iron-deficiency anemia is associated with high concentrations of transferrin receptor
TRANSCRIPT
8/3/2019 Iron-Deficiency Anemia is Associated With High Concentrations of Transferrin Receptor
http://slidepdf.com/reader/full/iron-deficiency-anemia-is-associated-with-high-concentrations-of-transferrin 1/3
CLIN.CHEM.4 0/5 , 7 74 -7 76 (1 99 4) #{149}e ne ra l C lin ic al Chemistry
77 4 C UN IC AL C HEMIS TR Y, V ol. 4 0, N o.5 , 1994
Iron -Defic iency Anemia Is Associa ted wi th H igh Concen tra tions o f T ransfer rin
Recep to r in Serum
Kari Punnonen ,”3 K erttu Irjala ,1 and A llan Rajam#{228}ki2
We evalu ated the use o f tran sferrin receptor (T fR ) in
serum as an in dex of iron deficiency in 19 pat ients d iag-n os ed a s h av in g iro n-d efic ie nc y a nem ia , in 1 7 p atie nts
with a nem ia o f c hro nic d is ea se , a nd in a c on tro l g ro up o f
19 nonanemic pa ti en ts who underwen t e lec ti ve ocular o r
n asophar yngea l s ur ge ry . The assessmen t o f ir on status
of th e a nem ic patients was based on the presence of
stainable iron on bone marrow e xam in atio n. In th e p a-t ients wi th i ron -de fi ci encyanemia , t he se rum TfR concen -
tra tio n w as 5 .3 ± 1.8 mg/L (mean ± SD), s ign if icant lyhigher than i n the con tro lg roup (1. 7 ± 0 .5 m g/L ) o r i n t he
pa ti en ts w it h anemia o f ch ron ic d isease (1. 6 ± 0.4 m g/L).
This study sugges ts th a t s er um TfR meas uremen t is a
r elia ble index o f ir on dep le tio n and po tentia lly o f impo r-
t ance in the d iagnos is o f i ron -de fi ci encyanemia.
IndexIngTerms: bone marrow staining/ferritin
Iron-deficiency anem ia can be caused by dietary de -
privation of iron or by iron malabsorbtion and may be
th e first clinical sign of increased blood loss. Q uite often ,
iron-deficiency anem ia w arrants extensive inve stig a-
tions of the gastrointestinal tract, given t he r el at iv ely
high probability that u lcers or malignant tumors are
the cause of excessive blood loss. The distinction be -
tween iron-deficiency anem ia and the anem ia that ac-
companies infection, inflammation, or malignancy is not
clear; th e commonly used laboratory tests do not neces-
sarily distinguish these common causes of anemia (1,2).
Conventional laboratory indices of iro n statu s include
serum iron , transferrin/total iron-binding capacity,
transferrin saturation , and ferritin . A lthough each of
these measurements has m erit, no single determination
gives a reliable index of iron status (2-4). H i g h sensi-
tiv ity as well as specificity are of s pe ci al im p or ta nc e fo r
a test of iron status, because further identification of the
cause of depletion of iron stores requires tedious clin ical
a nd la boratory inve stig ations. The absence of stainable
iron on bone marrow exam ination is generally regarded
as the only reliab le i n d e x of iron d e f i c i e n c y .
Iron delivery to erythroblasts is m ediated by the in-
teraction of plasma transferrin with cell surface trans-ferrin receptors (T ifis) (5, 6). The T ifi protein ha s tw o
identical polypeptide chains, 95 kDa each, and is pre-
sent on the surfaces of virtually all cells. In norma l
a du lt s, h ow ev er , -80% of th e receptors are in the eryth-
roid marrow (5). The number of TfRa on the c el l s ur fa ce
Departments of ’ C li ni ca l C h em i st ry and2 Hematology, Univer-sity C en tral H ospital o f T urk u, Kiinamyllynkatu 4 -8 , 2 05 20T urk u, F in la nd .
3Address correspondence to this author. Fa x 358-21-613920.Received October 4, 1 99 3; accep ted Jan uary 8, 19 94 .
reflects th e iro n req uire me nt (7). Deprivation of iron
resu lts in prompt induction of TIR synthesis (7). SolubleTfR ha s been i d e n t i f i e dn human serum and pla sm a; it
is a truncated form of tissue receptor, w ith th e trunca-
tion occurring at a site just beyond the cell m em brane
(8). R ecently, serum concentrations of T have been
suggested as a reliab le index of iron depletion (2, 6,
9-13). In earlier studies of iron depletion , the iron sta-
tus was not confirmed by bone m arrow exam ination.
Therefore, w e analyzed serum TfR in a g r o u p o f a nemic
p atien ts, an d correlated the T concentrations w ith the
type of anemia an d presence of s t a i n a b l e iron in bone
marrow.
