When a doctor requires a platelet count, then a complete blood count may be ordered. The CBC blood test will include a measurement of platelet distribution width, which is how the PDW blood test results will be measured. The PDW is a reflection of how uniform in size a patient’s platelets happen to be. This can help to determine how effectively a person’s bone marrow is functioning and if follow-up tests may be required.
For platelet width, the general rule is that larger platelets are generally younger, while smaller platelets have been around for a few days. Having a high number of large platelets when someone has typically has a low platelet count indicates the bone marrow has stepped up production levels.
When Is the PDW Blood Test Ordered?
Because the PDW is part of a complete blood count, it may be ordered for a wide variety of reasons. The most common issues that doctors will examine are unexplained bruising, bleeding that continues on from small cuts or wounds, numerous nosebleeds, or internal bleeding in the digestive tract. The presence of a continuous rash or purplish spots on the skin may also cause this test to be ordered.
For women, when there is continuous and heavy menstrual bleeding, the PDW blood test may be ordered as well.
What Do My Results Mean?
The PDW blood test will generally be communicated with results that are low, normal, or high. Here is what those results mean.
This is an indication that the platelet width varies dramatically. There are numerous younger platelets and numerous older platelets in the same sample. This may be an indication that some sort of disorder has affected the bone marrow or the platelets and further testing may be required. Certain cancers, anemia, and inflammatory conditions typically cause this result, as will some infectious diseases or the use of birth control pills.
This is an indication that the platelet widths are relatively the same in size. This is the test result that the average person is going to receive when a complete blood count is ordered.
This may also be an indication that there is a disorder present which is affecting the bone marrow and how it is able to produce platelets. Viral infections will typically produce this result, such as measles, hepatitis, or mononucleosis. Certain drugs and cancers can also cause this result.
Sometimes the PDW blood test results might come back and note that a patient has “giant” or “abnormally large” platelets. This test result may indicated that there is an immune disorder present or that there is a rare inherited disorder like Bernard-Soulier disease which is affecting the individual.
In rare circumstances, the PDW blood test may come back as being “incomplete” or “inconclusive.” This happens when there is clumping of the platelets that occurs during the complete blood count. A second test may be ordered in this circumstance with an anticoagulant added to prevent clumping so that the sample can be properly studied.
Sometimes a serious condition can occur where PDW results are temporarily high and may provide no signs or symptoms of a disorder. There are rare genetic conditions that may cause this and further testing will typically happen.
What Happens When the PDW Blood Test is Abnormal?
If the PDW blood test has abnormal results and if there isn’t a known cause for them, then a doctor may choose to perform additional follow-up tests in an attempt to confirm a diagnosis. This may include testing to find inflammatory conditions, the presence of infectious diseases, kidney failure, or bleeding disorders. Liver disease and iron studies may also be ordered, as will vitamin levels.
In severe instances of abnormality when there is not a definitive cause that can be determined, then a bone marrow biopsy may be ordered.
For patients who live in high altitude area, PDW test results may be affected by an individual’s living habits. Be sure to speak with a doctor about this issue if you have recently spent a at least 30 days in a high altitude climate.
The PDW blood test is generally used as a screening tool to see if a patient is experiencing good health. It is typically ordered as part of a routine health screening. If bone marrow disorders are suspected, however, it may also be ordered. Consider these results, compare them to your own results, and then be sure to speak with your doctor about what this may indicate for you and your unique health history.