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CBC:
Complete
Blood Count
Automated
Coulter Blood Analyzer
This
test is usually called CBC
(Complete Blood Count) with differential
(different types of
white blood cells present on microscopic examination). It is a
very common test that is done to find out if a person is anemic,
has an infection,or
may have a tendency to
bleed.
Several
components make up the test.
1.
White Blood cells
(WBC): These are
cells that usually fight infection. Each laboratory has a normal
range usually from 4,000 to 10,000. If this count is elevated it
may indicate presence of infection or steroid treatment. If the
count is low, it is usually from medications, infections,
autoimmune diseases, or blood diseases among many other causes.
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on thumbnail to enlarge
Instructors
Notes: This is a normal peripheral blood smear. The large, purple
cells are the white blood cells. The numerous small cells are red
blood cells.
There
are several types of white blood cells. Determining the
percentage of the different white blood cells is called a
differential.
A differential is performed by manually counting 100 white blood
cells from a blood smear. The percentage of each type is
determined. This is important because each type of white blood
cell has a different function and may be elevated or decreased in
various diseases. Each type of WBC has a normal range in the
laboratory. The different types of White Blood Cells are:
Neutrophils:
Normal range is 60-70%
of all White Blood Cells. Neutrophils may be elevated with
bacterial infections, burns, stress, or inflammation. A decrease
may be caused by radiation, certain drugs, vitamin B12
deficiency, or systemic lupus erythematosus.
Lymphocytes:
Normal range is 20-25%
of all White Blood Cells. Lymphocyte counts may be elevated in
viral infections, immune diseases, and some leukemias.
Low numbers may be seen
in a prolonged, severe illness, during chemotherapy, and when
high levels of steroids are present.
Eosinophils:
Normal range is 2-4% of
all White Blood Cells. Eosinophils may be elevated due to
allergies, parasitic infections, autoimmune disease or adrenal
insufieciency. A low eosinophil count could be caused by
Cushing's syndrome, certain drugs, or stress.
Monocytes:
Normal range is 3-8% of
all White Blood Cells. Monocytes may be elevated from viral or
fungal infections, tuberculosis, some leukemias, and other
chronic diseases. Low levels are rarely seen.
Basophils:
Normal range is 1/2-1% of all White Blood Cells. Elevations in
basophils may be seen in allergic responses, leukemias, cancers,
and hypothyroidism. A decrease may occur during pregnancy,
ovulation, stress, and hyperthyroidism.
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on thumbnail to enlarge
WBC's.
Clockwise from left, banded neutrophil (immature form),
eosinophil (note the red, granular cytoplasm), baseophil (note
the large, purple granules), segmented neutrophil (mature form),
lymphocyte, monocyte.
2.
Hemoglobin (Hgb) and
Hematocrit (Hct): Hemoglobin
is the iron-containing pigment of red blood cells which carries
oxygen from the lungs to the tissues. The Hematocrit is the ratio
(expressed as a percentage) of RBC's to the total blood
volume.These tests usually indicate the presence of anemia when
they are below normal range. An elevated hemoglobin and
hematocrit may occur in smokers and in polycythemia, a blood
disease where there is too many red blood cells.
3.
MCV ( Mean Corpuscular
Volume), MCH
(Mean Corpuscular Hemoglobin), MCHC (Mean Corpuscular Hemoglobin
Concentration. The
MCV, MCH, MCHC are calculations that reflect the size and
hemoglobin content of individual red blood cells.
4.
Platelet Count (PLT):
Platelets are involved in clotting and prevention of bleeding. An
increased platelet count is usually seen with malignancy, certain
blood diseases, or rheumatoid arthritis. A low platelet count may
be seen in certain blood diseases, infections, and with some
medications.
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