Understanding Anemia
Reviewed by Barbara E. Livingston, RN,
NP, AOCN, Oncology Nurse Practitioner, The Mount Sinai Medical Center, New York,
New York.
Red blood cells (RBC)
are produced in the spongy center of large bones called the bone
marrow. Chronic diseases, cancer, cancer treatment, blood loss and poor
nutrition can all lower the number of red
blood cells. Almost all people treated with chemotherapy
will experience some degree of anemia.
Anemia following radiation therapy will depend on the area of the body receiving
the beam of radiation. Fatigue, a hallmark symptom of anemia, is the number one
symptom described by people with cancer.
Red blood cells
contain hemoglobin,
an iron-rich protein
that carries oxygen to all parts of the body. Oxygen allows all cells of the
body including those in the muscles (including the heart), nerves, and other
organs to function. The number of red blood cells circulating in the blood, the
amount of hemoglobin it contains, and the hematocrit (the ratio of red blood
cells to other components of the whole blood) are all considered when making a
diagnosis of anemia.
There are many checkpoints located in the body that
detect when oxygen levels are too low. A healthy, active individual might
compensate for lower oxygen levels (from a low hemoglobin level) simply by
increasing the number of breaths per minute. This is not a conscious effort but
an automatic one made by the body in an effort to bring more oxygen into the
blood. In contrast, it would be difficult for a person with heart and lung
disease to attempt this sort of compensation in the face of anemia.
Another way to assure there is enough oxygen circulating in the blood is
a release of more erythropoietin (EPO) from the kidneys. EPO is a growth factor
that stimulates the production and release of more red blood cells from the bone
marrow. When the kidneys detect a decrease in oxygen in the blood (as it would
with anemia) it increases EPO to step-up the release of more red blood cells.
EPO release is then slowed when the number of red blood cells and the amount of
oxygen returns to normal.
Although EPO continues to be produced in
people with cancer, their levels tend to be low. Myelosuppressive chemotherapy
agents (cisplatin, carboplatin), which are processed by the kidneys, prevent
enough EPO from being released. EPO also requires iron to work properly. People
with cancer tend to store more iron but release less into the blood stream than
people without cancer, limiting the release of EPO when it is most needed. EPO
can also be manufactured in the laboratory as recombinant human EPO and given as
treatment to people who have anemia.
Knowing the signs and symptoms of
anemia and reporting them early is key. If the anemia develops slowly however,
there may be no symptoms at all.
Symptoms of anemia include:
- Fatigue
- Weakness
- Pale skin
- Shortness of breath
- Rapid heart beat
- Lightheadness
- Dizziness
- Headache
- Bleeding
- Inability to concentrate
- Loss of sex drive.
How Red Blood Cells Are Measured
Many laboratories use their own reference standards for measuring red
blood cells, hemoglobin and hematocrit.
Normal Hemoglobin
Adult female is 12 - 16 grams per deciliter
Adult male it is 14 - 18
grams per deciliter
Red Blood Cell Count
Adult female is 4.2
- 5.4 x 106/micro liter
Adult male is 4.7 - 6.1 x
106/micro liter
Normal Hematocrit
Adult female is
37 - 47 percent
Adult male 42 - 52 percent
Anemia is diagnosed when
the hemoglobin falls below 13 g/dL for men and 12g/dL for women.
