It is a part of a complete blood count, which also measures your hemoglobin , hematocrit , and red and white blood cell counts [ 2 , 3 ]. Low values mean that your red blood cells are roughly similar in size, which is normal and desirable. Higher values mean that your red blood cells are produced in different sizes. In other words, there is some issue with red blood cell production or survival [ 2 , 3 , 4 ].
RDW normally ranges from The range may slightly vary between laboratories. Your doctor will interpret your results in conjunction with your medical history and other test results. A low value indicates that your red blood cells are uniform in size.
This is desirable and not a cause for concern [ 3 ]. However, it is still possible to have a blood-related disease and low RDW levels [ 3 ]. A high RDW means that your red blood cells are unequal in size. This condition is called anisocytosis [ 2 , 3 ]. Causes listed below are commonly associated with high RDW.
If your RDW is high, work with your doctor or another health care professional to get an accurate diagnosis. This happens because all of these nutrients are needed to produce healthy red blood cells. Any of these deficiencies can eventually lead to anemia. Alcoholics can have a high RDW without having liver disease. This is because alcohol can have toxic effects on red blood cells [ 13 ]. RDW is increased in various liver diseases, including hepatitis, alcoholic liver cirrhosis, biliary cirrhosis, and liver cancer [ 14 , 15 , 16 ].
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 your clinic has a lab associated with it, most often you will receive your results shortly after they are completed. In some cases, the blood sample will be sent out to a lab and your healthcare provider will call with results when they are available.
When you receive your results, it's helpful to ask for the exact numbers, including that of your RDW. Reference ranges for RDW can vary somewhat by the laboratory doing the test. 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. Patients older than 18 who were diagnosed with malignant tumors were included.
The primary outcome was cancer mortality in hospital. Logistic regression and multivariate analysis were used to assess the association between the RDW and hospital mortality.
A total of eligible patients were enrolled. A positive correlation was observed between RDW and overall cancer mortality. Patients with higher RDW Similar trends were also observed in the model adjusted for other clinical characteristics. This suggested that elevated RDW was related to increased risk of cancer mortality, and RDW may play an important role in the prediction of short-term mortality after hospitalization in cancer patients. Elevated RDW was associated with overall cancer mortality.
To a certain extent, RDW may predict the risk of mortality in patients with cancers; it was an independent prognostic indicator of short-term mortality after hospitalization in cancer patients.
Cancer imposes a serious disease burden worldwide, with high incidence and mortality [ 1 ]. The top 10 tumors were cancers of the lung, esophagus, liver, cervix, stomach, breast, colon-rectum, lymphocytes, nasopharynx, and ovary. Five-year survival rates for all-combined cancer were only The primary methods of cancer treatment are surgical treatment, chemotherapy, and radiotherapy; however, even with all these advances, a large number of patients still have poor prognosis [ 4 — 6 ].
Considering the high incidence of cancer and its poor prognosis, it would be of great significance to find effective clinical predictors of mortality in cancer. Recently, several studies have reported that red blood cell distribution width RDW was associated with mortality in various cancers; however, there was substantially less evidence regarding RDW and all-combined cancer [ 7 — 10 ].
Many factors that could affect long-term prognosis of cancers have been identified, but there are relatively few identified factors affecting short-term prognosis. The red blood cell distribution width RDW is a parameter that reflects the degree of heterogeneity of erythrocyte volume; it is traditionally used in hematology laboratories to help classify the anemia [ 7 ].
Nonetheless, recent evidence has shown that RDW was associated with human diseases, including cardiovascular diseases [ 8 , 9 ], venous thromboses [ 10 ], liver diseases, and kidney failures [ 11 , 12 ], as well as with various cancers [ 13 ].
Several studies have reported that RDW predicted the mortality of various cancers, including cancers of the lung [ 14 , 15 ], stomach, colon, and endometrium [ 16 — 18 ]. Thus, there is a close relationship between RDW and cancer mortality.
However, evidence of the role of RDW in all-combined cancer remains scarce, and the short-term prognostic value of RDW in terms of mortality remains unclear. Therefore, studying the relationship between RDW and cancer mortality is of great significance for both clinical diagnosis and patient short-term prognosis.
