A complete blood count (CBC) is a test that shows the various contents of the blood, such as the blood cells, known as red blood cells, which carry oxygen to the rest of the body. One such measure in the CBC test is red cell distribution width (RDW), which is a measure of the variability of red cell size. The possible signals of nutritional deficiency and certain types of anaemia can be explained with the help of knowledge of the RDW in CBC findings.
What Is RDW in a CBC Blood Test?
The blood count RDW stands for red cell distribution width. It defines the intensity in the dimensions of the red blood cells that are also known as erythrocytes. When the size of these cells is widely distributed (and the RDW is high), then the RDW itself might be larger than what would be obtained in the reference range, given by the laboratory.
The terms what is RDW in CBC test and what is RDW blood count mean knowing this measurement in a blood report. RDW also helps the medical personnel to investigate possible causes of anaemia and interpret data of red blood cells and haemoglobin, and MCV and other parameters of the CBCs.
What Is the Normal RDW Range?
RDW normal range differs depending on the laboratory, analyser and reporting method. RDW-CV varies approximately between 11.5-14.5 per cent in adults, but it is only a rough guide. Always remember to refer to the reference interval on your report.
Understanding CBC Results
CBC results RDW and CBC test results RDW mean the amount of RDW reported in your blood count. An activity in the range of the reference values shows that the red blood cell size deviation is within the acceptable values of the laboratory. It on its own does not exclude anaemia or other health disorders.
What Does a High RDW Mean?
When RDW is high, red blood cells are not as homogeneous as they should be. This observation on a CBC report is called a high RDW. It can be a result of the body producing red blood cells of varying sizes due to nutritional deficiencies or other medical problems.
Common Causes of High RDW
Possible causes include iron deficiency, vitamin B12 deficiency, folate deficiency, blood loss and certain types of anaemia. The abbreviation CBC blood test RDW high signifies a high value, which needs to be interpreted with other scores.
RDW-CV high means to the fact that the coefficient of variation of the red cells size is increased. RDW-CV, the variability of cell volume in relation to the average cell volume, is computed. Even a good outcome does not determine the cause itself.
What Does a Low RDW Mean?
A low RDW typically implies that there is not much disparity in size in red blood cells. The finding is, in most cases, less clinically relevant as compared to an increased RDW, especially where other CBC results are normal.
A CBC blood test RDW low is a term used to depict a value that is lower than the laboratory reference range. Such a low RDW in itself does not typically imply a particular disease or need for treatment. Physicians take into account the complete blood count and symptoms prior to making a decision on the need to conduct further studies.
RDW and MCV: Why Are They Considered Together?
RDW and mean corpuscular volume (MCV) complement each other in their descriptions of the red blood cells. RDW is the measurement of variation in cell size, whereas MCV is their average size.
As an example, a high RDW/low MCV could be used to investigate iron deficiency, whereas low RDW/high MCV could be used to investigate vitamin B12 or folate deficiency. These are not diagnostic patterns, and there may be other causes.
What Can Affect RDW Results?
RDW can be affected by a variety of factors such as nutritional status, blood loss, underlying diseases and treatment history.
- Iron deficiency: Iron can influence the production of red blood cells due to low iron levels.
- Deficiency in vitamin B12 or folate: The deficiencies may result in production of abnormally large red blood cells.
- Recent blood loss: Newly formed cells may vary in size with the preexisting cells.
- Mixed nutritional deficiencies: Multiple deficiencies can lead to greater range of variation in cell size.
- Medical conditions: Some chronic diseases and blood disorders can impair red blood cell production.
RDW should therefore be assessed alongside haemoglobin, MCV and other relevant investigations.
When Should You Talk to a Doctor About RDW?
Talk to a health practitioner about abnormal RDW results, especially when haemoglobin and other CBC measurements are also out of their normal ranges.
A doctor can examine your medical history, diet, medications and symptoms and then prescribe further tests. The cause or underlying factor is used to treat them, not the number of each occasion (RDW).
