RDW in Blood Test – A Complete Guide

Doctors often suggest patients take a Red Cell Distribution Width test or RDW test to identify the size and volume of their red blood cells (RBCs) or erythrocytes. RBCs are essential for carrying oxygen from the lungs to other body parts. Hence, doctors might need to know about the current status of erythrocytes in your body to treat you better.

Do you wish to find out more about RDW in a blood test? Then, keep reading this article to get a complete guide.

What Is RDW in a Blood Test?

red white blood cells — (Source: thecardiologyadvisor)

The human body comprises numerous red blood cells of various shapes and sizes. Generally, these are disk-shaped, with a 6.2 to 8.2 micrometres diameter. A haemoglobin protein binds these cells with oxygen, carrying it across various tissues. If you face issues with your haemoglobin, they can negatively influence the flow of oxygen and the size, shape, and health of red blood cells. This can cause multiple health issues.

Thus, the meaning of RDW in a blood test is associated with identifying the details of the volume and size of red blood cells. It helps doctors analyse the current conditions of these cells and take precautions to avoid health issues that it might cause.

Why Is the RDW Count Needed?

The RDW test is mainly conducted for anaemic patients, as a low RBC count fails to carry adequate oxygen through the blood. Doctors can pronounce a patient as anaemic after evaluating their current RBC count. In other cases, doctors suggest the RDW test as a part of a Complete Blood Count (CBC) test. This test measures various body parts, including the blood cells. It helps to diagnose the following health issues.

Heart diseases
Diabetes
Liver diseases
Cancer
Thalassemia
Weakness and fatigue
Dizziness
Family history of blood-related disorders
Pale skin
Chronic diseases (diabetes, HIV, or Crohn’s disease)
Diet with low vitamin B12, iron, etc.
Significant blood loss due to an injury

How to Measure RDW Count in Blood Test?

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 (SD) of the mean corpuscular volume (MCV) by the MCV and multiply the result by 100 (RDW-SD)/(MCV)×100). It helps them to gain an understanding of the percentage value RBC size heterogeneity in the body.

What Is a Normal RDW Count Range?

Now, you must be curious to know the normal range of RDW in a blood test. An RDW count of 12%-15% is considered normal and healthy for most people. This percentage represents the amount of RBC count in the given blood sample. If your result displays this percentage, you are under no threat of having a blood-related disorder. However, you might need other medical tests to prove it further.

What Does It Mean If Your RDW Count Is High?

If your blood test generated RDW count is higher than 15%, it means your RDW count is high. The following types of anaemia can cause a high RDW count.

Iron-deficiency anaemia
Macrocytic anaemia
Microcytic anaemia
Haemolytic anaemia

Many reasons can be responsible for causing a high RDW count, such as high alcohol consumption. In addition, having a high RDW count can indicate developing the following conditions.

Hereditary spherocytosis
Chronic liver disease
Kidney disease
Valvular disease
Stroke
Colorectal cancer

Therefore, if you have a high RDW count, it is advisable to consult doctors and start further medical tests and treatments immediately.

What Does It Mean If Your RDW Count Is Low?

If your RDW is lower than 12%, it indicates a low RDW count. The meaning of low RDW blood test count usually refers to a normal situation. It means that your RBCs or red blood cells are uniform in size and shape. In such cases, these cells are likely to perform well for your body and reduce the chances of developing any blood-related disorders.

Thus, as you can see, RDW in a blood test can be essential to understanding the condition and functions of RBCs in the human body. However, high RDW means these cells are not uniform, resulting in future complications. Thus, if your RDW count is higher than normal, take proper consultations with the healthcare professionals and avoid future diseases.

Frequently Asked Questions

✓ Is high RDW serious?

It depends on your current health conditions. If you have other conditions triggering higher RDW, it might bring cardiovascular diseases and heart failure risks.