To protect privacy, all patients were deidentified. A total of admissions were recorded. The data extracted were patient identifiers, demographic parameters, clinical parameters, and laboratory parameters.
Patient identifiers and demographic parameters included age, gender, and ethnicity. We extracted the following clinical parameters: systolic blood pressure SBP ; diastolic blood pressure DBP ; heart rate; respiratory rate; and comorbidities including atrial fibrillation AF ; congestive heart failure CHF ; renal and liver diseases; valvular disease; and stroke and pneumonia.
Laboratory parameters extracted included the following: body mass index BMI ; white blood cell count WBC ; platelet count; hematocrit; hemoglobin; blood urea nitrogen BUN ; serum anion gap; bicarbonate; creatinine; and glucose. A sequential organ failure assessment SOFA score was also calculated to assess the severity of illness. Hospital mortality was the primary outcome.
Categorical variables were presented as percentage and variances were analyzed by the Chi-square test. In order to determine whether the RDW was independently associated with cancer mortality, two multivariable analysis models were established on the basis of RDW groups.
In model I, we adjusted only for age and gender. In model II, we adjusted for age and gender, as well as for SBP, DBP, BUN, hemoglobin, serum sodium, potassium, platelet, hematocrit, anion gap, renal disease, liver disease, stroke, heart rate, pneumonia, and respiratory rate.
Meanwhile, we performed subgroup analysis to determine whether the effects of RDW varied between various subgroups. Our statistical analyses were performed on Empowerstats version 2. A total of eligible cancer patients were enrolled. According to RDW value, patients were divided into three groups low, mid, and high. Selected characteristics and laboratory data in the RDW groups are displayed in Table 1.
Characteristics such as gender and body mass index BMI showed little difference among groups. Patients in the higher RDW group more likely have higher blood pressure, heart rate, and respiratory rate. Patients with higher RDW had more comorbidities, including atrial fibrillation AF , congestive heart failure CHF , valvular disease, renal and liver disease, stroke, and pneumonia. However, platelet count, hematocrit, hemoglobin, serum bicarbonate, and glucose were lower in patients with higher RDW than patients in other groups.
We considered RDW as a continuous variable. Figure 1 shows the association between RDW and cancer mortality. A positive correlation was observed, suggesting that patients with higher RDW were at greater risk of cancer mortality.
Meanwhile, RDW was also independently associated with cancer mortality when adjusted for age, gender, BUN, hemoglobin, sodium, potassium, platelet, hematocrit, anion gap, renal disease, liver disease, stroke, heart rate, pneumonia, SBP, DBP, and respiratory rate Figure 2 , Table 2. The relationship between RDW and the cancer mortality was similar in most strata Table 3. Patients in most subgroups had no differences in terms of risk of cancer mortality according to RDW.
We also made a subgroup analysis of the types of tumor. The three different types of tumors were lung cancer, gastroenteric tumor, and breast cancer. The associations between RDW and the mortality of three different types of tumors were presented in Table 4. We found a positive correlation between RDW and cancer mortality, with higher RDW associated with increased risk of cancer mortality, showed RDW may be used to predict the mortality of tumor and the risk assessment of tumor patients.
On multivariate analysis, the model only adjusting for age and gender suggested that higher RDW correlated with increased risk of hospital mortality. Be sure to talk to your doctor before taking any supplements or making any changes in your eating plan. The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.
What is a red cell distribution width test? What is it used for? The RDW test may also be used to diagnose: Other blood disorders such as thalassemia , an inherited disease that can cause severe anemia Medical conditions such as heart disease , diabetes , liver disease , and cancer , especially colorectal cancer. Why do I need an RDW test? What happens during an RDW test? Will I need to do anything to prepare for the test?
Are there any risks to the test? What do the results mean? This combination of results can provide a more complete picture of the health of your red blood cells and can help diagnose a variety of conditions, including: Iron deficiency Different types of anemia Thalassemia Sickle cell anemia Chronic liver disease Kidney disease Colorectal Cancer Most likely your doctor will need further tests to confirm a diagnosis.
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