Red cell distribution width, RDW test helps to indicate variations in the shape and size of the red blood cell of a person.
They can help confirm if there is the presence of anemia and can also help find the type or cause of the conditions.
Moreover, doctors often include the RDW test as a part of a complete blood count or CBC test.
This helps to measure the number of red blood cells, white blood cells, and platelets in the blood.
However, it is essential to understand that the RDW test is not used as an isolated parameter when interpreting a complete blood count.
RDW test helps to diagnose different types of anemia and other medical conditions like thalassemia, diabetes mellitus, heart disease, liver disease, and cancer.
Keep on reading.
RDW Test
The RDW test indicates the difference in size and shape between the smallest and largest red blood samples in a sample.
Red blood cells help to transport oxygen from the lungs.
A protein inside the cell: hemoglobin binds the oxygen and carries it throughout the tissues of the body.
However, issues with hemoglobin can affect the flow of oxygen throughout the body as well as the size, shape, and health of red blood cells.
This can result in a range of health problems.
While variations are common, red blood cells or erythrocytes often have a disk shape with a diameter of about 6.2 and 8.2 micrometers.
RDW test results can be higher if more cells are larger or smaller than average.
While a higher RDW suggests that an individual has an underlying health condition.
Learn more about Blood Test: All You Need to Know here.
Uses of RDW Tests
RDW test tells the doctors if someone may have anemia and if so, they can also help indicate its type.
In most cases, the RDW test is a part of a CBC, a test that helps to measure all the components in the blood.
It includes white blood cells, platelets, and hemoglobin.
A CBC can also give a doctor an idea of what may be causing the anemia.
Moreover, it can also help to diagnose other conditions like:
- diabetes
- heart disease
- liver disease
- cancer
- thalassemia
Thalassemia is an inherited blood disorder that causes decreases in the levels of hemoglobin.
A doctor can also order a CBC if the person expereicnes dizziness, weakness, pale skin, or other symptoms of anemia.
A diet low in iron, vitamin B12, or other nutrients, a family history of blood disorders including thalassemia or sickle cell anemia, chronic illness like diabetes, HIV, or Crohn’s disease, and major blood loss injury or surgery.
However, if the results of a CBC show low levels of red blood cells or hemoglobin, this can suggest anemia.
Doctors will then try to determine the cause using the RDW and other tests.
Learn more about CBC Blood Test: What they Show here.
Preparing for the Test
Having an RDW test requires no special preparation.
If a doctor orders other blood tests in addition to RDW, the individual will need to fast for a number of hours before the test.
However, the doctor will inform them about this and any other requirements ahead of time.
Moreover, taking a blood sample for a test is a quick and simple process.
A healthcare professional will use a small needle to draw the blood from the arm of the individual.
This can cause a small scratching or stinging sensation when the needle enters the skin.
A small amount of blood will then flow from the needle into the tube.
Once the tube is full, the healthcare professional will remove the needle and may also ask the individual to hold a piece of gauze agaisnt the drawing site to stop any bleeding.
Then they will send the blood sample to a laboratory, where a technician will check the size and distribution of the RBCs.
What is the normal RDW range?
The typcial rane for RDW is about 12 to 15%.
This percentage represents how much red blood cells in a given sample deviate from the average size of the blood cells.
Moreover, doctors measure the average size of the red blood cells via a mean corpuscular volume, MCV test, which is a part of CBC.
The calculation the doctor will use for this is (RDW-SD)/(MCV)×100.
A low RDW percentage indicates that the red blood cells are not very different in size from typical measurements.
While a higher percentage means they differ in size more significantly, which can show that the body is having difficulty making red blood cells.
However, a person with a typical result may still have an underlying condition.
In order to gain a complete picture of the health of an individual, doctors can also consider the results of other blood tests.
Causes of a high RDW blood test
A high RDW test result is a high RDW count.
It can help the doctor to diagnose and differentiate between different types of anemia. The following types of anemia can cause a high RDW count:
- iron-deficiency anemia
- macrocytic anemia which causes red blood cells to become larger than average
- hemolytic anemia which is due to the body destroying red blood cells faster than it can make new ones
In comparison, other types of anemia are thalassemia, which does not cause a high RDW.
Moreover, doctors can also get more information by looking at how the RDW compares with other tests in a CBC.
For instance, a high RDW and typical MCV suggest an iron, B12, or folate deficiency or possibly chronic liver disease.
A high RDW and low MCV suggest iron deficiency or microcytic anemia. In contrast, a high RDW and high MCV indicate a lack of B12 or folate, macrocytic anemia, or chronic liver disease.
A number of conditions have links to a high RDW, including:
- alcohol use disorder
- autoimmune diseases like psoriasis, lupus, or rheumatoid arthritis
- pneumonia
- stroke
- valvular disease
- kidney disease
- chronic liver disease
- anemia related to myelodysplastic syndrome
- hereditary spherocytosis, an inherited blood disorder
However, certain factors can affect the results of an RDW test, making it less accurate.
An example of this is blood transfusions, receiving donor blood temporarily changes the composition of blood in someone, confounding the test results.
How to lower RDW
Due to a number of factors, one can have a high RDW result, lowering the variation in red blood cells varies according to each case.
A doctor can advise how best to do this, which depends on the root cause.
For those who are suspectable to a high RDW, it can help by:
Eating a Balanced Diet
A nutritious diet can help prevent deficiencies of iron, folate, and vitamin B12.
These all contribute to high levels of RDW.
However, if an individual has digestive issues that affect how they absorb nutrients from food, they may need to get nutrients in another way, like through B12 injections.
Stop Smoking
People who smoke tend to have elevated RDA.
Therefore, quitting smoking can help reduce RDW and provide other health benefits.
Avoiding Alcohol
Excessive alcohol consumption can damage RBCs and decrease vitamin B12 and folate absorption.
Getting Enough Sleep
A study that involves over 17,000 participants found that getting 7 to 8 hours of sleep is equal to the lowest RDW levels.
Exercising Regularly
People with sedentary lifestyles have higher RDW levels.
According to a study that involves over 8,000 individuals, researchers found that an increase in the number of weekly workout sessions can help reduce the risk of elevated RDW.
Outlook
The outlook for someone having a high RDW count tends to vary considerably depending on the cause of this test result.
In most cases, it indicates reversible and treatable conditions like iron, folate, or vitamin B12 deficiency.
Moreover, changing diet or taking supplements can be sufficient to treat anemia.
In other cases, however, a high RDW has links to worse health outcomes, especially in those with more serious illnesses.
For instance, a study indicates that cancer participants with a higher RDW have a greater risk of dying.
Moreover, in another study, researchers found that a high RDW count correlates with a higher mortality risk from any cause.
Therefore, it is important to speak with a doctor or seek medical advice about the next steps after getting an atypical result.
Learn more about Medical Diagnostic Imaging here.
Conclusion
RDW test measures the variation in size between blood cells in a given sample.
The results of an RDW test help to indicate the presence of anemia and some other health conditions. It can also assist in pinpointing the underlying cause.
Doctors often carry out an RDW test as a part of CBC to provide a more comprehensive picture of the health of a person.
Following a balanced diet, sleeping regularly, physical activity, and quitting smoking can help lower elevated RDW levels.
However, this will depend on its underlying cause. People with any concerns about their RDW tests should speak with a healthcare professional or seek medical advice.
