Sometimes when you do a blood test, you may see a value called RDW on the report. Then you may think, 'Oh, what is this RDW?' Don't worry, it's very simple. Today, we'll talk about this blood test called RDW (Red Blood Cell Distribution Width), as simple as talking to a friend.
What is RDW (Red Cell Distribution Width)?
Simply put, this blood test called RDW looks at how many red blood cells you have, and how many different sizes and volumes those cells have. You know, it's these red blood cells that carry oxygen from the lungs throughout our bodies. This oxygen is what helps our body's cells make energy and work.
Now, the size of these red blood cells is very important. Healthy red blood cells are usually the same size, which is between 6.2 and 8.2 micrometers. However, if these red blood cells are very different sizes (that is, high variability), it can be a sign of a condition called anemia . Anemia is, simply put, not having enough healthy red blood cells to provide the oxygen your body needs. This is what we sometimes call 'anemia.'
The RDW blood test is just one test that your doctor uses to diagnose anemia or other medical conditions. The doctor uses the information from it to come to a conclusion by combining it with information from other tests.
What is the difference between the RDW test and the CBC (complete blood count)?
Your doctor may order the RDW test as part of a more detailed blood test called a Complete Blood Count (CBC) . A CBC is a blood test that provides information about many of the components of your blood, including red blood cells, white blood cells, and platelets. The CBC is like a 'health certificate' for the blood in your body.
One part of the CBC is a group of tests called RBC (Red Blood Cell Indices) . These RBC indices provide information specifically about your red blood cells. The RDW blood test is one of those tests.
RBC indicators include:
- Red Cell Distribution Width (RDW): This measures the size variability of your red blood cells. That is, how large and small the red cells are.
- Mean Corpuscular Volume (MCV): This measures the average size of your red blood cells. That is, how big a red cell is on average.
- Mean Corpuscular Hemoglobin (MCH): This measures the average amount of hemoglobin in your red blood cells. Hemoglobin is a protein that helps your red blood cells carry oxygen throughout your body and gives them their red color.
- Mean Corpuscular Hemoglobin Concentration (MCHC): This measures the average amount of hemoglobin that is concentrated (packed together, tightly packed) in your red blood cells.
All of these tests together are very helpful in diagnosing various medical conditions that may be associated with problems with your red blood cells.
What does RDW actually measure?
The word 'Red Cell Distribution Width' can be a bit confusing because it means 'width'. You might think it measures the width of your red blood cells, but it doesn't. The RDW blood test measures the variation in the size of the cells in a sample of your red blood cells. It's like seeing if the kids in a class are all the same height, or if there are a lot of tall and short kids in the mix.
'Cell distribution width' is the distance between cell sizes when plotted on a histogram . A histogram is a special type of graph that shows a range of numbers or values, such as the range of red blood cell sizes.
Imagine, if all of your red blood cells are about the same size, meaning they are healthy, those values will be clustered together in a small area on the histogram. Then the RDW value is low. That means there is little diversity.
However, if the sizes of the red blood cells are very different (some are small, some are large), those values will be spread far and wide on the histogram. That is when we say that there is a wide distribution of values. In such a case, the RDW value is high. That means there is a lot of diversity.
When is an RDW test needed?
If you have symptoms like anemia, or if you have a medical condition related to anemia, this RDW test will help your doctor know exactly what it is.
What are your symptoms?
Your doctor may recommend an RDW test to determine if anemia is the cause of your symptoms. The following are some of the most common symptoms of anemia:
- Feeling tired all the time (Fatigue). As if you have no energy to do anything.
- Shortness of breath, feeling like you're going to faint even after walking a short distance.
- Feeling cold all the time, even if others have a normal temperature, you feel cold.
- Feeling dizzy or weak.
- The skin becomes pale and dry. Sometimes, it can even become pale under the eyes.
- Headache.
The RDW blood test can also provide information about the specific type of anemia you have, as the RDW value can vary in different types of anemia.
Diseases that can cause anemia
The RDW blood test, combined with other RBC indicators, can help identify the cause of anemia. Some of the conditions that can be associated with anemia include:
- Cancer.
- Cardiovascular disease.
- Kidney disease.
- Liver disease.
- Thalassemia - This is a genetic disease.
- Chronic illnesses - examples include Crohn's disease (a disease of the digestive tract), Diabetes Mellitus , and HIV .
- Vitamin and mineral deficiencies - For example, deficiencies in things like iron , vitamin B12 , and folate . These are the most common causes of anemia.
Also, anemia can occur when a large amount of blood is lost from the body, whether due to a long-standing infection, an accident, or surgery.
How is the RDW test done?
