A case–control study of prevalence of anemia among patients with type 2 diabetes
Antwi-Bafour et al. Journal of Medical Case Reports
A case-control study of prevalence of anemia among patients with type 2 diabetes
Samuel Antwi-Bafour 0
Samuel Hammond 0
Jonathan Kofi Adjei 0
Ransford Kyeremeh 0
Alexander Martin-Odoom 0
Ivy Ekem 1
0 Department of Medical Laboratory Sciences, School of Biomedical and Allied Health Sciences, College of Health Sciences, University of Ghana , P. O. Box KB 143 Korle-Bu, Accra , Ghana
1 Medical Affairs Directorate, Korle-bu Teaching Hospital , Accra , Ghana
Background: Anemia is defined as a reduction in the hemoglobin concentration of blood, which consequently reduces the oxygen-carrying capacity of red blood cells such that they are unable to meet the body's physiological needs. Several reports have indicated that anemia mostly occurs in patients with diabetes with renal insufficiency while limited studies have reported the incidence of anemia in people with diabetes prior to evidence of renal impairment. Other studies have also identified anemia as a risk factor for the need for renal replacement therapy in diabetes. Understanding the pathogenesis of anemia associated with diabetes may lead to the development of interventions to optimize outcomes in these patients. The aim of this study was therefore to determine the prevalence of anemia among patients with type 2 diabetes. Methods: A total of 100 (50 with type 2 diabetes and 50 controls) participants were recruited for our study. Participants' blood samples were analyzed for fasting blood glucose, full blood count and renal function tests among others. The prevalence of anemia was then determined statistically. Results: A high incidence of anemia was observed in the cases. Of the patients with diabetes, 84.8 % had a hemoglobin concentration that was significantly less (males 11.16±1.83 and females 10.41±1.49) than the controls (males 14.25±1.78 and females 12.53±1.14). Renal insufficiency determined by serum creatinine level of >1.5 mg/dL, estimated glomerular filtration rate <60 ml/minute/1.73 m2, and erythropoietin levels was also observed to be high in the cases (54.0 %; with mean creatinine concentration of 3.43±1.73 and erythropoietin 6.35±1.28 mIU/mL). A significantly increased fasting blood glucose, urea, sodium, potassium, and calcium ions were observed in the cases (7.99±1.30, 5.19±1.99, 140.90±6.98, 4.86±0.53 and 1.47±0.31 respectively) as compared to the controls (4.66±0.54, 3.56±2.11, 135.51±6.84, 4.40±0.58 and 1.28±0.26 respectively). Finally, a significant association between hemoglobin concentration and fasting blood glucose was also observed in the cases. Conclusions: The findings suggest that a high incidence of anemia is likely to occur in patients with poorly controlled diabetes and in patients with diabetes and renal insufficiency.
Hemoglobin concentration; Anemia; Renal insufficiency; Diabetes
Deficiency in the oxygen-carrying capacity of blood due
to a diminished erythrocyte mass or reduction in the
hemoglobin (Hb) concentration of the blood may indicate
]. This leads to the blood not being able to meet
the body’s physiological needs. It is caused by either an
excessive destruction or diminished production of red blood
]. Anemia is associated with increased perinatal
mortality, child morbidity and mortality, impaired mental
development, immune incompetence, increased
susceptibility to lead poisoning, and decreased performance at
Anemia has a high prevalence and is considered a
public health problem affecting developing and
developed countries. It occurs at all stages of life, especially in
pregnant women and children [
]. Globally, 1.62 billion
people are anemic, corresponding to 24.8 % of the global
population. The highest prevalence of 47.4 % is in
preschool-age children while the lowest prevalence of
12.7 % is in men [
]. Data from World Health Organization
(WHO) regional estimates, which were generated for
preschool-age children, pregnant women, and
nonpregnant women, indicated that the highest proportion of
people affected are in Africa (47.5 to 67.6 %), while the
greatest number affected are in Southeast Asia where 315
million individuals in the three population groups are
]. In Ghana, anemia was ranked as the fourth
leading reason for hospital admissions and the second
factor contributing to death after a review of the disease
profile and pathology reports of selected hospitals [
Diabetes mellitus (DM) is a non-infectious disease that
also has a high prevalence worldwide [
]. It is a
carbohydrate metabolism disorder which results in
hyperglycemia due to either absolute insulin deficiency or
reduced tissue response to insulin or both [
especially when poorly controlled, leads to complications
such as nephropathy, retinopathy, and neuropathy as
well as several disordered metabolic processes including
oxidative stress which causes oxidative damage to tissues
