Friday, March 1, 2024

What Is Rdw In Blood Tests

Preparing For Rdw Test

Red Cell Distribution Width (RDW) What Does This Lab Test REALLY Mean?

A regular test will help you maintain the RDW blood test’s normal range. The RDW blood test may require fasting before the test. The doctor will inform you of all the instructions in advance.

The procedure for the blood test is simple and takes less than 5 minutes. The health care provider inserts a small needle into the vein, and the blood flows into a tube. After collecting the required blood in the tube, the needle is removed, and the patient is asked to hold a piece of gauze to stop bleeding. The individual may feel uneasiness for a short time and if the discomfort or the bleeding continues, visit the doctor without delay.

Then the blood sample is sent to the laboratory for further testing.

How Do I Interpret The Rdw Blood Test Reports

The RDW blood test reports generally take between 12-and 24 hours.

The RDW SD normal range is 12.2 to 16.1% and 11.8 to 14.5 in females and males.

Generally, the RDW blood tests high levels indicate possibilities of anemia, nutrient deficiency, or even an infection.

However, the RDW blood test reports independently cannot ascertain a diagnosis. Sometimes, even patients with normal range are later diagnosed with underlying disorders. For a more thorough diagnosis, your doctor will prescribe further testing, including mean corpuscular volume , etc.

What To Keep In Mind

  • A high RDW is associated with an increased in mortality rate as it causes a poor prognosis in some types of cardiac-related diseases.
  • RDW has a prognostic value in non-hematologic conditions.
  • RDW Blood Test has some limitations. If the level of RDW is checked after a blood transfusion, it wont lead to an accurate result. It usually leads to a false high result, especially if the lab uses EDTA anti-coagulated blood.
  • To calculate RDW, MCV should be first determined. So, an error in MCV calculation could lead to an error in RDW.
  • The reference range for RDW varies from one laboratory to another. The average value for RDW is around 11.8 to 15.6 percent. However, the number increases with age.


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What Is An Rdw Blood Test

An RDW blood test measures how varied your red blood cells are in size and volume. Your red blood cells carry oxygen from your lungs to organs and tissues throughout your body. The oxygen fuels your bodys cells so that they can produce energy.

When it comes to your red blood cells, size matters. Healthy red blood cells are about the same size, ranging from 6.2 to 8.2 micrometers. Having red blood cells that are vastly different sizes from each other may be a sign of anemia. Anemia is a condition that involves not having enough healthy red blood cells to supply oxygen to your bodys organs.

An RDW blood test is just one lab test your healthcare provider may use to diagnose anemia or other conditions.

What Does An Rdw Blood Test Measure

Elevated red blood cell distribution width (RDW) is associated with the ...

The word width in red cell distribution width can be confusing. Its easy to assume that the test measures the width of your red blood cells, but this isnt the case. Instead, an RDW blood test measures the variation in cell size among a representative sample of your red blood cells.

Cell distribution width refers to the distance between cell sizes as theyre plotted on a histogram. A histogram is a special type of graph that shows a range of numbers or values, like the range of red blood cell sizes. Similar values will be clustered close together on the histogram, and the RDW will be low. Different values will be spread out on the histogram, showing a wider distribution of values. In this case, the RDW will be high.

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Measurement Of Rdw And Laboratory Parameters

The blood samples were drawn from participating patients after an overnight fast of more than 12 h. The RDW, hemoglobin level, white blood cell count and mean corpuscular volume were determined using a Model S-PLUS JR Coulter Counter , with a Coulter histogram differential count as part of the complete blood cell count. The serum levels of total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and triglycerides were measured using a multichannel analyzer . Baseline RDW was measured as a continuous variable and the data were divided into four categories accordingly .

What Is The Rdw Blood Test

The RDW blood test checks the possibility of anemia by measuring the difference in size and shape of red blood cells. The human body requires oxygen to run normally. The RDW blood test normal range enables red blood cells to carry oxygen throughout the body. Whereas anything outside this range signals a possible health problem that may affect body function.

The standard size of red blood cells is 6 to 8 micrometers . The red blood cells are similar in normal conditions, although the high RDW blood test indicates the need for medical treatment.

The RDW test is often part of a Complete Blood Count test however, it is not the only parameter. In spite of this, it provides a higher meaning in the context of hemoglobin.

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Average Values Of Rdw And Mcv

We cannot talk about average RDW counts and values in blood tests without considering MCV. These acronyms correspond to the mean corpuscle value, and their analysis is closely linked to that of the RDW. Depending on the results of one and the other, it is influenced and can suggest different diagnoses. Various combinations can occur and can mean multiple pathologies:

  • Normal RDW and low MCV: May indicate chronic disease.
  • Low RDW and low MCV: Usually signify iron deficiency.
  • Normal RDW and normal MCV: It can be a chronic disorder.
  • High RDW and normal MCV: This may be due to a vitamin B12 deficiency.
  • Normal RDW and high MCV: Possibility of pre-leukemia.
  • High RDW and high MCV : This may be due to folate deficiency.

