What Is Pernicious Anemia?
Pernicious anemia (per-NISH-us uh-NEE-me-uh) is a
condition in which the body can't make enough healthy red blood cells because
it doesn't have enough vitamin B12.
Vitamin B12 is a nutrient found in certain foods.
The body needs this nutrient to make healthy red blood cells and to keep its
nervous system working properly.
People who have pernicious anemia can't absorb
enough vitamin B12 from food due to a lack of intrinsic (in-TRIN-sik) factor, a
protein made in the stomach. This leads to vitamin B12 deficiency.
Other conditions and factors also can cause vitamin
B12 deficiency. Examples include infections, surgery, medicines, and diet.
Technically, the term "pernicious anemia" refers to vitamin B12 deficiency due
to lack of intrinsic factor. Often, vitamin B12 deficiency due to other causes
also is called pernicious anemia.
This article discusses pernicious anemia due to a
lack of intrinsic factor and other causes.
Overview
Pernicious anemia is a type of
anemia
(a condition in which your body has a lower than normal number of red blood
cells). In pernicious anemia, the body can't make enough healthy red blood
cells because it doesn't have enough vitamin B12.
Without enough vitamin B12, your red blood cells
don't divide normally and are too large. They may have trouble getting out of
the bone marrow—a sponge-like tissue inside the bones where blood cells
are made.
Without enough red blood cells to carry oxygen to
your body, you may feel tired and weak. Severe or long-lasting pernicious
anemia can damage the heart, brain, and other organs in the body.
Pernicious anemia also can cause other
complications, such as nerve damage, neurological problems (such as memory
loss), and digestive tract problems. People who have pernicious anemia also may
be at higher risk for stomach cancer.
Outlook
The condition is called pernicious ("deadly") anemia
because it was often fatal in the past, before vitamin B12 treatments were
available. Now, pernicious anemia usually is easy to treat with vitamin B12
pills or shots.
With ongoing care and proper treatment, most people
who have pernicious anemia can recover, feel well, and live normal lives.
Without treatment, pernicious anemia can lead to
serious problems with the heart, nerves, and other parts of the body. Some
effects of the condition may be permanent.
Other Names for Pernicious Anemia
Pernicious anemia is one of two major types of
"macrocystic" or "megaloblastic" anemia. These terms refer to anemia in which
the red blood cells are larger than normal. (The other major type of
macrocystic anemia is due folic acid deficiency.)
Rarely, children are born with an inherited disorder
that prevents their bodies from making intrinsic factor. This disorder is
called congenital pernicious anemia.
Vitamin B12 deficiency also is called cobalamin
deficiency, and combined systems disease.
What Causes Pernicious Anemia?
Pernicious anemia is due to a lack of intrinsic
factor or other causes, such as infections, surgery, medicines, or diet.
Lack of Intrinsic Factor
Intrinsic factor is a protein made in the stomach
that helps your body absorb vitamin B12. In some people, lack of intrinsic
factor is due to an autoimmune response.
An autoimmune response occurs when the immune system
makes antibodies (proteins) that mistakenly attack and damage the body's
tissues or cells.
In pernicious anemia, the body makes antibodies that
attack and destroy the parietal (pa-RI-e-tal) cells. These are the cells in the
lining of the stomach that make intrinsic factor. Why this autoimmune response
occurs isn't known.
As a result of this attack, the stomach stops making
intrinsic factor. Without intrinsic factor, your body can't move vitamin B12
through the small intestine, where it's absorbed. This leads to vitamin B12
deficiency.
A lack of intrinsic factor also can occur if you've
had part or all of your stomach removed. This type of surgery reduces the
number of parietal cells available to make intrinsic factor.
Rarely, children are born with an inherited disorder
that prevents their bodies from making intrinsic factor. This disorder is
called congenital pernicious anemia.
Other Causes
Besides a lack of intrinsic factor, other conditions
and factors also can cause pernicious anemia.
Malabsorption in the Small Intestine
Sometimes pernicious occurs because the body's small
intestine can't properly absorb vitamin B12. This may be the result of:
- Too many of the wrong kind of bacteria in the
small intestine. This is a common cause of pernicious anemia in older adults.
The bacteria use up the available vitamin B12 before the small intestine can
absorb it.
- Diseases that interfere with vitamin B12
absorption. One example is celiac disease. This is a genetic disorder in which
your body can't tolerate a protein called gluten. Another example is Crohn's
disease. This is an inflammatory bowel disease.
- Certain medicines that alter bacterial growth or
prevent the small intestine from properly absorbing vitamin B12. Examples
include antibiotics and certain diabetes and seizure medicines.