and cells [
]. Anemia is one of the commonest blood
disorders seen in patients with diabetes [
]. Many research
studies have reported that anemia mostly occurs in
patients with diabetes who also have renal insufficiency [
A few other studies have also reported an incidence of
anemia in diabetics prior to evidence of renal impairment
]. Anemia occurs earlier and at a greater degree in
patients presenting with diabetic nephropathy than those
presenting with other causes of renal failure [
Developing countries including Ghana carry the most
significant proportion of the reported cases of anemia
whose etiology is often multifactorial. The main causes
of anemia may include: dietary iron deficiency; infectious
diseases such as malaria, hookworm, and schistosomiasis;
micronutrient deficiencies including folate, vitamin B12
and vitamin A; or inherited conditions that affect red
blood cells such as thalassemia and sickle cell disease [
Again, people with chronic illnesses such as kidney
problems, cancer, diabetes, and related conditions are
at a higher risk for developing anemia. However, the
most significant contributor to the onset of anemia is
iron deficiency which has often been used as
synonymous to anemia, and the prevalence of anemia
used as a proxy for it [
Of the cases of anemia, 50 % are therefore attributable
to iron deficiency [
], but this proportion could vary
among population groups in different areas according to
local conditions. Low dietary intake of iron, poor
absorption of iron from diets high in phytate or phenolic
compounds, and period of life when iron requirements are
especially high (that is, growth and pregnancy) are the
main risk factors of iron deficiency anemia [
loss resulting from menstruation and parasitic
infestation such as hookworm, Ascaris, and schistosomiasis
also contribute to the lowering of Hb concentration
resulting in anemia. Malaria, cancer, tuberculosis, and
HIV can also contribute to the burden of anemia. An
increase in the risk of anemia could also result from
deficiencies in copper and riboflavin. The impact of
hemoglobinopathies on anemia prevalence also needs to be
considered within some populations [
]. The different
causes of anemia may work in concert, so in a single
individual, various nutrient deficiencies, chronic illnesses and
different infestations may all play a role [
]. It therefore
remains important to establish in various populations the
role that different causative factors play in the overall
alarming prevalence of anemia [
Vitamin B12 deficiency and folic acid deficiency lead to
megaloblastic anemia that results from inhibition of
DNA synthesis during red blood cell production [
The mechanism of this phenomenon is loss of
B12dependent folate recycling, followed by folate-deficiency
loss of nucleic acid synthesis, leading to defects in DNA
synthesis. Vitamin B12 deficiency alone in the presence
of sufficient folate will not cause the syndrome.
Megaloblastic anemia that is not due to hypovitaminosis may be
caused by antimetabolites that poison DNA production
directly, such as some chemotherapeutic or
antimicrobial agents (azathioprine or trimethoprim) [
pathological state of megaloblastosis is characterized by
many large immature and dysfunctional red blood cells
(megaloblasts) in the bone marrow and by
hypersegmented neutrophils [
Anemia is also the most frequent hematological
manifestation in patients with malignant diseases [
]. It may
be the first diagnostic clue to an underlying malignant
disease and may contribute to the patient’s symptoms
from the disease as well as affect treatment decisions. It
is known that tumor-associated cytokine production is a
major factor in the anemia of malignancy. In fact,
numerous in vitro studies have illustrated the central role
of tumor necrosis factor-alpha (TNF-α) in the
pathogenesis of anemia [
]. Other cytokines, such as
interleukin6 (IL-6), IL-1 and interferon-γ, have also been shown to
inhibit erythroid precursors in vitro, albeit to a lesser
]. The duration and severity of anemia seems
to be related to the type of cancer, extent of disease, and
myelosuppressive potency of chemotherapy [
most common form of anemia seen in patients with
cancer or hematological malignancies results from the
underproduction of red cells: a hypoproliferative anemia
characterized by a low reticulocyte production index and
the absence of marrow erythroid hyperplasia despite
significant persistent anemia. Again, one of the hallmarks
of malignancy-associated anemia is the reduction in
endogenous erythropoietin (EPO) levels with respect to
the degree of anemia [
Malignancy can affect bone marrow as well (bone
marrow fibrosis) and this can also result in anemia [
Bone marrow has a rich blood supply and is therefore a
common site for a metastasis to develop [
]. Cancers of
the breast, prostate, and lung are the commonest type to
do this although almost all cancers have this capability.
