关于RDW在缺铁性贫血(IDA)中的鉴别诊断的外文翻译

Importance of RDW Value in Differential Diagnosis

of Hypochrome Anemias

D.Aslan,F.GuÈmruÈk,A.GuÈrgey,and CË.Altay*

Department of Pediatric Hematology,_I hsan DogÆramacõChildren's Hospital,Hacettepe University,Ankara,Turkey

Red cell distribution width(RDW)was studied in adults carrying d-b thalassemia traits

(db-TT)who were20±40years of age(n=29),b thalassemia traits(b-TT)with an age range

of18±60years(n=49),iron de®ciency anemia(IDA)in individuals aged1±18years(n=

27),and in controls with an age range of20±40years(n=20).Although red blood cell

count,MCV,and MCH values showed no statistically signi®cant differences between db-

TT and b-TT,the mean RDW value was signi®cantly higher in db-TT(20.14 1.21)com-

pared to b-TT(14.88 1.77)(P<0.001).No difference was observed between the means of

RDW in db-TT and IDA(18.00 1.94)(P>0.05).A signi®cant rise in RDW in IDA5±7days

after initiation of iron therapy(P=0.00)which was continued to rise up to the4th week of

therapy was suggested as an important tool in differentiation of IDA from db-TT.These

observations could be kept in mind in the differential diagnosis of db-TT from b-TT and

IDA by determining the red blood cell count,red cell indices,and RDW only.Am.J.

Hematol.69:31±33,2002.ã2002Wiley-Liss,Inc.

Key words:thalassemia;iron de®ciency;RDW;microcytosis;hypochromia

INTRODUCTION

Red cell distribution width(RDW)was introduced as an important parameter in the di erential diag-nosis of iron de®ciency and b thalassemia trait(b-TT) [1,2].Increased RDW value indicates anisocytosis, and hence,in addition to iron de®ciency anemia (IDA),it could be observed in hemolytic anemias including non-transfused b thalassemia major[3].The d-b thalassemia trait(db-TT)is characterized by ele-vation of Hb F,a normal or decreased level of Hb A2,and red cell indices similar to those of b-TT. Distribution of Hb F among red cells is heteroge-neous.A rise in RDW in db-TT would be expected because of the presence of two di erent red cell populations.Indeed,two studies have shown that RDW is increased in d-b thalassemia heterozygotes [4,5].However,it seemed that this important obser-vation did not receive much attention,as these reports were not referred to in discussions of di erentiation of d-b thalassemia from b thalassemia,a thalassemia, and iron de®ciency anemia in classical textbooks. Therefore,d-b thalassemia traits,b thalassemia traits, and patients with iron de®ciency were re-evaluated in order to de®ne the importance of RDW values in distinguishing these entities.MATERIALS AND METHODS

A total of29cases of obligatory db-TTs20À40 years of age were the subjects of this study.Thalass-emia was associated with Sicilian type,gamma G type,30-kb deletion,and deletion/inversion types previously reported from Turkish subjects[6,7].For-ty-nine adult cases of b-TT with an age range of 18À60years who had common b thalassemia muta-tions that are common in the Turkish population: IVSI-110G®A,I VS I I-1G®A,or)30T®A;27 children with IDA with an age range of1À18years were also included in the study.Twenty subjects with an age range of20À40years served as controls.Age di erence in the di erent groups was ignored as it was not found to be critical in comparing RDW values.

Contract grant sponsor:TUBA,Turkish Academy of Sciences(to C.A.).

*Correspondence to:C ig dem Altay,M.D.,Professor of Pediat-rics,Department of Pediatric Hematology,_Ihsan Dog ramacõChildren's Hospital,Hacettepe University,06100Ankara,Turkey. E-mail:caltay@gen.hun.edu.tr

Received for publication10March2001;Accepted16July2001 American Journal of Hematology69:31±33(2002)

ã2002Wiley-Liss,Inc. DOI10.1002/ajh.10011

Serum iron,serum iron binding capacity,and ferritin levels were measured in all subjects.The diagnosis of IDA was made in the presence of at least three of the following criterion:Hb <11g/dl,MCV <70¯,transferrin saturation <%10,and serum ferritin level <10ng/ml.The subjects with d -b thalassemia trait or b thalassemia trait who had also iron de®ciency anemia indicated by transferrin saturation <%10and serum ferritin level <10ng/ml were excluded from the study.In IDA,RDW was measured at diagnosis and at 5À7days,2weeks,4weeks,6weeks,and 8weeks after institution of oral iron therapy (3À6mg/kg per day).Hematological studies were performed according to standard procedures.Molecular pathology of b and d thalassemia was identi®ed by previously published procedures [8].Statistical analysis used the Mann ÀWhitney U -test.

