Personal
Professional
Research
Personal Professional Research Sign Up Login Pro Login
Research RDW-CV (Red Cell Distribution Width) in %
Complete Blood Count (CBC)

RDW-CV (Red Cell Distribution Width) in %

Blood
Optimal Result: 11.7 - 15.4 %.

The RDW value tells you whether enough of your red blood cells are of normal size and shape.

Why is this important?

The red blood cells are usually flat and lenticular (disc-shaped) with a diameter of around 7.5 µm (micrometer).

What’s the function of red blood cells?

The sole function of red blood cells is to transport oxygen to different parts of the body.

Let’s describe a few terms first:

Blood Vessels:

Blood vessels are anything that carries blood. There are three major types of blood vessels:

- arteries,

- veins, and

- capillaries.

Let’s take a closer look at arteries and veins:

Arteries are blood vessels responsible for carrying oxygen-rich blood away from the heart to the body. Veins are blood vessels that carry blood low in oxygen from the body back to the heart for re-oxygenation.

Capillaries:

Capillaries are tiny blood vessels connecting arteries to veins. These blood vessels carry oxygen and nutrients to individual cells throughout the body.

OK, back to the red blood cells and their distribution width:

Blood cells must squeeze through the body’s smallest blood vessels, the above described capillaries, to do their job, but capillaries often become narrower than the cells in their normal disc shape. Capillaries can be as small as 4 µm in diameter. So the cells must deform and “curl up” to fit through those capillaries. Remember a normal red blood cell is around 7.5 µm in diameter.

Only when this process of “squeezing” through capillaries can happen, the supply of oxygen is guaranteed throughout the whole body.

Some red blood cells are however not optimally formed. To a certain extent this is normal as there are 2 million red blood cells formed per second. Usually there are around 85% to 89% of red blood cells developed properly.

By looking at the red cell distribution width value one can see how many red blood cells have a deviating form factor. If 85% to 89% are usually normally developed the RDW value then should range between 11% and 15%.

What are RDW-SD and RDW-CV markers?

RDW-SD and RDW-CV are parameters that are analyzed as part of the red blood cell blood analysis:

RDW-CV = Coefficient of Variation
RDW-SD = Standard Deviation

One important factor to mention now is that when we are looking at the red cell distribution width, we are not looking at the actual width (or diameter) of the individual red blood cells. We are looking at the width of the curve that the blood analyzing machine spits out.

So a higher or lower RDW-CV value would not indicate how much bigger or smaller the actual red blood cells are (=diameter), but rather how big the variation in cell size and volume is.

Mathematically, the RDW-CV is calculated with the following formula:

RDW-CV = (Standard deviation of MCV ÷ MCV) × 100.

Let’s look at this formula a little closer:

Mean corpuscular volume (=MCV), also called mean cell volume, is a measure of the average volume of a red blood cell. The normal range of a MCV value ranges between 80 to 96 fl (=femtoliter). This means that on average a red blood cell volume is, let’s say, 90 fl. If now the standard deviation from this curve is, let’s say, 10 fl then the RDW-CV value would be 11.1% and therefore in the normal range.

The RDW-SD is an actual measurement of the width of the red cell distribution curve in femtoliters (fL) and not percent. The width of the distribution curve is measured at the point that is 20% above the baseline (aka frequency level). Since the RDW-SD is an actual measurement, it is not influenced by the MCV and more accurately reflects the red cell size variance. The RDW-SD normal value, which is the width of the volume curve, is between 39 and 46 fL.

What if my RDW results are normal?

A person with a normal result may still have an underlying condition. Doctors often compare RDW results with those of a mean cell volume (MCV) test.

Results may show:

  • Normal RDW and normal MCV
    • People with normal results may still have anemia caused by a chronic medical condition or blood loss.
  • Normal RDW and low MCV
    • This combination may indicate anemia caused by a chronic condition or thalassemia (a blood disorder in which the body makes an abnormal form of hemoglobin).
  • Normal RDW and high MCV
    • This can indicate a liver condition or alcohol abuse. Or, a person may have this result because they are on antiviral drugs or chemotherapy. If other blood characteristics are also affected, this can suggest aplastic anemia, a rare disorder caused by inadequate blood cell production.

