A Red-cell Distribution Width test, more commonly referred to, as an RDW test, can be described as a blood test, which calculates the variations in the size of the red blood corpuscle. In most cases, the red blood corpuscles are uniform in size. However, with age, the cells tend to get smaller, due to which all of them do not remain at the same size. Other conditions which could lead to a change in the size of the RBC include pernicious anemia. At times, it is not just the size that changes, but also the shape. In order to detect if there are any changes in the size or the shape of the red cells, a patient may be required to undergo an RDW test. Hence, in case a medical health care provider suspects that a patient may be suffering from iron deficiency or anemia then an RDW test could be recommended. In fact, the RDW test is generally performed as a regular part of a Complete Blood Count (CBC)
In most cases, normal RDW test results show a range of 11% to 15%. In case of a RDW test high reading, it is absolutely essential for people to speak to their doctors and undergo the appropriate treatment. Moreover, in most cases, the RDW testing procedure is followed by a MCV blood test, to check what the exact cause of the problem could be.
An RDW test includes MCH blood test, that is, a test where a sample of blood is obtained. Hence, in this procedure, a needle is inserted, into a vein of the arm. In most cases, the vein from the arm, i.e., the inside of the elbow is used. For some people, a different site may be more suitable, like the back of the hand. In case a child or an infant is required to take the RDW test, the tip of the finger or the skin on the heel may be pierced. The blood that is drawn is collected into a glass vial or a glass tube (pipette). Though the procedure may cause a small amount of discomfort, it hardly ever leads to physical pain or distress. However, after a while there may be a little bit of tenderness felt and perhaps even bruising on the site. In order to minimize any after effects, like bruising or bleeding, gentle pressure may be applied to the site.
It is essential to get the RDW test performed by a doctor; the results of this test too, need to be analyzed by a medical health care provider.