What Type Of Results Can You Get And What Do The Results Mean

How to Interpret RBC Indices (e.g. hemoglobin vs. hematocrit, MCV, RDW)

Test results appear as a percentage that lets you know whether your results are in the normal range or if your RDW is considered high or low.

Normal RDW

A normal result means that your red blood cells are similar in size. Generally, a normal RDW ranges from 12% to 15%, but this number may vary depending on the lab that performs the test. Your results report will highlight whats considered a normal range so that you can compare your numbers to whats typical.

A normal result doesnt mean that you dont have a condition requiring treatment. Some types of anemia involve a normal RDW result but a high or low score on one of the other RBC indices.

High RDW

A high RDW means that theres variation in the size of your red blood cells beyond whats considered normal. A high RDW may be a sign of anemia or a related condition. Your healthcare provider will need to look at other tests to be sure. Often, theyll look at the results of an RDW alongside the results of the MCV to assess the health of your red blood cells.


A low RDW isnt usually a cause for concern and isnt associated with any particular types of anemia.

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What Is Rdw In Blood Test And Normal Range

Most of the time we fear hearing highfaluting terms of abbreviation that are medical in nature. Lets take for example Red Blood Cell Distribution Width or simply known as RDW. The addition of the term width at the end means it is a measurement of what is being described. Therefore, it can be high, low or normal range. In addition, it is directly related to blood testing which would normally make us worrisome if not cringe at the thought of extracting it from our arm for testing. It is for volume and size of red blood cells which may differ person to person depending on age and condition.

RDW mean in a blood test can be very vague unless explained in laymans terms. It is composed of measurement and range as reference to determine a cause or presence of a disease in a person. This measures the size of red blood cells in different variants. We may also encounter MCV which means mean corpuscular volume when a doctor discusses a laboratory test.

Further Reading: MCH,MCHC

With the advancement of science and technology, there are available instruments that are highly capable of producing result and analyzing the sample of blood and detect pulses from red blood cells. It is calculated by dividing the total number of red blood cells over total number of it. In short, it means to measure red blood cell volume and size.

  • Normal RDW will show between 10.1% to 14.5% in a laboratory test result but would still depend on the apparatus used for the blood examination.
  • What Are Some Conditions Linked With High Rdw Levels

    Besides anemia, a high RDW level is indicative of several other underlying disorders, including:

    • Autoimmune diseases like lupus, rheumatoid arthritis, etc.
    • Congestive heart failure

    Sometimes, a few non-disease factors can also alter the average RDW test results. Blood transfusions are often a prevalent contributing factor.

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    What Is A Rdw Cv In Blood Test

    The RDW CV or corpuscular volume is the measurement in size and volume variations of the red blood cells. When you have the RDW blood test, the doctor will check if your red blood cells are within the normal range. or the results of the RDW normal range. This means that the result produces is what determines your range. RDW-CV blood test usually is a supplementary test in the RDW in the CBC blood test.

    Mostly, your doctor may request an RDW blood test under suspicion of the following situations

    • Any blood disorder

    Normal Reference Range For Rdw Blood Test


    Normal RDW values are between 11 and 14 percent, with an optimum RDW value range of 13 percent. When RDW values rise above normal levels, several disorders become suspect. According to the Archives of Internal Medicine, RDW counts may also play an important role in predicting mortality, especially in patients who have cardiovascular disease and cancer. In fact, patients who test higher than the normal reference range on an RDW test may suffer more health risks than those patients whose RDW values are lower.

    • Normal RDW values are between 11 and 14 percent, with an optimum RDW value range of 13 percent.
    • In fact, patients who test higher than the normal reference range on an RDW test may suffer more health risks than those patients whose RDW values are lower.

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    What Is Red Cell Distribution Width Blood Test

    RDW lab test is usually part of a complete blood count and is used in conjunction with the MCV test results to tell about your health. Usually, a doctor will take the blood test if there are concerns that you have anemia.

    According to Dr. Choladda Vejabhuti Curry on Medscape, the RDW results themselves wont confirm or rule out any type of anemia. Doctors will also take into account other indices on the complete blood test results like MCV and MCHC levels .1

    What Is The Red Cell Distribution Width Test

    The red cell distribution width is a blood test that determines how much red blood cells fluctuate in volume and size. If the width or volume of red blood cells departs from the normal range, it may indicate a biological problem that could affect oxygen delivery throughout the body.

