Anemia is a
lower than normal number of red blood cells (erythrocytes) in the blood,
usually measured by a decrease in the amount of hemoglobin. Hemoglobin is the
red pigment in red blood cells that transports oxygen.
There are many
types and potential causes of anemia. For information about a specific type of
anemia, see one of the following articles:
Anemia is a drop
in the number of red blood cells. This can be caused by a lack of vitamin B12
.
Causes, incidence, and risk factors
Vitamin B12 is
essential for normal nervous system function and blood cell production. The
main sources of vitamin B12 include meat, eggs, and dairy products. For vitamin
B12 to be absorbed by the body, it must bind to intrinsic
factor, a protein secreted by cells in the stomach.
Causes of
vitamin B12 deficiency include:
A
diet low in vitamin B12 (for example, a strict vegetarian diet that
excludes all meat, fish, dairy products, and eggs)
Chronic
alcoholism
Abdominal
or intestinal surgery that affects intrinsic factor production or
absorption
Confusion
or change in mental status in severe or advanced cases
Signs and tests
A physical
evaluation of the patient's neurological signs may show depressed deep tendon
reflexes, decreased position sense, decreased vibration sense, or positive Babinski
reflex. Other signs and tests include the following:
CBC results show low hematocrit
with an elevated MCV
Bone
marrow examination
Elevated
LDH
Below-normal
vitamin B12 level
Schilling
test (to determine where the deficiency in B12 absorption lies).
Treatment
Treatment
depends on the cause of the anemia:
Pernicious
anemia requires lifelong therapy with vitamin B12 injections.
Anemia
caused by a lack of vitamin B12 can be corrected by vitamin pills combined
with a more balanced
diet. It may be treated initially with vitamin B12 injections.
Anemia
caused by malabsorption is treated with vitamin B12 injections until the
condition improves.
Expectations
(prognosis)Return
to top
Treatment for
this form of anemia is usually effective.
Complications
The
signs and symptoms related to the central
nervous system may be irreversible if treatment is not begun within 6
months of when these symptoms begin.
Vitamin
B12 affects epithelial cells (cells that form the outer surface of the
body and line inner passageways). Therefore, a lack of B12 may cause a
false-positive Pap
smear.
Calling your health care provider
Call your health
care provider if you have any of the symptoms of anemia.
Prevention
Anemia caused by
a lack of vitamin B12 can be prevented through a well-balanced diet. B12 injections
can prevent anemia after surgeries known to cause vitamin B12 deficiency. Early
diagnosis and prompt treatment can limit the severity of this anemia as well as
the neurologic complications.
Megaloblastic anemia - view of red blood cells
This picture shows large, dense, oversized, red blood
cells (RBCs) that are seen in megaloblastic anemia. Megaloblastic anemia can
occur when there is a deficiency of vitamin B-12.
