RDW Blood Test: Meaning, Normal Range, High & Low Levels, and Causes
Time to read 6 min
Time to read 6 min
Table of contents
The RDW blood test assesses the size of red blood cells and how equal they are. It is a part of the complete blood count (CBC) and is measured in percentage. The normal RDW range is 12-15 % however, the reference range may slightly vary depending on the laboratory. Typically, the standard size (diameter)of red blood cells ranges between 6-8 micrometers.
The RDW blood test measures the difference in the size and volume of your red blood cells. Healthcare professionals use the RDW test to get a better picture of your circulatory system and to diagnose certain diseases. High RDW indicates greater variation in red blood cell size, called anisocytosis, and it can be a sign of iron deficiency anemia or nutrient deficiency.
In this article, we will talk about the RDW Blood Test, normal range, causes, high and low levels, and all you need to know about this test.
RDW means Red Cell Distribution Width, which measures the variation in the size of red blood cells. The sizes of red blood cells are associated with various health issues; thus, these variations offer insight into the underlying health conditions.
Red blood cells are formed in the bone marrow, and their prime role is to transport oxygen from the lungs to the tissues across your body. Cells use oxygen to grow, multiply, and produce energy. Typically, all red blood cells are of the same size; however, significant variations in size may influence how well they perform their job.
RDW-CV means Red Cell Distribution Width Coefficient of variation is a blood test that is performed to detect the size variation in your red blood cells. RDW-CV blood test calculation is derived from the standard deviation of red blood cell volume and the mean corpuscular volume. If an RDW-CV value is high, it indicates a higher range of variation in the sizes of red blood cells, suggesting a potential health concern.
RDW-SD, meaning in the blood test, is Red Cell Distribution Width Standard deviation, which measures the size variation in red blood cells. RDW-SD specifically measures the width of the distribution curve of the red blood cell volumes, which is mentioned in femtoliters or fL. RDW-SD in the blood test is a part of the usual Complete Blood Count. A high RDW-SD value means a broader range of RBC sizes that can be associated with many health conditions, such as anemia.
Typically RDW normal value ranges between 11% to 14.5%. The Red Blood Cell Distribution Width normal range shows uniformity in red blood cell sizes.
Sometimes, if your CBC test results show a normal RDW test value, you may still have anemia. In such a situation, your doctor or the healthcare professional considers other tests along with CBC test values to detect the type of anemia.
When the RDW shows normal results, the types of anemia that may be present are:
High levels of RDW indicate a significant variation in red blood cell sizes that is usually associated with chronic disease and other underlying health conditions. If your RDW test results indicate levels above the normal RDW levels, that means there is a problem, so you need to consult your healthcare provider for an accurate diagnosis.
Generally, the Low levels of RDW test are not problematic and suggest uniform red blood cell sizes. Typically, Lower values of RDW test results are not associated with any health condition.
Common Implications of low RDW
The Red Cell Distribution Width test results above 14.5% are considered high and necessitate further investigation. The severity of the underlying condition and potential dangers depend on the cause of high RDW levels and overall health condition. The clinical implications of high RDW levels are based on the other CBC parameters and the overall health condition of the individual. Make sure you discuss your RDW blood test results with your healthcare provider for an accurate diagnosis and proper treatment.
You may be asked to fast before an RDW blood test based on the other blood tests your healthcare professional has prescribed. The RDW test procedure requires just a few minutes; a medical professional will collect your blood sample from a vein through a needle. The blood sample is then sent to the laboratory for testing.
RDW means Red Cell Distribution Width, and MCV is Mean Corpuscular Volume, both are associated with Red Blood Cells. Both tests are red blood cell guides; RDW suggests the red blood cell size variation, while MCV suggests the average red blood cell size.
Diet may affect RDW if it causes deficiencies in vitamin B12, folate, or iron. A nutrient-rich diet can help sustain normal RDW, while nutrient deficiency may lead to high RDW.
Red Blood Cell Distribution width value can return to the normal value when the underlying cause is addressed and treated well.
A high red blood cell distribution width value is not always associated with anemia. High RDW may be a sign of anemia, but it may also be associated with other health problems.
The routine blood test, known as the Red Blood Cell Distribution Width blood test, is performed as a part of the Complete Blood Count test to check the overall blood health. It measures the variation in the size and volume of red blood cells. The RDW blood test can help diagnose various types of anemia and other health concerns associated with certain nutrient deficiencies. Along with the RDW blood test, healthcare professionals use other test results for proper diagnosis and treatment plan.
***Medical Disclaimer - The following information is for educational purposes only. No information provided on this website, including text, graphics, and images, is intended as a substitute for professional medical advice. Please consult with your doctor about specific medical advice about your condition(s).