The RDW blood test is a very simple blood test. The blood sample you take is sent to a lab. There, a specialist (usually a medical laboratory scientist) looks at your red blood cells under a microscope and checks for variations in their size. The blood sample analyzed in this way is used as a sample to get a better idea of the variation in the size of your red blood cells throughout your body.
Do you need to prepare for the RDW test?
In most cases, you don't need to do anything special to prepare for the RDW test alone. However, if your doctor has ordered several other blood tests along with the RDW test, some of those tests may require special preparation. For example, some tests may require you to fast for a few hours, meaning you won't eat or drink anything. In such cases, it's important to follow your doctor's instructions exactly, so that you can be prepared for all the diagnostic tests you need.
What to expect when doing the RDW test?
Okay, now let's see what happens when you do this RDW test, what you should expect. It's actually a very small thing, and it's done in a few minutes. It's just like having a regular blood draw.
- First, your doctor or nurse will find the best place to draw blood. Most often, this will be a vein just below your elbow, or on the back of your hand.
- Then, the area where the needle is inserted is thoroughly cleaned and wiped with an antiseptic solution. This is very important, because then no germs will enter the body.
- Next, your doctor will tie an elastic band (also called a tourniquet) just above the needle insertion site on your arm. This is done to control blood flow in your arm, make the vein more visible, and make it easier to draw blood.
- Now the blood sample is taken. When the needle goes in, you may feel a slight tingling sensation, like being bitten by an ant. It only lasts a few seconds. A small amount of blood is collected in a small bottle (vial) connected to the needle.
- After the desired amount of blood is taken, the needle is removed and a small plaster or piece of cotton is placed over the site of the bleeding, and pressure is applied to stop the bleeding.
That's it! The test is over.
After the RDW test? Are there any risks?
You can leave shortly after the blood draw is done. Sometimes the doctor will tell you to wait a few minutes to make sure you don't have any side effects.
The RDW blood test is a very safe test , with very few side effects. The area where the needle was inserted may be slightly blue or bruised. This will go away on its own in a few days. Some people may feel a little dizzy after the blood is drawn, but this feeling does not last long.
However, if the bleeding from the injection site doesn't stop, or if you start to feel nauseous or faint, tell your doctor. These side effects are possible, but they are very rare.
How do RDW results come in? What do they mean?
The test results are given as a percentage. This will help you know whether your results are within the normal range, or whether your RDW value is high or low.
What is a normal RDW value?
Your RDW value is normal, meaning that your red blood cells are all the same size. That means there is not much variation in their size. A typical RDW value is between 12% and 15% . However, keep in mind that this range can vary slightly depending on the lab that performs the test. The report you receive will clearly state what the normal range is. You can then compare your value to it.
However, a normal RDW value does not mean that you do not have any other disease that requires treatment. In some types of anemia, even if the RDW value is normal, the value of one of the other RBC indicators may be high or low. That is why a doctor only makes a decision after reviewing the entire report.
What does high RDW mean?
A high RDW value means that the size of your red blood cells is more than normal. This means that some red blood cells are too small, while others are too large. A high RDW value can be a sign of anemia or a related condition. However, your doctor will need to look at other test reports to make a definitive diagnosis. Most often, the RDW (red blood cell size variability) value and the MCV (mean red blood cell volume) value are used together to assess the health of your red blood cells.
What does low RDW mean?
A low RDW value is usually nothing to worry about, and it is not associated with any specific type of anemia.
When will I know the test report?
You can usually get your results within a few days after your blood sample arrives at the lab. If you need help understanding your results, talk to your doctor. Talk to him/her about what to do next to diagnose your condition.
Whether the RDW blood test results are high, low, or normal, a doctor cannot make a diagnosis based on that alone. However, the RDW blood test is an important piece of the puzzle that helps us understand how efficiently your red blood cells are carrying oxygen throughout your body. Therefore, it is best to ask your doctor what your RDW blood test results mean, along with the other results of your CBC test.
The most important thing to keep in mind
Okay, so we've talked a lot about the RDW blood test. Here are a few things to keep in mind:
- The RDW test measures the variation in the size of your red blood cells.
- This helps to diagnose conditions like anemia .
- This is often done as part of a test called a CBC (complete blood count) .
- An RDW result alone is not meaningful. It should be evaluated by a doctor in conjunction with other blood test results and your symptoms .
If you have any questions about your RDW value, don't hesitate to ask your doctor. Then you can get a clear understanding.
` RDW, Red Blood Cells, Blood Test, Anemia, CBC, MCV, Hemoglobin, Anemia, Blood Test, Red Blood Cells, Complete Blood Count, Hemoglobin, RDW Value
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