To confirm a diagnosis, a doctor will compare the results of the RDW test with those of the MCV measurement.

Please also refer to our Blog post titled: The Relationship Between RDW and Autoimmune Diseases: What You Need to Know.

References:

- BAIN, B. J. Diagnosis from the blood smear. N Engl J Med, v. 353, n. 5, p. 498-507, 2005.

- BARNES, P. W. et al. The international consensus group for hematology review: suggested criteria for action following automated CBC and WBC differential analysis. Lab Hematol, v. 11, n. 2, p. 83-90, 2005.

- BESSMAN, J. A. Red cells. In: BESSMAN, J. A. (Ed.). Automated blood counts and differentials: a practical guide. Baltimore: The Johns Hopkins University Press, 1986. p. 5-56.

- BUTTARELLO, M.; PLEBANI, M. Automated blood cell counts: state of the art. Am J Clin Pathol, v. 130, n. 1, p. 104-16, 2008.

- CAPORAL, F. A.; COMAR, S. R. Evaluation of RDW-CV, RDW-SD, and MATH-1SD for the detection of erythrocyte size heterogeneity observed by optical microscopy. Int J Lab Hematol, v. 35, suppl. 1, p. 44, 2013.

What does it mean if your RDW-CV (Red Cell Distribution Width) in % result is too high?

What if my RDW count is high?

If your red blood cells are unequal in size this is called anisocytosis. “Aniso” means unequal, and “cytosis” refers the characteristics, features and the number of cells. Anisocytosis itself is a nonspecific term, as there are several different ways in which cells can be unequal. The condition is prominent in cases of iron deficiency anemia. Iron is mostly stored in red blood cells, which help carry and store oxygen in the blood. A lack of iron in the blood leads to a reduction of red blood cells.

Symptoms of anisocytosis:

When the shape and size of red blood cells are not correct, then oxygen is not being transported around the body as efficiently as it should be.

This can lead to:

- tiredness

- shortness of breath

- dizziness

- headache

- cold hands and feet

- pale skin

- chest pain

A person may have:

→ High RDW and normal MCV. This suggests a deficiency of iron, B-12, or folate. It may also indicate chronic liver disease.

→ High RDW and low MCV. This suggests iron deficiency or microcytic anemia.

→ High RDW and high MCV. This indicates a lack of B-12 or folate. It can also suggest macrocytic anemia or chronic liver disease.

Can one lower the RDW?

Because several factors can cause a high RDW result, lowering the variation in red blood cell size varies according to each case. A doctor can advise how best to do this, depending on the root cause.

For those who are susceptible to a high RDW, it may help by:

Eating a more balanced diet: A nutritious diet can help prevent deficiencies of iron, folate, and vitamin B12, which contribute to raised RDW levels. However, if an individual has digestive issues affecting how they absorb nutrients from food, they may need to get nutrients in another way, such as through B12 injections.

Stopping to smoke: People who smoke can have elevated RDW. Therefore, quitting smoking may help reduce RDW and provide many other health benefits.

Avoiding to drink alcohol: Excessive alcohol can damage Red blood cells and decrease vitamin B12 and folate absorption.

Getting sufficient sleep: Getting 7 to 8 hours of sleep can result in lower RDW levels.

Exercising regularly: People with sedentary lifestyles have higher RDWs. Excercising regularly can lower RDW levels.

What does it mean if your RDW-CV (Red Cell Distribution Width) in % result is too low?

What if my RDW count is low?

A low RDW means that the red blood cells vary little in size. This could be due to the following:

→ Macrocytic anemia. A blood disorder in which not enough RBCs are produced, but the ones that are present are large.

→ Microcytic anemia. A condition in which lots of small red blood cells are present.

In these two disorders the red blood cells do not vary much in size because they are either all small or all large.

------------------------

Red Cell Distribution Width (RDW) is a measure of the variation in size of your red blood cells. It is usually reported as part of a standard complete blood count (CBC) test. The RDW can be presented in two ways: RDW-SD (standard deviation) and RDW-CV (coefficient of variation). RDW-CV is calculated by dividing the standard deviation of red blood cell width by the mean corpuscular volume (MCV) and multiplying by 100 to get a percentage.

