Red Blood Cell Distribution Width (RDW-SD)

SI UNITS (recommended)

CONVENTIONAL UNITS



* The SI unit is the recommended method of reporting clinical laboratory results

Synonym
RDW, RCDW
Units of measurement
fL, µm^3

Red cell distribution width (RDW) is a red blood cell parameter that measures variability of red cell volume/size (anisocytosis). Depending on the types of hematology analyzer instruments, RDW can be reported statistically as coefficient of variation (CV) and/or standard deviation (SD), RDW-CV and/or RDW-SD, respectively.

RDW-SD takes measurements in "fL" and basically measures the width of red cells size distribution histogram – it calculates the width at the 20% height level of the histogram. The average RBC size therefore has no effect on this parameter and you get MCV or mean corpuscular volume.

RDW-CV is expressed in percentage and is calculated from MCV and standard deviation as follows:

RDW-CV (in percentage) = 1 SD of RBC volume/MCV x 100%

SI units Conversion Calculator. Convert Red Blood Cell Distribution Width (RDW-SD) level to fL, µm^3 . Clinical laboratory units online conversion from conventional or traditional units to Si units. Table of conversion factors for Red Blood Cell Distribution Width (RDW-SD) unit conversion to fL, µm^3 .