RDW Blood Test

What Does Normal, Low and High RDW Blood Test Means

Red cell distribution width is denoted as RDW (RDW-CV or RCDW and RDW-SD) and it is mainly used in the medical laboratory during blood testing activity. RDW blood test is usually considered to be part of a complete blood test that doctors adopt in order to determine the cause of certain conditions in some patients.

In this post, you will discover the meaning of RDW in a blood test and what it means for your health. This blood testing activity is considered to be very important as far as the early treatment of certain body conditions is concerned.

NOTE: You may also get more information about MPV Blood Test: What It Means and What It Tells About Your Health

What is a Red Cell Distribution Width Test?

According to Wikipedia, the RDW blood test is said to be a measurement of the range in size and volume of your red blood cells during complete blood count. The complete blood count testing is very important as far as blood testing is concerned since it helps doctors to diagnose certain health conditions.

According to doctors on WebMD, red blood cells are very important in the human body since they help to transport blood to various parts of the body. Any slight change in the size or volume can imply that there is a problem with your body function.

Therefore, the normal size of red blood cells is about 6 to 8 micrometers (┬Ám) in diameter. High RDW in blood tests may indicate that you have a higher number of red blood cells while low RDW will imply you have a low number of red blood cells in your blood.

According to Dr. Choladda Vejabhuti Curry on WebMD, the RDW in blood tests will not confirm or rule out any form of anemia. Your doctor will conduct several tests like MCV and MCHC levels during complete blood count before confirming the health situation.

How do you prepare for the test?

After undergoing other blood tests, your doctor may advise you to have a fast some few days to the test of RDW. Therefore, it is advisable to follow special instructions given to you by your doctor prior to the day of a blood test.

RDW blood test is something that is not scary and it usually takes about five minutes. According to the mayo clinic, the doctor will take a sample of your blood from a vein and store it in a tube. The blood will then be taken in a laboratory for testing.

It is important to note that in case you continue to bleed through the needle site over several hours, seek immediate medical attention.

What Are The Meaning Of Low, Normal, And High RDW Levels?

The reference range of RDW in a blood test is 11.8% to 15.6% according to medical research by doctors on mayo clinics. However, it is important to note that the reference range of RDW usually varies depending on the laboratory performing the test.

According to Wikipedia, the normal range of RDW in human red blood cells is about 11.6% to 14.6%. However, the normal RDW in children is slightly different since children are still undergoing growth in their bone marrow.

Therefore, depending on the age of the child, the RDW usually normal range is between 12% and 14%. Always seek advice from your doctor to avoid being worried about the situation.

What does it mean if your RDW is high? Well, high RDW in blood test means that the reading value of the RDW level is far much high as compared to a normal range (above 14.5%). This could also indicate a health problem in your body that needs a diagnosis.

What does RDW mean in a blood test when it is low? Well, a low RDW blood test is when the reading value of RDW is below the normal range (below 10.2%). The doctor will determine the underlying cause and administer a diagnosis.

What RDW Blood Test Can Tell About Your Health

According to a medical report by doctors on Medscape, the blood test that involves RDW is very important when determining the health condition of a patient. The reading values of RDW in blood testing helps to check for anemia, vitamin B12 deficiency, low levels of iron, and other blood disorders.

According to doctors on Cleveland clinics, the RDW readings after blood tests can help doctors determine the cause of anemia and various methods that can help to treat it.

Your doctor will read and evaluate together RDW and MCV values before diagnosing any health conditions in your body. The following are an important factor to consider when reading and interpreting RDW and MCV (mean corpuscular volume) result:

Normal RDW and normal MCV

Anemic patients with normal RDW and MCV are said to be due to chronic blood loss or because of chronic disease in the body.

Normal RDW and low MCV

Anemic patients usually have a low mean corpuscular volume with normal RDW. This may imply that the anemia is caused by a chronic disease or an inherited blood disorder known as thalassemia.

Normal RDW and high MCV

People with liver problems, under chemotherapy treatment or have blood affected by alcohol and antivirals usually have high MCV and normal RDW during a blood test. According to doctors on the mayo clinic, patients with low lymphocyte count do have aplastic anemia.

Elevated RDW and normal MCV

What does it mean when your red blood cell count is high? Well, in case you have normal MCV and high RDW could mean that iron, vitamin B12, or folate levels are too low. Also, a chronic liver problem is marked by having high RDW and normal MCV.

Elevated RDW and low MCV

What does it mean if your blood count is high? Well, when the reading value of MCV is lower than the normal range and the RDW reading is high, it could imply that you have an iron deficiency.

Elevated RDW and high MCV

A combination of vitamin B12 or folate deficiencies, anemia, and chronic liver disease could result in both high levels of RDW and MCV.