A low RDW-CV value means that there is less variation in the size of red blood cells – they are more uniform in size. Generally, red blood cells should be fairly uniform in size. Normal ranges for RDW-CV usually fall between 11.5% and 14.5%, but these ranges can vary slightly depending on the laboratory.

A low RDW-CV level is often not a concern if the rest of the complete blood count parameters (like MCV, hemoglobin, etc.) are normal. It is less common and less clinically significant than a high RDW level, which can indicate a variety of conditions including different types of anemia, recent blood transfusion, or bone marrow disorders.

However, it is important to interpret these results in the context of the complete blood count and other clinical findings. A healthcare provider can provide a comprehensive evaluation and explain what a low RDW-CV level means in your specific case.

Frequently asked questions

Healthmatters is a highly-personalized health dashboard.

Instead of searching for your lab results in different places or tracking them down from different providers, Healthmatters houses, organizes, and interprets them all in one central location.

With a Healthmatters account, you can dive into the details of each biomarker and gain insights into the meaning behind your medical test data, anytime, anywhere.

For our professional users, Healthmatters provides intuitive tools that not only streamline analysis but also save valuable time when delving into your client's lab report history.

Healthmatters.io personal account provides in-depth research on 4000+ biomarkers, including information and suggestions for test panels such as, but not limited to:

  • The GI Effects® Comprehensive Stool Profile,
  • GI-MAP,
  • The NutrEval FMV®,
  • The ION Profile,
  • Amino Acids Profile,
  • Dried Urine Test for Comprehensive Hormones (DUTCH),
  • Organic Acids Test,
  • Organix Comprehensive Profile,
  • Toxic Metals,
  • Complete Blood Count (CBC),
  • Metabolic panel,
  • Thyroid panel,
  • Lipid Panel,
  • Urinalysis,
  • And many, many more.

You can combine all test reports inside your Healthmatters account and keep them in one place. It gives you an excellent overview of all your health data. Once you retest, you can add new results and compare them.

If you are still determining whether Healthmatters support your lab results, the rule is that if you can test it, you can upload it to Healthmatters.

While we work with many popular labs, we welcome reports from lots of other places too.

It's as simple as this: if you can get a test done, you can upload it to Healthmatters and we can interpret results from any lab out there. If laboratories can analyze it, we can interpret it.

If you’re on the hunt for a specific biomarker, contact us and we'll add it to our database. Anything from blood, urine, saliva, or stool can be uploaded, understood, and tracked with your Healthmatters account.

There are two ways to add your test reports to your Healthmatters account. One option is to input the data using the data entry forms. The other method is to utilize our "Data entry service."

Our data entry forms offer an easy, fast, and free way for you to input the reports yourself. Self-entry allows you to add an unlimited number of reports at no cost. We make the self-entry process user-friendly, providing dozens of templates that pre-populate the most popular laboratory panels and offering instant feedback on entered values.

For those who prefer assistance, we offer a "Data entry service" to help you input your data. Simply attach an image or file of your lab test results, and a qualified team member from our data entry team will add the results for you.

We support various file types, including PDFs, JPGs, or Excel. This service is particularly useful if you have many reports to upload or if you're too busy to handle the data entry yourself.

Our special data entry service makes it easy to add your results to your private dashboard. Just attach an image or a file of your lab test results, and our skilled data entry team will do the work for you. It's all done by humans, ensuring that your data is entered accurately and with personal care for each client.

Depending on your account, the data entry service can be included for free or come at an additional cost of $15 per report.

For users on the Complete monthly plan, the first report is entered free of charge, and each additional report incurs a fee of $15.

Unlimited account holders enjoy the entry of ten reports without charge. Subsequent reports are subject to a $15 fee per report.

Additionally, users on the Complete plan can upgrade to a yearly subscription from the account settings. The annual subscription includes a data entry service for five reports.

The Unlimited plan is a one-time purchase for $250, and it covers your account for a lifetime with no additional payments.

