Red cell Distribution Width- Standard Deviation also called RDW-SD is the width measurement of the red cell distribution curve in femtoliters (fL)1.
What is Red Cell Distribution Width – SD?
RDW is a measurement from the red blood cell division curve. This curve is generated in haematology analysers and is used to determine variation in RBC size within a blood sample. RDW-SD is a measurement that measures the width of the red cell distribution curve. RDW-SD is an actual measurement and hence gives comparatively more accurate red cell size variance.
Why is Red Cell Distribution Width – SD suggested?
RDW-SD is suggested to evaluate2:
- Heart diseases.
- Liver diseases.
How is Red Cell Distribution Width – SD performed?
Following is the procedure for RDW-SD:
- Alcohol is used to clean the skin and needle.
- A nurse or technician uses a small needle to draw blood from the arm.
- The blood is collected in a plain tube attached to the needle.
- The needle is ejected from the skin, The medical professional might ask the patient to hold a piece of gauze against the site where the needle pierced to stop bleeding and then will apply a bandage
The blood sample is labelled and sent to a lab where the technician performs the RDW-SD on the sample.
What are the parameters measured in Red Cell Distribution Width – SD?
Normal RDW-SD range for an adult female is 11.9-15.5 per cent and for an adult male is 11.8-15.6 per cent.calues above this will be a high RDW-SD and will be of concern.
Preparation before performing Red Cell Distribution Width – SD
The RDW-SD test does not require any special preparation. If the blood is being drawn for other tests the patient might have to fast as prescribed by the medical professional before the test
Post-care after Red Cell Distribution Width – SD
Contact your doctor right away if you feel abnormal after your RDW-SD blood test.
Sample types in Red Cell Distribution Width – SD
The sample type in RDW-SD is a blood sample.
Side effects/risks of Red Cell Distribution Width – SD
There are no major side effects of an RDW-SD test apart from maybe minor bruising and swelling at the site from where the blood was drawn.