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Introduction
Pernicious anemia is caused by a lack of intrinsic factor,
a substance needed to absorb vitamin B-12 from the
gastrointestinal tract. Vitamin B-12 is necessary for the
formation of red blood cells.
Anemia is a condition where red blood cells are not
providing adequate oxygen to body tissues. There are many
types and causes of anemia.
Pernicious anemia is a type of megaloblastic anemia.
Causes
Inadequate dietary intake (ie
vegetarian diet)
Atrophy or loss of gastric
mucosa (eg. pernicious anemia, gastrectomy, ingestion of
caustic material, hypochlorhydria, histamine 2 (H2)
blockers)
Functionally abnormal IF
Inadequate proteolysis of
dietary Cbl
Insufficient pancreatic
protease (eg, chronic pancreatitis, Zollinger-Ellison
syndrome)
Bacterial overgrowth in
intestine (eg, blind loop, diverticula)
Disorders of ileal mucosa (eg,
resection, ileitis, sprue, lymphoma, amyloidosis, adsent
IF-Cbl receptor, Zollinger Ellison Syndrome, use of
certain drugs, TCII deficiency)
Disorders of plasma
transport of cobalamin (eg, TCII deficiency, R binder
deficiency)
Dysfunctional uptake and
use of cobalamin by cells
Symptoms
Many
cells in our body need vitamin B-12, including nerve cells
and blood cells. Inadequate vitamin B-12 gradually affects
sensory and motor nerves, causing neurological problems to
develop over time. It is important to know that the
neurological effects of vitamin B-12 deficiency may be
seen before anemia is diagnosed.
The
anemia also affects the gastrointestinal system and the
cardiovascular system. The following symptoms may indicate
pernicious anemia:
-
shortness of breath
-
fatigue
-
pallor
-
rapid heart rate
-
loss of appetite
-
diarrhea
-
tingling and numbness of
hands and feet
-
sore mouth
-
unsteady gait, especially
in the dark
-
tongue problems
-
impaired sense of smell
-
bleeding gums
-
positive Babinski's reflex
-
loss of deep tendon
reflexes
-
personality changes, "megaloblastic
madness"
Screening and Diagnostics
Tests that may indicate
pernicious anemia include:
-
CBC results that show low
hematocrit and hemoglobin with elevated MCV (low red
blood cell count with large-sized red blood cells)
-
CBC showing low white blood
count and low platelets
-
low reticulocyte count
-
bone marrow examination
(only needed if diagnosis is unclear)
-
serum LDH
-
below normal serum vitamin
B-12 level
-
Schilling test
-
measurement of serum
holotranscobalamin II
-
measurement of
methylmalonic acid (MMA)
This disease may also alter
the results of the following tests:
Treatment
Treatment of pernicious anemia requires the administration
of lifelong injections of B12. Vitamin B12
given by injection enters the bloodstream directly, and
does not require intrinsic factor. At first, injections
may need to be given several times a week, in order to
build up adequate stores of the vitamin. After this, the
injections can be given on a monthly basis. Other
substances required for blood cell production may also
need to be given, iron and vitamin C.
Prognosis
Prognosis is generally good for patients with pernicious
anemia. Many of the symptoms improve within just a few
days of beginning treatment, although some of the nervous
system symptoms may take up to 18 months to improve.
Occasionally, when diagnosis and treatment have been
delayed for a long time, some of the nervous system
symptoms may be permanent.
Because an increased risk of stomach cancer has been noted
in patients with pernicious anemia, careful monitoring is
necessary, even when all the symptoms of the original
disorder have improved.
Complications
-
People with pernicious
anemia may have gastric polyps and get gastric cancer
and gastric carcinoid tumors twice as often than the
normal population.
-
Persistent neurological
defects may be present if treatment is delayed.
-
Vitamin B-12 deficiency
affects the appearance of all epithelial cells,
therefore an untreated woman may obtain a false positive
pap smear.
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