Hemoglobin is a protein that carries…. Iron is a vital mineral in the body, central to transporting oxygen around the body in the hemoglobin. A shortage of iron can cause health problems…. What does it mean if your RDW is high? Medically reviewed by Daniel Murrell, M. What is the RDW blood test? Preparing for the RDW test. RDW test results.
Share on Pinterest A RDW blood test is often included in a complete blood count, which measures all blood components. Scientists identify new cause of vascular injury in type 2 diabetes.
Adolescent depression: Could school screening help? Related Coverage. What is microcytic anemia? Medically reviewed by Alana Biggers, M. All you need to know about thick blood. What is nutritional-deficiency anemia? Medically reviewed by Kevin Martinez, MD. MCH levels in blood tests: What do they mean? What to know about iron deficiency anemia. Inflammatory cytokines can hinder red blood cell production, and thereby increase RDW levels.
In addition, oxidative stress that often accompanies chronic inflammation can decrease the lifespan of red blood cells and further increase RDW values [ 6 , 7 ]. If a person has many blood transfusions, their RDW can increase due to the differences in blood cells between the donor and the recipient [ 12 , 31 ].
Bleeding in Injuries increase RDW [ 32 ]. Bleeding may not necessarily be visible, as is the case with gut bleeding [ 33 , 34 ]. Erythropoietin , a hormone produced by the kidneys, is needed for the production and maturation of red blood cells. Abnormal production of this hormone happens in kidney disease leading to increased RDW [ 1 ]. People with decreased kidney function have higher RDW levels [ 35 ]. In a study of over RDW is also affected by shift work. RDW is higher in people with sleep apnea [ 38 , 39 ].
Hereditary red blood cell disorders, such as sickle cell anemia, thalassemia, and spherocytosis can increase RDW [ 12 , 40 , 12 ]. In all of these disorders red blood cells become misshapen. However, thalassemia patients may also have normal RDW levels [ 40 , 12 , 41 ]. RDW is higher in various cancers, including gastric, liver, colon, and kidney cancer [ 42 , 43 , 44 , 45 ].
There are many factors in cancer that can interfere with red blood cell production, such as chronic inflammation and poor nutritional status. In cancer, RDW often increases with disease severity and metastasis [ 46 ]. Metabolic syndrome is a group of health issues that together increase the risk of heart attack, stroke, and diabetes.
These issues are:. Similarly, another smaller study with 3. In another study of people with high blood pressure, higher RDW was associated with an increased risk of plaque buildup in the arteries atherosclerosis [ 50 ]. In a study that monitored 2. However, no link between RDW and cancer was found in premenopausal women [ 52 ]. In a study of over 8k adults and a year follow up, higher initial RDW values were associated with a higher risk of death.
In another study of over 51k people who were hospitalized due to critical illness and followed over one year, a higher initial RDW measurement was associated with higher all-cause mortality [ 54 ]. Finally, a meta-analysis looked at 13 trials with over 10k people who experienced acute coronary syndrome, which is decreased blood flow to the heart such that part of the heart muscle is unable to function properly or dies.
A low RDW during the syndrome was associated with a significantly lower heart disease and all-cause mortality and a lower risk of subsequent risk of having a major adverse cardiovascular event such as heart disease or stroke [ 55 ].
The additional lifestyle changes listed below are other things you may want to discuss with your doctor. Normal red blood cells average between 6 and 8 micrometers in diameter. RDW estimates the variation in sizes of the cells and is given as a percentage. The normal range for RDW is roughly Examples of anemias in which RDW is most often normal include:.
A few types of anemia associated with an elevated RDW include:. Using the combination of RDW and MCV is very helpful in differentiating some types of anemia which would otherwise be difficult to tell apart.
For example, both iron deficiency anemia and thalassemia are usually associated with a low MCV microcytic anemias , but the two conditions are treated differently. Checking the RDW can help distinguish between these. Similarly, megaloblastic anemias such as vitamin B12 deficiency and folate deficiency and non-megaloblastic anemias such as anemia related to liver disease are both associated with a high MCV macrocytic anemias , but again are treated differently.
In this case, the megaloblastic anemias usually have a high RDW and non-megaloblastic a low RDW, helping to make the distinction. RDW can also be very helpful in mixed anemias. For example, a combination of iron deficiency microcytic anemia and folate deficiency anemia macrocytosis may have a normal MCV normocytic anemia , but the RDW will be very high.
It's important to note that there are exceptions to these general rules—for example, sometimes anemia of chronic disease is associated with a low MCV, and sometimes iron deficiency anemia will show a normal MCV. In addition to a CBC, other tests that may be done to help identify anemia include:. The RDW can be a very helpful number even if there is no evidence of anemia if the red blood cell count and hemoglobin levels are normal.
The RDW can predict the overall risk of mortality in people over the age of 45 people with a high RDW are more likely to die earlier on than those who have a lower RDW. Many studies have been done in the last several years looking at the predictive value of RDW in a wide range of diseases.
Some of these include:. From another angle, researchers have looked at the potential for RDW to predict the risk of cancer in people who do not currently have the disease. For example, they found a dose-dependent relationship between high RDW values in men and postmenopausal women and future cancer risk. For people who are undergoing evaluation for unintentional weight loss , a high RDW increased the chance that the weight loss was due to cancer.
This area of research looking at the role of RDW in evaluating conditions other than blood conditions is quite new, and it's expected that more information will be available to better understand the potential benefits of looking at RDW in the future. Follow-up testing if the RDW is abnormal will depend on many factors. Red cell distribution width RDW is a valuable tool in evaluating the different types of anemia and may have a wide range of uses even when a person's red blood cell count is normal.
In addition to the conditions mentioned above, some argue that RDW could be a measure of general well-being. For now, it's uncertain the value this test will have in many conditions but it's noteworthy that simple tests such as these—that can easily be overlooked—may provide important information to be heeded.
In a blood test, the red cell distribution width RDW is the range of volume and size that blood cells can reach. It is used to help diagnose certain conditions like anemia, thalassemia , heart disease , diabetes , liver disease, colorectal cancer , and more. A high RDW has been associated with some types of anemia, including iron deficiency anemia , vitamin B12 and folate deficiency, mixed anemias, sickle cell disease , myelofibrosis , and cold agglutinin disease.
It has also been linked to certain conditions unrelated to blood, such as sleep apnea and lupus. High RDW is not a guarantee these conditions are present.
Some people with anemia may bruise easily. Other symptoms of anemia can include dizziness, headache, heightened thirst, irritability, sore tongue, lower leg cramping during exercise, tiredness, pale skin, and weakness.
Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Reviewed July 31, Dugdale, A. Journal of Laboratory and Precision Medicine. McPherson R.
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