RDW Blood Test in Chennai
Tired for months, or told your haemoglobin is low without a clear reason why? The RDW blood test in Chennai measures how much your red blood cells vary in size, and that single number often points to which kind of anaemia you have. It is read together with haemoglobin and MCV, and at Unittas it comes as part of a full blood count rather than an extra visit.
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What is an RDW Blood Test?
An RDW blood test checks how much your red blood cells vary in size. Many people have this test as part of a routine blood check or when doctors want to understand the cause of anaemia or related symptoms. The RDW blood test (Red Cell Distribution Width) shows whether your red blood cells are mostly the same size or if there is a wide mix of sizes.
Red cell distribution width (RDW) describes how evenly sized your red blood cells are. Red blood cells carry oxygen around the body. In healthy people, these cells are usually similar in size. The RDW test measures how much the sizes differ from one another.
A higher RDW means the cells vary more in size. A normal or low RDW means the cells are more uniform. The test is almost always done as part of a complete blood count (CBC) and is looked at together with other results such as haemoglobin and mean cell volume (MCV).
Why Might You Need an RDW Blood Test?
Doctors may order this test if you:
- Have symptoms of anaemia such as tiredness, weakness, pale skin, dizziness or shortness of breath
- Need a routine health check that includes a full blood count
- Are being investigated for iron, vitamin B12 or folate deficiency
- Have a long-term condition that can affect blood cells
- Need help to work out the type of anaemia present
- Are being monitored after treatment for a blood-related problem
The result alone does not give a full diagnosis. It is used with other blood values and your clinical history.
How is the RDW Test Done?
The RDW test is simple and quick:
- A small blood sample is taken from a vein in your arm.
- The sample is sent to the laboratory.
- Special equipment measures the range of red blood cell sizes and calculates the RDW value.
Results are usually ready within a short time as part of the full blood count report.
Preparation for the Test
No special preparation is normally required for the RDW test itself. You can usually eat and drink as normal. If other blood tests are being done at the same time (for example fasting glucose or lipid profile), your doctor or the laboratory may ask you to fast. Always follow the specific instructions given to you.
Understanding Your RDW Results
RDW is reported as a percentage. The exact normal range can vary slightly between laboratories, but a common adult range is around 11.5% to 15%.
A high RDW is commonly linked with:
| RDW Result | What It Generally Means |
|---|---|
| Normal (approx. 11.5–15%) | Red blood cells are fairly uniform in size |
| High | Greater variation in cell size (anisocytosis) |
| Low | Cells are very similar in size (usually not a concern) |
Reference ranges vary between laboratories. Always read your report against the range printed on it, and with your doctor.
- Iron deficiency anaemia
- Vitamin B12 or folate deficiency
- Mixed nutritional deficiencies
- Recovery after blood loss or treatment of anaemia
- Certain chronic conditions
Doctors often compare RDW with MCV (average cell size) to narrow down the possible cause. Your doctor will explain your specific result in the context of your other blood values and symptoms.
Why Choose Unittas Hospital for RDW Blood Test?
At Unittas Hospital, our team makes the process straightforward and comfortable. From clear guidance before the test to careful sample collection and easy-to-understand discussion of results, we focus on supporting you at every step. With convenient locations in Tambaram and OMR Kelambakkam, flexible timings and access to experienced doctors when needed, you receive attentive, patient-centred care.
If you need a reliable RDW blood test in Chennai or want clear guidance on your results, the team at Unittas Hospital is ready to help. Book your appointment and take a simple step towards understanding your blood health better.
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RDW blood test questions
Usually no. Fasting is only needed if other tests that require it are ordered at the same time.
It means your red blood cells vary more in size than usual. This can be an early sign of iron, B12 or folate deficiency or other types of anaemia. Further tests help find the exact cause.
A low RDW is rarely a concern. It simply means your red blood cells are very uniform in size.
Yes. RDW can rise early in some deficiencies before haemoglobin drops. That is why doctors look at the full set of results.
MCV shows the average size of your red blood cells. RDW shows how much the sizes differ from one another. Both are useful together.
Mild changes can occur in pregnancy due to increased blood volume and higher nutrient needs. Your doctor will interpret the result in that context.
No. A high RDW can occur with anaemia but may also appear in other conditions. The full blood count and clinical picture are needed for proper assessment.
As part of a complete blood count, results are often available within a few hours to one working day.
Some medicines and nutritional supplements can influence blood cell production. Always tell your doctor what you are taking.
It is a standard blood draw. Most people feel only a brief sting when the needle is inserted.
Severe dehydration can sometimes influence blood concentration and related values. Staying normally hydrated is helpful.
Yes, when clinically indicated. Reference ranges may differ slightly by age, and the result is interpreted accordingly.
Your doctor may order further tests such as iron studies, vitamin levels or other investigations and will discuss the next steps with you.
If the cause is a nutritional deficiency, correcting iron, B12 or folate intake under medical guidance can help bring the value towards normal over time.
Yes. It is routinely included in most complete blood count reports done as part of health check-ups.
All diagnostic tests at Unittas
Visit our Chennai labs
Both branches run the same NABH grade lab. Walk in during clinic hours, or call us to book your visit.
Tambaram
7, Duraiswamy Reddy Street, West Tambaram, Chennai 600045
Mon to Sat, 8 am to 8 pm. Sun, 9 am to 1 pm.
OMR Kelambakkam
141/1, Kazhipattur Village, OMR Main Rd, Kelambakkam 603103
Mon to Sat, 8 am to 8 pm. Sun, 9 am to 1 pm.
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Book a CBC with RDW at Unittas, or ask for home collection, and go through the result with our physicians.
Book: RDW Blood Test
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