What is B-RDW?
B-RDW (Red cell distribution width) is a marker used to measure the size variation of red blood cells (erythrocytes). It is an important biomarker in the investigation of anemia and can provide information about abnormalities in blood formation. By analyzing the size distribution of erythrocytes, conditions in which red blood cells exhibit increased size variation, also known as anisocytosis, can be identified.
Why analyze B-RDW?
B-RDW is used to assess variations in the size of erythrocytes and can, together with other erythrocyte indices, such as B-MCV, Erc(B)-MCH, and
B-RDW is calculated as a coefficient of variation (CV%) and the formula for calculation is:
B-RDW-CV = (Standard deviation of erythrocyte volume x 100) / Mean cell volume (MCV)
What can a high B-RDW value indicate?
An elevated B-RDW indicates a greater variation in the size of the erythrocytes and can be associated with several conditions:
- Iron deficiency anemia: Usually accompanied by a low MCV.
- Hemolytic anemia: Due to increased production of different sizes of erythrocytes.
- Post-bleeding: Where newly formed erythrocytes have a larger volume than older cells.
- B12 or folate deficiency: Often with a high MCV and an increased proportion of immature erythrocytes.
- Myelodysplastic syndrome: A hematological disease in which erythropoiesis is disturbed, which is done in uneven size of the erythrocytes.
What can a low B-RDW value indicate?
A low B-RDW value is rarely clinically significant but can be seen in very homogeneous population groups, for example in certain chronic diseases where the erythrocytes have a consistent size.
How is B-RDW used to classify anemia?
The combination of and B-RDW can provide guidance in the classification of anemia:
- Microcytic anemia (MCV low):
- RDW normal: Thalassemia
- RDW high: Iron deficiency anemia
- Normocytic anemia (MCV normal):
- RDW normal: Secondary anemia in chronic disease
- RDW high: Early iron deficiency anemia, hemolysis, bleeding
- Macrocytic anemia (MCV high):
- RDW normal: Liver disease, alcohol abuse
- RDW high: B12/Folate deficiency, myelodysplastic syndrome
B-RDW is particularly valuable in unclear cases of anemia and in the investigation of disorders of erythropoiesis, even when hemoglobin levels are normal.