Subjects and Me thods
Patients. A total of 36 anem ic patients participated in
th is study. Bone marrow exam inations w ere performed
on all patients to identi1y the type of anem ia an d to
study the iron stores. A ll procedures were in accordance
with the H elsinki D eclaration of 1975 , as revised in
1983 . On the basis of bone m arr ow e xamin atio ns , 19
patients (13 women and 6 men) who fu lfilled the mor-
phological cr iteria of iron defic iency and who ha d no
sta inable iron on bone marrow exam ination were de -
fined as having iron-defic iency anem ia. For a contro l
group , we used 19 age- an d sex-m atched patients (13
women and 6 men) who underwent elective ocu lar or
nasopharyngeal surgery. N o bone m arrow exam inations
were perform ed on these patients but, to exclude pa-
tients w ith anem ia or acute inflammation , w e checked
t he ir h emo gl ob in , erythrocyte indices, erythrocyte sod-
iinentation rate, and serum C-reactive protein concen-
trations and found them to be within the reference in-
tervals. Another 17 anem ic patients (10 wom en and 7
m en) were selected on the basis of bone marrow exam -
inations to form the group defined as having anem ia of
chronic disease. These patients had sta inable iron on
bone marrow exam ination (m edian storage iron 2+,
range 1+ to 4+ on a scale from 0 to 4+), and their
sideroblast count ranged from 5% to 15% . O f the 17
patients w ith chronic d isease , 8 ha d recu rre nt o r ch ron ic
infections, and the remaining 9 patients had other con-ditions related to m iscellaneous chronic d iseases.
Methods. Bone marrow was asp irated from the ster-
num , and sm ears w ere stained by the M ay-G rilnwald-
G iem sa m ethod (sta in provided by Orion D iagnostica ,
H elsink i, F in land); the iron stores were stained by the
Prussian blue m ethod . B lood counts were measured
w ith an automated analyzer (Technicon H*2; M iles,
Tarrytown, NY). Serum Tifi wa s assayed w ith a com -
m er cia lly a va ila ble kit based on a polyclonal antibody
in a sandw ich enzym e im munoassay form at (C lin igenT11;
8/3/2019 Iron-Deficiency Anemia is Associated With High Concentrations of Transferrin Receptor
http://slidepdf.com/reader/full/iron-deficiency-anemia-is-associated-with-high-concentrations-of-transferrin 2/3
V
VV
VV
V
VVE
I-
-I
12
10
8
6
4
2
0
1000
20 0
50
25 aU-
10
8
6
4
2
0
10
8
6
4
2
0
a
aaa
asaa
a
a
aa
A B C
iron-deficiencyControls anem ia
19 19
Anemia ofc hr on ic d is ea se
17
zmol (Fe)/g (transferlin).
CL IN ICALCHEM ISTRY , Vo l. 4 0 , No . 5 , 1994 775
R& D Systems, M inneapolis, M N). T he r ef er en ce range
provided by the k it m an ufa ctu re r for T analysis is
1.54 ± 0.43 mg/L (n = 1 00 0) . F er ritin w as m easured
(reference range 15-306 igfL for m en, 5-103 /LgIL for
women, according to the manufacturer) w ith an IRMA
(Spectria; Or io n D ia gn os ti ca ). Transferrin w as mea-
sured [reference range 2.1-3.4 g /L for m en, 2 .0-3.1 g/L
for w om en (14)] with a Behring Nephelom eter (Beh-
ringw erke, M arburg, G erm any) and antibodies provided
by D akopatts (G lostrup, D enm ark). Serum ir on ( re fe r-ence range 10-40 moIIL) w as m easured w ith an Iron
FZ assay (H offm ann-LaR oche, B asel, Sw itzerland),
based on a guanidine h yd ro ch lo rid e/fe rr oz in e r ea ct io n.
The transferrin index (TI) was calculated as iron (tm o1/
L)/transferrin (g/L ), as recently suggested by Beilby et
al . (15).
Resul ts and D iscuss ion
We analyzed serum T if i c on ce nt ra tio ns an d per-
formed convent ional laboratory tests in anem ic patients
an d correlated th e results w ith the type of anem ia and
presence of iron in bone marrow . A tota l of 36 anem ic
patients participated in this study, and the resu lts forb lood counts and iron status markers ar e presented in
Table 1 . Common practice in F in land includes m easur-
ing the complete blood count, serum iron , transferrin,
and ferritin when exam ining anem ic patients. In pa-
tients w ith no chronic disease these values have been
helpfu l in clinical d ecision -m ak in g. H ow ever, acute-
phase responses make the interpretation of the labora-
tory d ata difficult, given that both serum ferritin and
serum transferrin are acute-phase reactan ts, th e form er
increasing and the latter decreasing in acute illness (3 ,
1 4, 16 -1 8). Serum iron concentration is lower in pa-
tients w ith iron-defic iency anem ia than in healthy sub-
jects, but it cannot be used t o d is tin gu is h ir on -d ef ic ie nc y
anem ia from anem ia of chronic disease. In the present
study the mean seru m transferrin con cen tration was
slightly h igher in the patients w ith iron-deficiency ane-
m ia than in the controls (Table 1), but the iron satura-
tion of tra nsferrin calculated as the T I is m ore useful
th an either serum iron or serum tran sferrin alon e (15)
(F ig . 1 , top). T he mean serum ferritin concentration w as
low er in patients w ith iron-deficiency anem ia (9 ± 6
mean ± SD ) than in the controls (72 ± 89 1 zg/L ,
Table 1. Ma rk er s o f ir on status in anem i c patients andcon tro ls (mean ± SD).