Once in the marrow the cancer cells can multiply easily
and the tumor deposit enlarges, occupying more and
more of the marrow space, so reducing the amount of
blood-producing marrow and the subsequent anemia
]. There are some tumors that arise from the bone
marrow tissue itself, such as some types of leukemia and
multiple myeloma. As these are more directly involved
with the bone marrow’s function they are more
commonly associated with anemia.
A normocytic normochromic anemia is also common
in patients with a variety of inflammatory disorders and
there are many contributing factors [
inflammation, from whatever cause, IL-6 induces the liver to
produce hepcidin. Hepcidin decreases iron absorption from
the bowel and blocks iron utilization in the bone
marrow. Iron may be abundant in the bone marrow, but is
not absorbed and is not in the circulation, and so is not
available for erythropoiesis. Again, some
chemotherapeutic agents induce anemia by impairing hematopoiesis
]. In addition, nephrotoxic effects of particular
cytotoxic agents, such as platinum salts, can also lead to the
persistence of anemia through reduced EPO production
by the kidney [
]. The myelosuppressive effect of
cytotoxic agents might accumulate over the course of
chemotherapy. This results in a steady increase in the incidence
of anemia with every new cycle of chemotherapy.
Furthermore, many diseases, conditions, and factors
can cause our body to destroy its red blood cells leading
to hemolytic anemia [
]. These causes can be inherited
or acquired but sometimes the cause is not known.
Hemolytic anemia can lead to many health problems,
such as fatigue, pain, arrhythmias, and heart failure [
There are many types of hemolytic anemias and
treatment and outlook depend on what type and how severe
it is. The condition can develop suddenly or slowly and
symptoms can range from mild to severe. Hemolytic
anemia often can be successfully treated or controlled.
Mild hemolytic anemia may need no treatment whereas
severe hemolytic anemia will require prompt and proper
treatment, or it may be fatal. Inherited forms of
hemolytic anemia are lifelong conditions that may
require ongoing treatment but acquired forms may go
away if the cause of the condition is found and corrected
]. The following are some examples of diseases that
lead to hemolytic anemia: sickle cell disease, thalassemias,
hereditary spherocytosis, glucose-6-phosphate
dehydrogenase (G6PD) deficiency, pyruvate kinase deficiency,
acquired hemolytic anemias, immune hemolytic anemia,
and mechanical hemolytic anemias [
Results from a study by Rossing et al. showed a
significant association between a lower Hb concentration and
a decline in glomerular filtration rate (GFR) [
recent studies have also identified anemia as a risk factor
for the need for renal replacement therapy in diabetes
]. Furthermore, anemia has a negative impact on the
survival of patients with diabetes and is considered to be
an important cardiovascular risk factor associated with
diabetes and renal disease [
]. There is therefore a
need for more studies on the incidence and prevalence
of anemia among patients with diabetes particularly
those with renal malfunction. This study therefore aimed
to determine the prevalence of anemia due to renal
insufficiency among patients with type 2 diabetes and the
outcome showed a high incidence of anemia among
them. The findings suggest that anemia is likely to occur
in patients with diabetes with renal insufficiency,
particularly when it is poorly controlled. It is therefore
believed that presentation of the outcome will help
increase the level of awareness and understanding of
anemia among patients with diabetes, which will
eventually lead to the development of interventions to optimize
treatment outcomes in them.
The study included 100 participants, consisting of 50
participants with diabetes (15 males/35 females) and 50
participants without diabetes (14 males/36 females) who
consented to participate in the study. Mean ages
recorded for cases and controls were 55.62±10.37 years
and 44.11±15.30 years respectively (Table 1). The
medical records of the participants were examined and they
were taken through a physical examination for signs and
symptoms of anemia. However, none of them showed
any signs of anemia, possibly due to the fact that there
may be no symptoms in some people who have anemia.
Other diseases such as cancer and myelodysplasia as
well as other causes of anemia as discussed in the
introduction were ruled out among the study group.