RESULTS

The RDW values in patients with d -b thalassemia and some of the other hematological parameters of various groups are given in Table I and Figure 1.The changes of RDW values associated with iron therapy in IDA are shown in Figure 2.

DISCUSSION Because of many similarities in red cell indices,RDW emerged as an important parameter to di er-entiate thalassemia trait and iron de®ciency anemia.The variation between the sizes of red cells is re¯ected by the degree of anisocytosis and as widening in the RDW value.Institution of iron therapy in iron de®-ciency anemia results in an additional rise in RDW value in 5À7days after initiation of iron therapy which coincides with reticulocytosis and continuously rises up to 4th week then starts to decline (Fig.2).In b and a thalassemia traits,almost all red cells are microcytic because de®cient synthesis of the globin chain resulting from thalassemia mutations expresses itself in all of the red cell precursors.Consequently,RDW values are relatively constant.Our observation of increased RDW in d -b thalassemia con®rms two previous studies [4,5]that also showed increased RDW in db -TT.Heterogeneous distribution of Hb F among red cells in d -b thalassemia traits suggests that although recessive pathology should express itself equally in all erythroid precursor cells,an actual in-crease in Hb F synthesis took place in F cells only.Therefore,in db -TT,the presence of a mixed red cell population,consisting of microcytic cells with un-compensated reduction in b -globin synthesis,is re-¯ected as an increase in RDW.In iron de®ciency,a signi®cant rise in RDW value starting from the 5th day of therapy is an important early ®nding for con®rmation of iron de®ciency and TABLE I.Means (+1SD)of Some of the Hematological Parameters of d -b Thalassemia Traits,b Thalassemia Traits,Iron De®ciency Anemia Patients,and Controls*

db -TT 1

b -TT 2IDA 3Normal n =29

n =49n =27n =20RDW(%)20.14Æ1.21a,b 14.88Æ1.77a,c 18.00Æ1.94c,d 12.49Æ0.63b,d Hb(g/dl)12.38Æ1.1912.41Æ1.609.35Æ0.8113.79Æ1.30MCV(¯)67.53Æ4.5766.07Æ4.2863.33Æ6.6686.40Æ2.90RBC(´1012/L) 5.51Æ0.66 5.76Æ0.82 4.64Æ0.46 4.59Æ0.46

*Superscript letters indicate statistically signi®cant values.a db -TT vs.b -TT,b db -TT vs.Normal,P <0.001;c b -TT vs.IDA,P <0.01;d IDA;vs.Normal,P <0.001.1d -b Thalassemia traits.2b Thalassemia traits.3Iron deficiency

anemia.Fig.1.RDW values of d -b thalassemia traits,b thalassemia traits,iron de®ciency anemia patients,and normal controls.In each box plot,the lower and upper bars represent the 10th and 90th percentiles,respectively;the lower and upper ends of the box represent the 25th and 75th percentiles,respectively;and the line inside the box represents the median RDW values.

32Aslan et al.

for distinguishing it from other hypochromic ane-mias.This helps to avoid further laboratory studies (Fig.2).The increase in RDW in IDA is a better parameter than is the rise of the reticulocyte count because the former continues to rise for several weeks,whereas the reticulocytosis is of short duration and

easily missed.This information is useful in the dif-ferential diagnosis of iron de®ciency and thalassemia syndromes.

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Fig.2.Changes in RDW values in IDA after iron treatment.In each box plot,the lower and upper bars represent the 10th and 90th percentiles,respectively;the lower and upper ends of the box represent the 25th and 75th percentiles,respectively;and the line inside the box represents the median RDW values.

Hypochrome Anemias and RDW 33

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