Blood Donation and Transfusion
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Anemia sufferers now have expanding
options for treatment
Anemia, the lack of oxygen-carrying red blood cells, can cause severe
fatigue. Luckily, more of the people suffering from the disorder, namely
those undergoing chemotherapy and recovering from bone marrow transplants,
are finding help in recombinant erythropoietin therapy. This treatment
involves injections or IVs of genetically engineered proteins to stimulate
the body’s natural production of red blood cells, thus curing anemia.
Erythropoietin therapy for chemo patients
People who undergo chemotherapy to destroy fast-growing cancer cells
often suffer from anemia because the treatment also destroys the cells
that give rise to red blood cells. In July 2002, the Food and Drug Administration
approved the use of an erythropoietic protein for the treatment of anemia
related to chemotherapy.
This protein, Aranesp (darbepoetin alfa), works by promoting the formation
of new red blood cells. Already in use to treat patients with anemia
related to kidney failure, Aranesp is similar to EPOGEN and Procrit,
two drugs currently used to treat anemia in chemotherapy patients. But
Aranesp lasts roughly three times longer in the body. While patients
may need an injection of EPOGEN or Procrit three times a week, Aranesp
is needed just once weekly or every other week. This means fewer visits
to the doctor for treatments by chemotherapy patients. Using Aranesp
is also less expensive than EPOGEN and Procrit, although most insurers
are likely to cover the cost.
Erythropoietin therapy for bone marrow transplants
Erythropoietin therapy is also beginning to show promise for the treatment
of anemia in patients who receive donated bone marrow transplants. Bone
marrow tissue produces new blood cells, and people receive a transplant
of this tissue when their own bone marrow is unable to produce healthy
blood cells. Transplant patients often require repeated blood transfusions
to maintain healthy levels of hemoglobin, the oxygen-carrying protein
in red blood cells. In previous studies, researchers have had limited
success using very high, costly doses of erythropoietin therapy to stimulate
red blood cell production in these patients. Now a study published in
the June 2002 issue of Experimental Hematology shows low doses
of erythropoietin therapy are quite successful at boosting and maintaining
hemoglobin levels if timed correctly.
Researchers investigated the optimal timing and dosage for erythropoietin
therapy in 34 patients who had received a bone marrow transplant. In
the first trial, patients began receiving a high dose of erythropoietin
daily immediately following the transplant. In the second trial, patients
received a lower dose of the treatment three times per week beginning
sometime between 2 months and four years following the transplant. Patients
in the third trial began receiving a low dose of erythropoietin twice
a week 35 days after transplant. If hemoglobin levels were considered
insufficient (below 8 g/dL), patients received transfusions. To determine
how well the erythropoietin worked, researchers measured the hemoglobin
levels of the patients and recorded the number of transfusions required.
The researchers found patients in the first trial benefited little from
the treatment compared to control patients who did not receive any treatment.
Meanwhile, patients in the second and third trials typically did not
need transfusions after just one week of the erythropoietin therapy.
On average it took seven weeks for patients in the second trial and only
four weeks for patients in the third trial to reach normal hemoglobin
levels (12 g/dL).
While this study was small, the results suggest erythropoietin therapy
is most successful after 35 days following transplant. The researchers
believe this is when the bone marrow has recovered and is able to produce
red blood cells. This study sets the stage for a larger, more comprehensive
study of the use of erythropoietin therapy in bone marrow transplant
January 2003 Update
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Safety of the Blood Supply
Likely, the last thing anyone wants to think about when
he or she is in need of a blood transfusion is: Is this blood safe?
Yet, the question is one that needs to be answered. The answer is: safe,
safer than it ever has been, but not entirely safe.
To protect the blood supply from contamination with infectious agents,
all blood donors are screened and laboratory tests are performed to detect
disease in donated blood. How effective are these screening measures?
A recently published study reported that between 1991 and 1996 the prevalence
of hepatitis C and HIV in blood from first-time donors decreased, from
0.63% to 0.40% and from 0.030% to 0.015%, respectively. However, the
prevalence of hepatitis B, while low at 0.2%, remained constant throughout
the five years. While the incidence of hepatitis C in the general population
has decreased, the prevalence of HIV has risen. The results of the study
suggest that the safety of the blood supply is improving in part due
to donor screening, which includes questions regarding specific behavioral
risk factors for HIV. The current risk of transmitting a virus through
a transfusion is 1 in 677,000 for HIV, 1 in 103,000 for hepatitis C,
and 1 in 63,000 for hepatitis B.
As the safety of the blood supply is improving, researchers continue
to invest resources and effort into enhancing laboratory techniques that
detect viruses in donated blood. A major concern is how to catch potential
problems with blood donated during the window period between viral infection
and the development of antibodies to the virus. This problem can be avoided
by directly testing donated blood for viruses such as HIV and hepatitis
C using a technique referred to as NAT. Yet, testing every unit of donated
blood with the currently available technology would be costly and logistically
difficult. So instead, minipools of blood donations are tested.
This pooling, however, dilutes the blood and can decrease the sensitivity
of NAT testing. Evidence of this danger was found in a case of HIV infection
from transfusion. According to an investigation, two patients in Singapore
were infected with HIV when they received a blood transfusion from a
recently infected donor. The level of virus in the donated blood was
undetectable at the dilution levels currently proposed for NAT testing
in the United States. Once reasonable technology becomes widely available,
testing of individual blood donations will likely become the standard
practice. Yet, even individual testing will not entirely eliminate risk.
When considering the safety of a blood transfusion, one must understand
the risks. However, the safety of blood transfusions is equal to or even
greater than the safety of many common medications and medical procedures.
Blood is safe enough and it will get even safer. For elective procedures,
patients can talk to their doctors about autologous blood donation, that
is, that patient pre-donates some of his or her own blood
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