Table 2 shows the hematological parameters of the
blood samples we analyzed that were obtained from the
study participants. Hb concentration was observed to be
significantly decreased in the cases as compared to the
controls. Ferritin and total iron-binding capacity (TIBC)
levels were found to be normal in most of the cases and
lower in the control participants who were found to be
anemic. The mean cell volumes (MCVs) were higher in
the cases than the controls.
Table 3 shows the biochemical parameters of the blood
samples we analyzed that were obtained from the study
participants. A significant increase in fasting blood
glucose (FBG) concentration was observed in the cases
compared to controls (p=0.000). Significant increases in
urea, sodium (Na), potassium (K), and calcium (Ca)
concentrations were also observed in the cases as compared
to controls. Creatinine concentrations were almost
similar in both cases and controls although they were on the
high side. EPO and estimated glomerular filtration rate
(eGFR) levels were lower in cases than in controls.
Glycated Hb (HbA1c) levels were also found to be higher in
cases (particularly those with anemia) than in controls.
From Table 4, it was seen that participants with
diabetes had a high incidence of anemia in both males and
females (86.7 % and 82.9 % respectively) and 19.4 % of
the females in the control group were also anemic.
Anemia was defined by an Hb <13.0 g/dL in men and
Hb <12.0 g/dL in women [
]. Three types of anemia
Hb hemoglobin, MCV mean cell volume, TIBC total iron-binding capacity
(*p value <0.05 was considered significant)
were seen morphologically and by the MCVs obtained:
hypochromic microcytic (MCV <80 fL), normochromic
normocytic (MCV 80–95 fL), and normochromic
macrocytic (MCV>95 fL).
Renal insufficiency was determined by serum
ine level >1.5 mg/dL and eGFR <60 ml/minute/1.73 m .
A high incidence of renal insufficiency (54.0 %) was
observed in the participants with diabetes compared to
controls (Table 5). Out of the 42 (84 %) cases who were
anemic, 31 (73.8 %) showed low eGFR, which is an
indication of renal insufficiency, with the remaining 11
(26.2 %) having higher eGFR and therefore normal renal
function. Among the controls, 9 (18 %) were found to be
anemic and 7 (14 %) had high eGFR while the remaining
2 (4 %) had low eGFRs.
A positive correlation was seen between the degree of
anemia and HbA1c in patients with diabetes, supporting
the hypothesis that there is a higher incidence of anemia
among poorly controlled diabetics. Also a negative
correlation was observed between Hb and hyperglycemia
(FBG) in the diabetic population according to gender
(Fig. 1). However, only the female population’s
correlation was significant (Table 6).
Anemia is defined as a low level of Hb in the blood and
evidenced by fewer numbers of functioning red blood
cells. The WHO considers men with a Hb concentration
<13.0 g/dL or packed cell volume (PCV) <39 % anemic
and women with Hb <12.0 g/dL or PCV <36 % to be
]. Data from our study show a high incidence
of anemia (86.7 % in males; 82.9 % in females) in
participants with diabetes, predicting the necessity to assess
patients with diabetes for anemia during diagnosis and
management. HbA1c was found to be positively
correlated whereas FBG was found to be negatively correlated
with anemia in the participants with diabetes. This
suggests that the incidence of anemia is likely to increase in
poorly controlled diabetes, and therefore reducing blood
glucose levels could help reduce the risk of anemia in
Out of the 42 (84 %) cases who were anemic, 31
(73.8 %) showed low eGFR, which is an indication that
their anemia may be due to renal causes. They
subsequently presented with normochromic normocytic
anemia. The remaining 11 (26.2 %) had higher eGFRs
and possibly normal renal function; they presented with
both hypochromic microcytic (8; 19.1 %) and
normochromic macrocytic (3; 7.1 %) anemia. These were
suspected to be due to iron and B12/folate deficiency
respectively. Among the controls, nine (18 %) were
found to be anemic and here the majority (7; 14 %) had
high eGFRs and presumably normal functioning kidneys;
they presented with hypochromic microcytic (5; 10 %)
FBG (3.8–6.1 mmol/L)
Erythropoietin (4.1–19.5 mIU/mL)
Urea (7–18 mg/dL)
Na (135–145 mmol/L)
K (3.5–5.0 mmol/L)
Cl (95–105 mmol/L)
Ca (2.1–2.8 mmol/L)
Creatinine (0.6–1.5 mg/dL)
HbA1c (4–7 %, 7–8 %, ≥8.5 %)
Ca calcium, Cl chloride, eGFR estimated glomerular filtration rate, FBG fasting blood glucose, HbA1C glycated hemoglobin, K potassium, Na sodium (*p value <0.05
was considered significant)
and normochromic macrocytic (2; 4 %) anemia. The
remaining two (4 %) had low eGFRs and were deemed
to have renal insufficiency-related anemia.