For the Complete plan, the cost is $15 per month. You have the flexibility to cancel it anytime through your account settings, ensuring no further payments. To avoid charges, remember to cancel at least a day before the renewal date. Once canceled, the subscription remains active until the end of the current billing cycle.

Additionally, you can upgrade to the yearly Advanced plan from within your account. The annual cost is $79, and it comes with a data entry service for five reports.

You can always upgrade to a lifetime version with a prorated price from a monthly or yearly subscription.

Simply log in and navigate to your account settings to cancel your subscription. Scroll down to locate the 'Cancel' button at the bottom of the page. Ensure you cancel at least one day before the renewal date to prevent any charges. Once cancellation is requested, the subscription remains active until the conclusion of the current billing cycle.

Our goal has been to make your Healthmatters account as intuitive as possible.

We’ve crafted multiple ways for you to navigate your data, whether you're glancing at a single report or delving into your historical test reports.

1. Graph View:

Dive into a visual journey with our biomarker graphs, showcasing over 40 data points. Combining years of results unveils trends, empowering you to make informed decisions. Our visualization tools make it a breeze to compare and understand changes over time, even if your results are from different labs. A search function and filters simplify the exploration of extensive data, allowing you to focus on what needs attention.

2. All Tests View

Explore neatly organized reports on a timeline, highlighting crucial details like dates, critical results, and lab/panel names. Each report opens up to reveal in-depth descriptions and additional recommendations for each biomarker. The history of previous results is just a click away, and you can download a comprehensive report for deeper insights. Color-coded and user-friendly, it's designed for easy reading, understanding, and navigation.

3. Table View:

For a holistic view of all biomarkers side by side, our table view is your go-to. Results are neatly displayed in a categorized and dated table, ideal for those with an extensive test history. Utilize sorting, filters, and color-coding to enhance your analysis and gain extra insights.

Yes, you can download information from your account. We can compile your labs into a CSV file. To download all your labs, you can go to Account Settings, and at the bottom of the page, you will find a link to download your information.

Yes, you can print your report. To do so, navigate to "All tests" and open the report you wish to print. You'll find a print button in the right corner of the report. Click on it, and your browser's print window will open. If you prefer to print in a bigger typeface, adjust the scale using the print window settings.

Yes, you can! We highly recommend activating Two-Factor Authentication (2FA) for your account. To do so, please navigate to the "Profile and Security" section of your account, where you will find instructions for activating 2FA.

Yes, you can. When entering values for the biomarker, you will see an "Edit Range" button. Click this button, and you'll have the option to enter a custom range.

A personal account is all about keeping your own lab test results in check. It's just for you and your personal use.

The professional account is designed for health professionals who wish to track and organize their clients' laboratory results.

To learn more about Healthmatters Pro, please refer to the professional page.

Use promo code to save 10% off any plan.


We implement proven measures to keep your data safe.

At HealthMatters, we're committed to maintaining the security and confidentiality of your personal information. We've put industry-leading security standards in place to help protect against the loss, misuse, or alteration of the information under our control. We use procedural, physical, and electronic security methods designed to prevent unauthorized people from getting access to this information. Our internal code of conduct adds additional privacy protection. All data is backed up multiple times a day and encrypted using SSL certificates. See our Privacy Policy for more details.

Navigate to Complete Blood Count (CBC)

Popular search

Haemoglobin (g/L), Hematocrit (Female range), Hematocrit (HCT) / Packed Cell Volume (PCV), Hemoglobin, Hemoglobin (Female range), Mean Cell Volume, Mean Corpuscular Hemoglobin (MCH), Mean Corpuscular Hemoglobin Concentration (MCHC), Mean Corpuscular Volume (MCV), Mean Platelet Volume (MPV), Mean RBC Iron, Mean RBC Iron Concentration, Mean RBC Volume, MXD #, MXD %, Platelet count / Platelets, Platelet Distribution Width (PDW), Platelet-large cell ratio (P-LCR), RBC (Female range), RBC Distribution Width, RDW-CV (Red Cell Distribution Width) in %, RDW-SD (Red Cell Distribution Width) in fL, Red Blood Cells (Erythrocytes / RBC), White blood cells (Leukocytes / WBC)