How to Calculate RDW
The RDW, red blood cell distribution width, is an important measure calculated during a standard complete red blood cell (RBC) count. The RDW measures the deviation in the volume of the RBCs as determined by the width of the volume curve. Researchers Todd S. Perlstein, et al. have shown a link between RDW and increased mortality risk in a community-based sample. In addition, a study out of the University of Kentucky has shown that a higher RDW carries a risk of increased mortality in adults greater to or equal to 45 years in age. It is apparent that effectively calculating a person's RDW may be a useful diagnostic tool when assessing personal wellness. A medical professional should assist in calculating the RDW and discussing the results.
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Instructions
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Obtain a complete red blood cell count, including indices of the red blood cells in millions per microliter of blood, hemoglobin in grams per deciliter and the percent hematocrit.
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Calculate the standard deviation of the RBC volume.
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Calculate the mean corpuscular volume (MCV) by dividing the total hematocrit by the RBC and then multiply by 10.
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Calculate the RDW by dividing the standard deviation of the RBC volume by the MCV and multiply by 100.
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Normal RDW values range from 12 to 15 percent. If the RDW is outside of the normal range, seek the help of a certified medical professional.
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Tips & Warnings
Seeking the advice of a medical professional will help to interpret laboratory findings and ensure proper care is provided if needed.
References
- "Archives of Internal Medicine"; Red Blood Cell Distribution Width and Mortality Risk in a Community-Based Prospective Cohort; Todd S. Perlstein, et al.; 2009
- "Evidence Based Medicine"; Higher Red Blood Cell Distribution Width was Associated with Increased Risk of Mortality in Adults ≥45 Years of Age; RT Means; October 2009
- Encyclopedia of Surgery: Red Blood Cell Indices
- Photo Credit Comstock Images/Comstock/Getty Images