A previous study reported a 15.3 % incidence of
anemia in participants with diabetes without renal
]. The study added that patients who have
poorly controlled diabetes were at greater risk of anemia
than those with controlled diabetes. Another study
reported that 7.2 % of diabetics with normal renal function
had anemia [
]. Again, other studies have reported that
20 % [
] and 19.6 % [
] of participants with diabetes
with renal insufficiency had anemia.
Anemia is a key indicator of chronic kidney disease
(CKD) but occurs earlier in the course of diabetic kidney
disease and may be more severe than previously realized
]. In patients with diabetes, anemia may be the
result of diminished EPO production by the failing kidney.
It has been suggested in other studies that this may be
due to a reduction in the number of specific
EPOsynthesizing interstitial cells and disruption of the
interstitial anatomy or vascular architecture [
]. A role
has also been suggested for autonomic dysfunction
through a relative or absolute imbalance in sympathetic/
parasympathetic tone based on the hypothesis that EPO
production may be modulated, in part, by the autonomic
nervous system [
]. Most patients with diabetes are
rarely tested for anemia and are unaware of the link
between anemia and kidney disease. A pan-European study
was therefore undertaken by Stevens et al. (2003) to
investigate the level of awareness and understanding of
anemia among patients with diabetes [
concluded that anemia has a significant impact on the
quality of life of patients with diabetes and although patients
are aware of anemia, their awareness of being tested for
anemia is low [
The estimated prevalence of anemia in people with
diabetes depends on essentially arbitrary criteria used to
define the presence or absence of anemia. Nonetheless,
studies in patients with renal impairment suggest that
deleterious effects begin with Hb <11 g/dl, meaning that
7 % of patients with diabetes may benefit from
intervention according to current guidelines [
]. Using this
definition, nearly one in four patients with diabetes (23 %)
may have anemia warranting evaluation. Although other
smaller studies have suggested that the prevalence of
anemia is increased in diabetes, their surveys have
generally selected patients with overt nephropathy [
contrast, the Predialysis Survey on Anemia Management
(PRESAM) failed to show a difference between patients
with and without diabetes [
Again a study by Thomas et al. (2003) demonstrated
that anemia is an early and common complication of
diabetes and patients at greatest risk of anemia can be
readily identified [
]. In the study, 60 % of patients with
anemia warranting investigation had eGFR <60
ml/minute−1/1.73 m2 and nearly half (46 %) of the patients
with macroalbuminuria had anemia [
]. As the risk
of anemia is strongly associated with eGFR in the study
by Thomas et al., it seems likely that supplementation
with EPO could correct anemia, particularly in the
patients with anemia and adequate iron stores .
However, potential benefits need to be balanced against the
risks of adverse arterial effects and the complications of
EPO use, including hypertension and pure red cell aplasia.
The high incidence of anemia observed in our study
may be due to the relatively small number of study
participants about half of whom presented with renal
insufficiency (Table 5). Anemia due to renal insufficiency is
primarily as a result of reduced secretion of EPO by the
failing kidneys, and anemia subsequently occurs when
creatinine clearance is less than 50 mL/minute. This is
observed earlier in patients with diabetes with renal
insufficiency or disease [
]. The high incidence of anemia
may also be due to other risk factors related to DM.
Several studies have reported factors that increase the risk
of anemia, which include; damage to renal interstitium
due to chronic hyperglycemia and consequent formation
of advanced glycation end products by increased reactive
oxygen species, and systemic inflammation as well as
Hb hemoglobin, HG hyperglycemia, *correlation is significant at p value
reduced androgen levels induced by diabetes [
limiting factor worthy of mention is our sample size; a
larger sample would have increased the power of the
study outcome. We also did not determine the HIV
status of our study participants and cannot comment on
the role of HIV on the prevalence of anemia in this
particular study population, although infection with HIV
has emerged as an additional risk factor for anemia .
