, or inflammatory conditions, can also influence red blood cell production and lead to an elevated RDW-CV.
Acute or chronic blood loss can also cause a high RDW-CV as the body rapidly produces new red blood cells that may differ in size from existing cells. Less common causes include hemolytic anemia, where red blood cells are prematurely destroyed, and myelodysplastic syndromes, disorders affecting bone marrow blood cell production. Recent blood transfusions can also temporarily elevate RDW-CV due to donor cells having different size characteristics.
Next Steps After an Elevated Result
An elevated RDW-CV is one piece of information within a broader diagnostic assessment. Healthcare providers evaluate this finding with other complete blood count parameters, such as Mean Corpuscular Volume (MCV), Mean Corpuscular Hemoglobin (MCH), and hemoglobin levels. These results, combined with symptoms and medical history, help narrow down potential causes.
Further diagnostic tests may be recommended to pinpoint the reason for elevated RDW-CV. These can include iron studies, vitamin B12 and folate levels, or specific tests for chronic diseases. A peripheral blood smear may also be examined to visually assess red blood cell characteristics. Consult a healthcare professional for an accurate diagnosis and treatment plan. This article is for informational purposes only and does not provide medical advice.