    Size counts when it comes to red blood cells. The size of healthy red blood cells is similar, ranging from 6.2 micrometers to 8.2 micrometers. Anemia can be detected by having red blood cells that have substantially different sizes from one another. Anemia is a disorder in which the organs are deprived of oxygen due to a lack of healthy red blood cells.

    An RDW test is used in conjunction with other tests to diagnose and pinpoint the causes of anemia. This test is part of a complete blood count , which is a standard test used to diagnose and monitor a wide range of health problems. RDW is coupled with a panel of tests known as the red blood cell indices in a CBC report, which offer information on various characteristics and quality of red blood cells.

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    Measuring Red Blood Cell Distribution Width

    There are different ways to measure the distribution width of red blood cells. One is the use of an electronic supplement that can analyze the sample of blood and detect pulses produced by red blood cells. If the pulse is strong, the red blood cell size is huge. However, if the pulse is weak, it indicates that the red blood cells are small.

    Hematology analyzer is used to measure the size of red blood cells and to calculate the red blood cell distribution width according to the coefficient of variation in, and the red blood cell populations standard deviation.

    The formula to calculate RDW-CV is RDW-CV=1SD x 100/MCV.

    Another method of finding out red blood cell distribution width is by taking a look at the standard deviation of the red blood cell distribution, which is the actual measurement of the width of the red blood cell distribution curve.

    It is the perfect method in reflecting red cell anisocytosis because it is directly measured and has nothing to do with MVC.

    What Does It Mean When Rdw Is High On Blood Test

    Complete Blood Count (CBC) Test Results Interpretation w/ Differential Nursing NCLEX

    High results If your RDW is too high, it could be an indication of a nutrient deficiency, such as a deficiency of iron, folate, or vitamin B-12. These results could also indicate macrocytic anemia, when your body doesn’t produce enough normal red blood cells, and the cells it does produce are larger than normal.

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    Is Measuring Rdw A Must

    In routine blood check-up such as CBC/Complete Blood Count, the doctor might include RDW in testing patients that exhibit signs and symptoms of anemia such as weakness, headache, fatigue, pale skin, and cold and clammy hands/feet.

    The measurement of RDW is also emphasized if the patient has a family history of blood disorders such as sickle cell anemia and thalassemia. It is also one of the parameters to look at in patients with chronic medical conditions like Chrons disease, diabetes and HIV/AIDS.

    Obtaining RDW measurement is not that difficult. The lab technician will draw a blood sample and the sample is sent to the laboratory for thorough analysis. It is a quick procedure and usually does not require any special preparations and downtime.

    There might be some special instructions if a battery of tests has to be performed such as in the case of a patient with complex medical issues.

    Low Blood Rdw Or Anisocytosis

    If you have low blood RDW, a condition known medically as anisocytosis, you should know that it has no clinical significance, so you should not worry. RDW is only significant when it is high when it serves to differentiate different types of anemia.

    You have to be clear about what the RDW means to understand this. The RDW tells us about the differences between the size of red blood cells, so the smaller its value is, the more similar the size of the red blood cells is to each other. That is why a low RDW is not bad we might even see it as a positive.

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    What Does Rdw Blood Test Mean

    Red blood cells are part of the cells responsible for transporting the air we breathe. Besides that, they have hemoglobin. Hemoglobin is the red pigment that allows the blood to assume its color. Together with the white blood cells, they form a vital component of the blood.

    The RDW blood test is a clinical procedure to measure the volume and size variations in the red blood cells. If there is a variance in size or volume from the usual clinical range, further examination needs to happen. Depending on the doctor, you may undergo a CBC blood test. The supplementary procedure gives a broader and more accurate report on the overall condition of the blood.

    How To Measure Rdw Count In Blood Test

    Decoding your Blood Report Part 1: Red Blood Cells

    Now that you know what RDW in a blood test is, you must be curious about its procedure. Patients hardly have to undertake any preparation for taking only the RDW test. However, they might need to fast if there are other tests along with the RDW test. The process includes drawing blood samples from the patients.

    The healthcare professionals then send the sample to their laboratories to analyse the RBC count. After collecting the details from the lab test, doctors divide the standard deviation of the mean corpuscular volume by the MCV and multiply the result by 100 /×100). It helps them to gain an understanding of the percentage value RBC size heterogeneity in the body.

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    How Do I Prepare For An Rdw Blood Test

    You don’t need to do anything special to prepare for an RDW blood test. Your healthcare provider may order additional tests that require special preparation, like fasting, on the same day your blood is collected. In that case, follow their instructions to be sure you arrive fully prepared for whatever diagnostic tests you need.

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