The findings of our study suggest that the high incidence
of renal insufficiency observed in the participants with
diabetes, among other factors, could have influenced the
high incidence of anemic conditions seen. Anemia is
therefore likely to occur in poorly controlled diabetes
and in patients with diabetes with renal insufficiency.
Including routine hematological (Hb) tests in the
treatment of diabetes and considering factors such as
glycemic control and renal sufficiency among others
could help reduce anemia in diabetes and the possible
complications that may come with it.
The study was a case–control study conducted between
the months of March and August 2014.
Some of the materials used included: ABX Micros 60
Haematology Analyzer, Starlyte V & Human Reader
chemistry analyzers, 5 ml K2EDTA test tubes, plain test
tubes, fluoride tubes, syringes, needles, absolute
methanol, and cotton wool.
Ethical clearance for this research in accordance with
the 1964 Declaration of Helsinki and its later
amendments or comparable ethical standards was sought from
the Ethics and Protocol Review Committee of the School
of Biomedical and Allied Health Sciences, University of
Ghana, Legon (ED ID
NO:SAHS-ET./10359975/20132014). All the participants gave their informed consent
before their samples were collected.
Specimen collection and processing
From each participant, 6 ml of an overnight fasting
venous blood was collected as follows: 2 ml into an
ethylenediaminetetraacetate (EDTA) tube for hematological
profile, 2 ml into a plain tube for renal function tests
(RFTs), and 2 ml into a fluoride tube for FBG and
Full blood count test
Full blood count comprising red cell count, Hb, white
cell count and differentials, platelets as well as Hb
indices were determined from the whole blood in the EDTA
test tubes using ABX Micros 60 Haematology Analyzer
(Horiba-ABX, Montpellier, France). Ferritin and TIBC
were also done.
Renal function test
This was determined using two chemistry analyzers
(Starlyte V, USA for the electrolyte measurements; Human
Reader, Germany for urea and creatinine measurements).
Blood urea nitrogen, EPO, electrolytes, creatinine, and
eGFR were done for each participant to assess their renal
Glucose is oxidized in the presence of glucose oxidase to
form glucuronic acid and hydrogen peroxide. Hydrogen
peroxide in the presence of peroxidase reacts with
4aminophenazone and phenol to produce a colored
quinone imine complex which is measured against a reagent
blank at an absorbance of 550 nm.
The FBG for each participant was estimated from the
The data obtained were cleaned and entered into Statistical
Package for Social Scientists (SPSS) version 20.0.
Descriptive statistics such as frequencies and percentages were
used to summarize categorical variables such as gender.
Continuous variables such as Hb concentration, ferritin
concentration, and TIBC were summarized using mean
and standard deviation. An independent t-test was used to
determine mean differences between means of categorical
variables with two categories while an ANOVA was used
for those with three categories. A p value of 0.05 was
interpreted as significant.
DM: diabetes mellitus; EDTA: ethylenediaminetetraacetate; eGFR: estimated
glomerular filtration rate; EPO: erythropoietin; FBG: fasting blood glucose;
Hb: hemoglobin; HbA1c: glycated hemoglobin; IL-6: interleukin-6; MCV: mean
cell volume; PCV: packed cell volume; TIBC: total iron-binding capacity;
WHO: World Health Organization.
We the authors of this manuscript declare that none of us as authors of this
paper has any conflict of interest in relation to this manuscript. The authors
declare that they have no competing interests.
SAB participated in the design, co-supervised the research, and drafted the
manuscript. SH participated in the design of the study and carried out the
experimental work. JKA, RK, and AMO participated in the supervision of the
work and proof reading the manuscript. IE conceived the idea, participated
in the design, and co-supervised the work. All authors read and approved
the final manuscript.
We are grateful to Prof. Patrick F. Ayeh-Kumi, the Dean of the School of
Biomedical and Allied Health Sciences (SBAHS), College of Health Sciences,
University of Ghana for his assistance in the development and drafting of the
manuscript. We would also like to acknowledge the following persons for their
help in putting the manuscript together: Dr I. A. Bello, Dr Charles Brown, and Mr
David Nana Adjei, all of SBAHS.
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