The condition of the red blood cells is often an indicator of the health of an individual. A test that is sometimes done helps measure the red blood cell distribution width (RDW); This can determine how much the cells in a sample vary in size. However, the measurement does not generally represent the physical diameter. It usually represents the width of a graphical curve that shows how the volume of cells varies. A normal range is generally between 11% and 15% in the human body.
The distribution width of red blood cells is usually determined mathematically; the formula typically includes the mean corpuscular volume, or the average amount of space each cell occupies. The mathematical principle of standard deviation is applied to the value and is divided by the average volume. A result is multiplied by 100 to determine the RDW. Medical laboratories often have instruments that can pick up the pulses produced by red blood cells; The strongest pulses are usually produced by larger cells, while the weakest pulses are usually produced by smaller cells.
Laboratory reports often indicate the normal range for red blood cell distribution width. However, the ranges may vary depending on the type of equipment used for the measurement. If the RDW is high in a blood test, it usually means that the cells vary quite a bit in size; Anemia caused by an iron deficiency is sometimes a cause. Low levels of vitamin B12 or folic acid often lower the count as well. The carbon in vitamins, which the body needs, may be missing for normal function to take place.
If the width of the red blood cell distribution is high, it can also indicate a blood disorder in which the production of hemoglobin, which carries oxygen, is affected. Other conditions can cause red blood cells to break into fragments, which usually increases the RDW value. Low RBC distribution width, on the other hand, is also often an indicator of problems. One type of anemia can lower the count if there are an abnormally low number of cells, but they are relatively large. Deficiencies of certain vitamins can also be the reason for a low RDW percentage.
The distribution width of red blood cells can be correlated with the results of other health conditions. High variability in blood cell size often results in a less optimistic prognosis for people with heart failure, according to studies. The count may represent insufficient production of new cells, as well as more frequent cell destruction than normal, complicating underlying medical conditions.