What do Low, Normal, or High RDW Levels Mean?

The combination of RDW blood test results help to a vivid picture of the health of your red blood cells as well as diagnosing other health conditions. Here is more detailed information about the health conditions determined by RDW results.


There are certain types of cancers in the body that causes variation in size and volume distribution of your red blood cells. Therefore, the result of RDW in blood tests will help doctors diagnose the type of cancer.

According to a medical report published in the journal Haematologica, the RDW blood test is high in cancer patients and the result can also help doctors to determine the seriousness of the cancer symptoms.

According to doctors on the mayo clinic, high RDW can also be used to screen breast cancer and also determine the best form of the treatment course.

It is important to note that the RDW blood test is not the only means that is used to finally rule the presence of cancer in the blood.

Lung disease

Doctors can use high RDW values to treat patients with lung diseases. According to Dr. Clifton Titcomb on WebMD, conduction CBC for red cell distribution width can be a way of getting symptoms or results from people with pulmonary conditions.


A high level of RDW is common among women who are pregnant and this makes them also to be susceptible to anemia. According to the medical report published in the International Journal of Gynecology and Obstetrics, changes in the level of RDW among pregnant women are rampant.

However, the issue can be addressed by the doctor easily in case of iron and vitamin deficiencies. This can help to keep the health of the mother and the baby.

According to doctors on Baby Center, pregnant women who are about to give birth are also likely to experience high RDW. This is usually in preparation for giving birth.

Liver or Kidney Disease

The improper functioning of the liver and kidney due to disease could also show up during a blood tests of RDW. Liver and kidney organs in the body play a vital role in getting rid of a toxic substance in the body. Therefore, any damage to these organs due to diseases could result in an increase in the level of RDW.

According to Medical Consultant Dr. Clifton Titcomb, liver disease can be established using RDW and MCV blood test. It is easier for doctors to determine the liver problem with normal RDW and low, normal, or high MCV.

According to medical research published in 2010 in Scandinavia, impaired or damaged kidney usually results in elevated RDW in a blood test. It can also be associated with cardiovascular disease.

Autoimmune conditions

This is another condition that can result in differences in the size and volume distribution of red blood cells in the blood. According to the journal Clinical Hemorheology and Microcirculation, a blood test for RDW can help in the treatment of anemia and autoimmune disorders.

According to doctors on WebMD, lupus is an autoimmune condition that is connected to the increased level of RDW. This will be whether the person is anemic or not.


According to doctors on WebMD, diabetes is caused by the body not producing adequate or responding to the amount of insulin produced. A blood test for RDW can be checked to determine the presence of RDW.

Diabetes can trigger blood sugar levels, increased urination, and other serious complications. According to doctors at the Mayo Clinic, the diabetic patient usually experiences a high level of RDW. You can use a special diet to help manage diabetic symptoms.

High blood pressure

The health of the cardiovascular system and high blood pressure (hypertension) can be determined by RDW levels. Doctors can, however, detect blood pressure using a sphygmomanometer. According to doctors at the mayo clinic, there is a close connection between RDW and hypertension.

According to a medical report published in the journal Experimental & Clinical Cardiology, there is a link between RDW and high blood pressure. You can also get a stroke due to high blood pressure. A high level of RDW can also cause other cardiac problems.

Heart disease

According to doctors at the Cleveland clinic, a blood test for RDW can help to determine the risk of developing heart disease.  Therefore, when the level of RDW is high, the chance of developing heart attack, stroke, or peripheral artery disease is high.

According to the Journal of Thoracic Diseases, patients with cardiovascular disease usually experience a high level of RDW during a blood test. Therefore, it is import to check CBC in order to rule out the presence of heart diseases.


Any abnormalities in the RDW blood test results usually help to determine the cause of anemia. Therefore, the level of RDW reading can be used to determine the severity of anemia.

According to a medical report published in the Journal of the Indian Medical Association, a high level of RDW is usually associated with microcytic hypochromic anemia.

Therefore, you can include foods full of iron in the diet in order to the level of iron in the body. Some of the common sources of iron food are beef, seafood, and chicken, kale, cooked beans, and pumpkin or sesame seeds.


  1. Red Cell Distribution Width (RDW) Test: https://www.healthline.com/health/rdw-blood-test
  2. Red blood cell distribution width: https://en.wikipedia.org/wiki/Red_blood_cell_distribution_width
  3. Red Cell Distribution Width (RDW): https://emedicine.medscape.com/article/2098635-overview#a2
  4. RDW Blood Test: https://www.healthyandnaturalworld.com/rdw-blood-test/
  5. Red Cell Distribution Width: https://medlineplus.gov/labtests/redcelldistributionwidth.html