Hemoglobin,g/L 138 ± 13 89 ± 19 10 3 ± 13
Meanceltvolume,fL 91±4 73±9 90±7
iron, moI/L 17.3 ± 6.3 4.3 ± 2. 5 7. 1 ± 4.0
Transferrin, g/ L 2.5 ± 0.4 3.3 ± 0.5 1.9 ± 0.5
TI 7. 1 ± 2.7 1.3 ± 1.0 3.7± 1. 5
Ferritin, Lg/L 72 ± 89 9 ± 6 28 8 ± 274
TfR, mg/L 1.7 ± 0.5 5.3 ± 1.8 1.6 ± 0.4
a
A
aA
A A
Vv; kA
X fv
ABC ABC ABC
Transferrin T I Ferritin
Transferr inReceptor (mgIL)
F ig . 1 . Serum concentrat ions of t ransfemn, TI , and fer ri tin (top), an d
of TfR (bottom) i n t h e thr ee g roups : A, c on tr ols ( n 19): 8, patients
with iron-deficiency a nemia ( n = 19): an d C, patientsw i th anem i a ofc hr on ic d is ea se ( n = 17).
mean ± SD), but was sign ifican tly inc rease d in the
patients w ith anem ia of chronic disease (288 ± 27 4
pgIL) (Table 1). Thus, the us e of ferritin as a marker of
iron defic iency is complicated by the acute-phase re -
sponses associated w ith chronic d isease.
W e evaluated the use of serum TfR as an index of body
iron status in anem ic patients and correlated the T
concentration w ith the presence of iron stores in bonemarrow . The individual values of transferrin, TI, fer-
ritin, and T are shown in Fig . 1. In the patients who
h ad an em ia fulfilling the m orphological criter ia of iron-
defic iency anem ia and no stainable iron on bone m a r r o w
exam ination, the serum TfR concentration w as 5 .3 ± 1. 8
m gfL , sign ifican tly high er than that in the control group
(1.7 ± 0.5 mgfL). In 18 of the 19 patients w ith iron-
defic iency anem ia, the serum TfR concentration was
higher than in an y of the control subjects. In the pa-
tients w ith anem ia of chronic d isease (and readily stain-
8/3/2019 Iron-Deficiency Anemia is Associated With High Concentrations of Transferrin Receptor
http://slidepdf.com/reader/full/iron-deficiency-anemia-is-associated-with-high-concentrations-of-transferrin 3/3
77 6 CUN ICAL CHEMISTRY , V ol. 4 0, N o. 5, 1994
a b l e i ron in bon e marrow), th e serum T ifi con cen tration
was 1. 6 ± 0. 4 mg/L, essential ly equal to that in the
co ntro l g ro up . The values in the control group w ere w ell
within the reference range provided by the kit m anu-
facturer. Earlier studies have varied considerably in the
concentrations reported for serum and plasma T, ap-
parently because of the d ifferent specificities of the an-
tib od ies th ey used (6).
Clearly, a m ore specific index of iron-deficient eryth-
ropoiesis is needed . Serum concentrations of T haveb een sug gested to reflect the availability of iron for
erythropoiesis (1 , 10, 11). So fa r no published studies
have correlated the serum TIE concentrations w ith the
true iron status (based on bone marrow exam ination). In
the present study, we found that h igh serum TIE con-
centrations could effectively identify the patients w ith
true iron defic iency (confirm ed on the basis of absence of
stainable iron in bone marrow ) and that serum TIE
m easurem ents could also distinguish patients w ith iron-
d eficien cy a ne mia from those w ith anem ia of chronic
d isease. TIE measurem ent seem s to provide a means of
identifying iron depletion even in patients w ith acute-
phase reactions associated w ith inflam matory condi-tions (1,2); however, the effectiveness of TI E measure-
m ents in identifying latent iron deficiency remains to be
evaluated. E arlier studies reported increased TIE con-
centrations in association w ith , e.g., increased erythro-
poiesis, hem olytic anem ias, and acute leukem ias (2, 13,
19 , 20). However, none of these conditions generally
constitutes a clinical problem in the identification of
iron-deficiency anemia. On the basis of the present
study, consistent w ith other previous reports (1,2, 10),
w e c on clu de that the serum TIE concentration is a use-
ful serum marker of iron depletion.
