Red Cell Distribution Width (RDW) Overview

Which RDW measurement method is known to be less affected by mean corpuscular volume (MCV)?

What does a bimodal distribution in a red cell distribution histogram suggest?

What is the reference range for RDW-CV in adults?

What key information can RDW values provide regarding red blood cells?

Which statement about the RDW measurement methods is incorrect?

Red Cell Distribution Width (RDW)

RDW is a calculated index from RBC histograms used to identify anisocytosis (variation in red blood cell size).
Recent hematology analyzers use two methods to calculate RDW:
- RDW-CV (coefficient of variation): considers both the width of the red blood cell (RBC) distribution curve and the mean RBC size. Reference range for adults is 11.5% to 14.5%.
- RDW-SD (standard deviation): measures the actual width of the RBC distribution curve in femtoliters (fL). Reference range is 39 to 46 fL.
The earliest methods for measuring RDW were dependent on the width of the distribution curve and the mean corpuscular volume (MCV).
RDW-SD is less affected by MCV and is considered a better measure of red blood cell variability, especially in abnormal conditions.
The width of the curve in RDW-SD is measured at the point 20% above the baseline, not influenced by MCV.

Reference Ranges

MCV: 80 to 100 fL
RDW(CV): 11.5% to 14.5%

Bimodal Curve

A bimodal curve indicates two distinct populations of red blood cells.
This can be associated with conditions like anisocytosis, recent blood transfusions and schistocytes.

Explore the key concepts of Red Cell Distribution Width (RDW) and its significance in hematology. This quiz covers the different methods of calculating RDW, reference ranges for adults, and the impact of mean corpuscular volume (MCV) on RDW results. Enhance your understanding of this vital blood measurement.