RDW-CV, or Red Cell Distribution Width-Coefficient of Variation, is a measurement in routine blood tests. It provides insights into your red blood cells, which carry oxygen throughout your body.
What RDW-CV Represents
RDW-CV measures the variability in the size and volume of your red blood cells. Normally, red blood cells maintain a relatively uniform size to efficiently transport oxygen. However, certain conditions can lead to variations in their dimensions, a phenomenon known as anisocytosis.
This measurement is a component of a Complete Blood Count (CBC) analysis. A higher RDW-CV value indicates a greater degree of size variation among red blood cells, while a lower value suggests more uniform cell sizes.
Interpreting Your RDW-CV Results
The normal reference range for RDW-CV typically falls between 11.5% and 14.5% for adults, though slight variations can exist between different laboratories.
A high RDW-CV indicates that your red blood cells vary significantly in size. This increased variation, or anisocytosis, suggests that your body is producing or destroying red blood cells at different rates or in an abnormal manner. It can be an early sign of underlying issues, sometimes even before other red blood cell parameters change.
Conversely, a low RDW-CV typically signifies that your red blood cells are more uniform in size than usual. This finding is generally not considered clinically significant on its own and is often a normal result.
Health Conditions Linked to RDW-CV Variations
An elevated RDW-CV can be associated with various health conditions, particularly those affecting red blood cell production or lifespan. A common cause is iron deficiency anemia, where the body lacks sufficient iron to produce healthy red blood cells, leading to a mix of smaller and normal-sized cells. RDW-CV can be an early indicator in iron deficiency anemia. Deficiencies in vitamin B12 or folate can also cause an elevated RDW-CV, as these nutrients are crucial for proper red blood cell maturation, often resulting in larger red blood cells.
Thalassemia, a genetic blood disorder, can also affect RDW-CV. Beyond nutritional deficiencies and genetic disorders, an elevated RDW-CV can also be observed in conditions such as chronic inflammation, liver disease, and kidney disease. Cardiovascular diseases and some cancers have also been linked to higher RDW values. RDW-CV is a supportive diagnostic tool, providing a clue that further investigation may be needed rather than a definitive diagnosis.
What to Do If Your RDW-CV Is Abnormal
If your RDW-CV results fall outside the normal range, discuss these findings with a healthcare professional. An abnormal RDW-CV is one piece of the diagnostic puzzle and needs to be interpreted with other blood test results. Your doctor will consider other red blood cell indices from your Complete Blood Count, such as Mean Corpuscular Volume (MCV), Mean Corpuscular Hemoglobin (MCH), Mean Corpuscular Hemoglobin Concentration (MCHC), and your hemoglobin and hematocrit levels.
These additional parameters, along with your health history and any symptoms you may be experiencing, help your doctor understand the full picture. For example, a high RDW-CV combined with a low MCV might suggest iron deficiency, while a high RDW-CV with a high MCV could point to vitamin B12 or folate deficiency. Further diagnostic tests might be recommended, including specific iron studies, vitamin level assessments, or a bone marrow biopsy.