References1. Ferguson B J, S kikne E S, Sim pson 1C M,B aynee R I), C ook JD .S eru m tran sferrin recep tor d istin guish es th e anemia of chronicd isease fro m iron d efi ci en cy a ne m ia . J Lab Clin M ed 1992;119:385-90.2. Cazzola M, Beguin Y . New tools fo r c li ni ca l e va lu at io n ofery thron function in m an. Br J Haematol 1992;80:278-84.
3. Harju E , Pakarinen A , Larm i T . A comparison between serum
ferritin con cen tratio n an d th e amount of bone m arro w s tain ab lei ro n. S ca nd J C lin L ab Inv est 1 98 4;44 :55 5-6 .
4. B urns ER , G o ld be rg SN , Lawrence C , W enz B . C li ni ca l u ti fi ty
of s er um te sts fo r iron deficiency in hospitalized patien ts. A m JCliii Pathol 1990;93:240-5.5. Huebers HA, Finch CA. The physiology of transferrun and
transferrin receptors. Physio l Re v 1987;67:520-S2.6. C oo k J D, S kik ne 88 , Baynes RD . Serum transferrin receptor.
A nn u R ev M ed 1 993 ;4 4:6 3-7 4.7 . R ao K K, S hap iro D, Mattia E, Bridges K , K lausner RD . Effectsof alterations in cellu lar iron o n b iosy nth esis of th e transferrin
receptor in K562 c ells . M o l C ell B io l 1985;5:595-600.
8. Shih YJ, Baynes RI), H udso n B G, F lo wers CH , Skikne BS,Cook JD . Serum transferrun receptor is a truncated form of tissuereceptor . J B iol C hem 1990;265:19077-81.9. Kohgo Y , N iitsu Y , K on do H , K ato I, T sush im a N , Sasaki K , eta L S er um t ra ns fe rr in receptor as a new index of ery thropoiesis.
Blood 1987;70:1955-8.10 . S kikne E S, Flowers CH, C oo k JD . S eru m transferru n recepto r:a quantitative measure of tissue iron deficiency . B lo od 1 99 0;75 :1870-8.11 . Flowers CH , Skikne 85, Covell AM , Cook JD . The clinical
measurement o f seru m t ra ns fe rr in r ec ep to r. J Lab C lin Med1989;114:368-77.12 . Thorstensen K , Egeberg K , Rom slo I, D alhoj J, W iggers P .
Variations in s er um e ry th ro p oi et in an d tr an sf err in r ec ep to r d ur-ing phlebotom y therapy of hereditary hem ochrom atosis: a case
report. Eu r J Haematol 1991;47:219-22.13 . T horsten sen K , R om slo I . T h e t ra ns fe rr in re ce pto r: its d ia g-
nostic value and its potential as therapeutic target. Scand J ClinLa b Inves t 1993;53:113 -20.14. Rajam fiki A , Irjala K , A itio A . Im niunochem ical determ ina-
tio n o f s er um tran sferrin . S can d J Haematol 1979;23:227-31.
15. Beilby J, Olynyk J, Ching S, Prins A , Sw anson N , R eed W , etal. T ransferrin index: an alternative m eth od fo r calculating th eiron saturation of tran sferrin . C liii Chem 1992;38:2078-81.
16 . Leggett BA , Brown NN , Bryant S J, D uplock L, P ow ell LW ,H allid ay ,JW. F ac to rs a ff ec ti ng th e concentrations of ferritin inserum in a healthy Australian population . C lin Chem 1990;36:1350-5.17 . Witte DL. Can serum ferritin be effectively interpreted in th epresence of the acute-phase re sp on se ? [ Ed it or ia l] . Clin Chem1991;37:484-5.
18 . C oe ne n J LL , v an D i ei je n-V is se r MP , va n P elt J, v an D eu rse n
CTBM, Pickers M MF, Wersch ,JW J, B rom ba ch er PJ. Measure-ments of serum ferritin used to p re di ct c o nc en tr at io n s of iron in
bone marrow in anem ia of chron ic d is ea se . C l i i iChem 1991;37:560-3.19 . Kato J, K ohgo Y , K on do H , N ishisato T , S asak i K , T sush im aN , et al. C irc ula tin g tran sfe rrin re ce pto r in acute leukemias. mt JHematol 1992;56:161-5.
20 . R aaf H N, Jacob sen DW , Savon S , G reen R . Serum transferrin
receptor level is no t altered in in vasive aden ocarcin om a of the
breast. A m J C l i i iathol 1993;99:232-7.