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Etiology of anemia of blood donor candidates deferred by hematologic screening
Rev Bras Hematol Hemoter. 2012;34(5):356-60
the production report of HRU-MG - data not shown). Thus, the
current study aimed to determine the prevalence and etiology
of anemia in blood donor candidates and evaluate the screening
technique used for the identification and deferral of individuals
unsuitable for donation due to anemia.
Methods
This study, carried out in blood donor candidates of
HRU-MG, was approved by the Research Ethics Committee
of the Universidade Federal do Triângulo Mineiro (UFMG -
Protocol #4532004).
In the period fromAugust 2005 to March 2006, the HRU-MG
received 13,416 candidates for blood donation, of which 2170
(16.2%) were considered clinically unfit and the remaining
11,246 were referred for hematological screening using a
sample obtained from digital pulp and processed by the manual
cyanmethemoglobin technique employing the Bioclin® kit.
According to this test, 473 (4.2%) had hemoglobin levels below
the minimum reference levels and were therefore unsuitable
for donation due to anemia; 373 (3.3%) were female and 100
(0.9%) were male.
Of this total (473), 97 blood donor candidates (21 men and
76 women) were invited and agreed to participate in this study.
These participants (Anemic Group) were matched for gender and
age with 103 successive donors suitable for donation (33 men and
70 women – Non-anemic Group).
After reading and signing an informed consent form,
blood samples were collected from both groups (Anemic and
Non-anemic) to perform laboratory tests and to investigate
the causes of anemia: hematimetry, measurement of ferritin,
qualitative hemoglobin electrophoresis in alkaline and acid pH
and quantitative electrophoresis for hemoglobin (Hb) A
2
(13,14)
.
For controls, samples were obtained at the end of donation direct
from the distal tube of the blood bag system.
The identification of abnormal hemoglobins was verified
by quantitative hemoglobin electrophoresis on cellulose acetate
in basic pH (8.4) and on agar in acidic pH (6.2)
(13)
. The Hb A2
fractions were obtained by segmentation, elution and dosage
using a densitometry of the bands resulting from electrophoresis
in cellulose acetate and a buffer solution at pH 8.5
(14)
.
The serum ferritin level (ng/dL) was measured
using an automated technique based on the principle of
immunoagglutination with amplification of the reaction by latex
and measurement by turbidimetry. Normal ferritin values using
this method are from 12 to 120 ng/dL for women and from 20 to
300 ng/dL for men.
To evaluate the method of screening for anemia employed
by the HRU-MG (manual), the hemoglobin levels of both groups
were measured by an automated method using a Coulter T-890
automated blood analyzer (Florida, USA), which also uses the
cyanmethemoglobin method. As the reproducibility of this test is
more accurate, the patients were regrouped for all other analyses
as anemic and non-anemic based on the results.
For statistical analysis, the correlation of the results
of anemia concentrations (low Hb) between the manual
and automated screening methods was assessed employing
McNemar’s chi-square test (χ
2
McN
). The proportions of cases
of anemia due to hemoglobinopathies or iron deficiency
were initially established according to gender and compared
between the Anemic and Non-anemic Groups using the chi-
square test with Yates correction (χ
2
Yates
) or Fisher’s exact test
(p
Fisher
). Measurement of the hemoglobin (g/dL) and ferritin
(ng/dL) levels were also evaluated according to gender and
compared between the Anemic and Non-anemic Groups
using the Mann-Whitney test (MW) and within each group
the hemoglobin levels (g/dL) were compared between the
automated and manual methods using the Wilcoxon signed-rank
test (W). Ferritin (ng/dL) was assessed according to gender,
group (Anemic and Non-anemic) and number of donations (<
6 and > 6 donations) using the nonparametric Kruskal-Wallis test
(KW) followed by Dunn multiple-comparison testing (p
Dunn
). The
choice of a nonparametric test was because the assumption of
data normality and the homogeneity of variances for independent
samples were not met. Differences of 5% were considered
statistically significant in all tests. The STATISTICA computer
program (version 6.0) was used to perform all analyses.
Results
On comparing the results obtained by the two screening
methods, 37 (38.1%) candidates [13 (61.9%) men and 24 (31.6%)
women], originally considered unfit for donation by the manual
technique (Bioclin® Kit) were considered fit by the automated
method (Coulter T-890). According to the automated test, these 37
candidates had hemoglobin levels within the normal range and thus
this change in diagnosis was statistically significant (χ
2
McN
= 35.1:
p < 0.0001, χ
2
McN
= 11.1: p = 0.0009 and χ
2
McN
= 22.04: p < 0.0001
for the total, for men and for women, respectively). Of the donors
originally considered suitable for donation, 15 (14.6%) individuals,
all female (21.4%), had hemoglobin levels below the normal range
according to the automated test; this was a statistically significant
difference (χ
2
McN
= 13.1; p = 0.0003). For the other analyses, the
donors were regrouped as anemic (n = 75) and non-anemic (n =
125) according to the results of the automated method. When the
hemoglobin levels (g/dL) were compared between the automated
and manual techniques, the levels of the automated test were
significantly higher for both genders in the Non-anemic Group
(p
W
= 0.002 and p
W
= 0.0001 for men and women, respectively)
compared to the manual method. While on comparing the Anemic
Group this difference was not significant (p
W
= 0.353 and p
W
=
0.810 for men and women, respectively). The hemoglobin levels
were significantly higher in the Non-anemic Group than the
Anemic Group for both genders (Table 1).
The total rate of iron deficiency of all four groups together
was 20.5%. On analyzing the iron deficiency between the groups
(Anemic and Non-anemic), six men (75.0%) of the anemic blood
donor candidates suffered from iron deficiency while among the
non-anemic blood donor candidates this rate was 15.9%, i.e. iron
deficiency was significantly associated with anemia in male donors
(χ
2
Yates
= 9.7; p = 0.002). For the females, 32.8% (n = 21) of blood
donor candidates in the Anemic Group had iron deficiency; this
was significantly higher (χ
2
Yates
= 13.1; p = 0.0003) than the female
candidates in the Non-anemic Group (7.6%; n = 6 - Table 2).