What is RDW in Blood Test and What’s Normal Range?

Red blood cell distribution width (RDW or RDW-CV) is the measurement derived from red blood cell distribution width analyzed by hematology machines as a part of complete blood count, a laboratory test to identify some blood related disorders such as anemia. Red blood cell’s normal size is up to 6-8 μm in diameter and normal level is 10.2 to 14.5%. But of course, we must always consider the patient’s age being tested and the device used in determining its values. Acquiring some blood related disorder may cause a significant change in size and at the same time with its level. Some of these disorders are considered fatal, and so medical intervention must be given as fast prompt as possible.

What does RDW Mean in a Blood Test?

RDW result in a blood test will show the exact amount of red blood cells that indicates the disparity in size or volume of erythrocytes present in the blood sample.

There are different electronic devices that can be used in measuring RDW, and with that we must always consider some differences with the result. Also, other laboratory test used different unit in determining RDW, so it should also be take into consideration.

Measuring the “width” in RDW can sometimes be confusing since we are measuring the deviation of the volume of RBCs, and not directly the diameter. Nevertheless, “width” refers to the width of the volume curve (distribution width, here presented as the Coefficient of Variation, or CV), not the width of the cells.

RDW-CV (in percentage) = 1 SD of RBC volume/MCV x 100% (3,4)

Indication of RDW Result

RDW is basically measured through laboratory devices with the specimen derive from the specific person’s blood. Here are some of the indications of having abnormalities in RDW:

  • Normal RDW and Low MCV

Having this result in your blood test will suggest that you are suffering from anemia caused by chronic diseases, heterozygous thalassemia, or hemoglobin E trait. This also has something to do with genetics. A person may have this disorder mainly because of the genes inherited from primogenitor.

  • High RDW and Low MCV

This result will indicate two types of blood disorder, Sickle cell anemia and iron deficiencies. In order to be certain, further blood test is performed. This disorder needs urgent medical intervention since it’s the hemoglobin that carries oxygenated blood in our body. Having low amount of hemoglobin means that there is low amount of oxygenated blood in our body.

Another cause for this disorder is due to thalessemia intermedia. This blood disorder occurs when there is hobble in the production of hemoglobin.

  • Normal RDW and High MCV

This combination will catch your attention more for this will suggest aplastic anemia or chronic liver disease. These two conditions are considered fatal if diagnosed late. Aplastic anemia is a rare disease that involves bone marrow and hematopoietic stem cells. This will result to stem cells unable to generate mature blood cells. Chronic liver disease on the other hand is also a serious condition. This disease will process a progressive destruction and regeneration of our liver. Thus, considered a lethal disorder. But the use of antivirals, chemotherapy treatment and intake of alcohol will catalyze to have this result.

  • High RDW and MCV

If both RDW and MCV were elevated, it suggests that the liver takes part in deriving this type of abnormal blood result. It is the liver that filters blood in human body. If the liver won’t function as what it should be, toxins will now remain on the organ and later on spread all throughout the human’s system.

This will lead to a serious condition that could result to death.

  • RDW Level is High and the MCV is Normal

Having this result will indicate vitamin B12 or foliate deficiency. Deficiency with these two nutrients will disturb the production of RNA, DNA and red blood cells. Also, this deficiency will result to extreme tiredness, muscle weakness, disturbed vision and some psychological effect like depression, confusion, problems with memory and judgment.

  • Both Normal RDW and MCV

This results states normal, but that doesn’t mean that everything is okay. Deriving with this result suggests that the person is suffering from anemia of chronic disease, anemia of renal disease or hemolysis which means that the red blood cells are rupturing.

Reference: Act for Libraries