Recently, an automated blood analyzer, Coulter Counter Model S-plusⅡ,Ⅲ were
introduced and the distribution of red cell volume was displayed in histogram. Measured
as coefficient of variation(CV) and reported as red cell distribution width(RDW), the
heterogeneity of distribution of red cell size(the equivalent of anisocytosis in analysis of
the peripheral blood smear) now forms part of the reported automated blood counts.
We evaluated how RDW complements the MCV to improve the classification of
anemia from the blood cell counts alone between iron deficiency anemia and anemia of
chronic disorders, and to suggest the physiologic basis of a classification based on the
mean d heterogeneity of red cell size.
We studied 55 cases of normal healthy control, 71 cases of iron deficiency artemis,
and 69 cases of anemia of chronic disorders, using Coulter Counter S-Plus Ⅲ®,
from April 1983 to February 1986 in Yongdong Severance Hospital, Yonsei
University College of Medicine.
The results were as follows
1. The mean value of RDW in healthy adults was 13.2±0.8, and MCV 91.5±4.0fl
(Table 3).
2. There was significant difference between IDA(69.0±10.2fl, 18.5±3.4) and anemia of
chronic disorders(89.3±8.lfl, 14.2±2.2) in MCV and RDW(P<0.005) (Table 4).
3. In iron deficiency anemias,85.9% had decreased MCV(<83.5fl) and increased RDW
(>14.8). In anemia of chronic disorders, 60.7% had normal MCV and normal RDW ; 9
cases(13.0%) had increased RDW and decreased MCV which were not less than mean
value of IDA(69.0f1)(Tables 5).
4. In discriminant analysis, the equation of discriminant function classified iron
deficiency anemias at 83.1% of predicted group membership, and anemia of chronic
disorders at 89.9% of Predicted group membership : F=0.1(MCV) -0.058(RDW) -7.26
(Fig 2. Table 7).
5. MCV/RDW ratio of less than 5.1(mean+SD) determined the iron deficiency anemia
with 85.9% sensitivity and 87.0% specificity (Fig. 3).
From these studies, it can be concluded that the RDW with MCV can be used as a
sensitive parameter of red cell anisocytosis, especially in the distinction of iron
deficiency anemia from the anemia of chronic disorders.
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