- Surgical removal of part or all of the small
intestine.
- A tapeworm infection. The tapeworm feeds off the
vitamin B12. Eating undercooked, infected fish may cause this type of
infection.
Diet
Less often, people develop pernicious anemia because
they don't get enough vitamin B12 in their diets. The best food sources for
vitamin B12 are meat, poultry, fish, eggs, and dairy products. You also can get
vitamin B12 from dietary supplements.
Strict vegetarians who don't eat any animal or dairy
products and don't take a vitamin B12 supplement are at risk for pernicious
anemia.
Breastfed infants of strict vegetarian mothers also
are at risk for pernicious anemia. These infants can develop anemia within
months of being born. This is because they haven't had enough time to store
vitamin B12 in their bodies. Doctors treat these infants with vitamin B12
supplements.
Other groups, such as the elderly and people who
suffer from alcoholism, also may be at risk for pernicious anemia because they
may not get the proper nutrients in their diets.
Who Is At Risk for Pernicious Anemia?
Pernicious anemia is more common in people of
Northern European and African descent.
In the United States, older people are at higher
risk for the condition. This is mainly due to a lack of stomach acid and
intrinsic factor, which prevents the small intestine from absorbing vitamin
B12. As people grow older, they tend to make less stomach acid.
Pernicious anemia also occurs in younger people and
other populations groups. You're at higher risk for pernicious anemia if
you:
- Have a family history of the condition.
- Have had part or all of your stomach removed. The
stomach makes intrinsic factor, a protein that helps your body absorb vitamin
B12.
- Have certain autoimmune disorders that involve
the endocrine glands, such as Addison's disease, type 1 diabetes, Graves'
disease, and vitiligo. Research suggests a link may exist between these
autoimmune disorders and pernicious anemia that's caused by an autoimmune
response.
- Have had part or all of your small intestine
removed. The small intestine is where vitamin B12 is absorbed.
- Have certain intestinal diseases or disorders
that prevent your body from properly absorbing vitamin B12. Examples include
Crohn's disease and intestinal infections.
- Take medicines that prevent your body from
properly absorbing vitamin B12. Examples of such medicines include antibiotics
and certain seizure medicines.
- Are a strict vegetarian who doesn't eat any
animal or dairy products and doesn't take a vitamin B12 supplement, or if you
eat poorly overall.
What Are the Signs and Symptoms of Pernicious
Anemia?
The signs and symptoms of pernicious anemia are due
to a lack of vitamin B12 (vitamin B12 deficiency). Without enough vitamin B12,
your body can't make enough healthy red blood cells. This causes
anemia.
Some of the signs and symptoms of pernicious anemia
apply to all types of anemia. Other signs and symptoms are specific to a lack
of vitamin B12.
Signs and Symptoms of Anemia
The most common symptom of all types of anemia is
fatigue (tiredness). This symptom is due to your body not having enough red
blood cells to carry oxygen to its various parts.
A low red blood cell count also can cause shortness
of breath; dizziness, especially when standing up; headache; coldness in your
hands or feet; pale skin, gums, and nail beds; and chest pain.
A lack of red blood cells also means that your heart
has to work harder to move oxygen-rich blood through your body. This can lead
to arrhythmias
(ah-RITH-me-ahs),
heart
murmur, an enlarged heart, or even
heart
failure.
Signs and Symptoms From a Lack of Vitamin B12
Vitamin B12 deficiency may lead to nerve damage.
This can cause tingling and numbness in your hands and feet, muscle weakness,
and loss of reflexes. You also may feel unsteady, lose your balance, and have
trouble walking.
Severe vitamin B12 deficiency can cause neurological
problems, such as confusion, dementia, depression, and memory loss.
Other symptoms of vitamin B12 deficiency involve the
digestive tract. These symptoms include nausea (feeling sick to your stomach)
and vomiting, heartburn, abdominal bloating and gas, constipation or diarrhea,
loss of appetite, and weight loss. An enlarged liver is another symptom.
A smooth, beefy red tongue also is a sign of
vitamin B12 deficiency and pernicious anemia.
Infants who have vitamin B12 deficiency may have
poor reflexes or unusual movements, such as face tremors. They may have trouble
feeding due to tongue and throat problems. They also may be irritable. If
vitamin B12 deficiency isn't treated, infants can have permanent growth
problems.
How Is Pernicious Anemia Diagnosed?
Your doctor will diagnose pernicious anemia based on
your medical and family histories, a physical exam, and the results from
tests.
Your doctor will want to find out whether the
condition is due to a lack of intrinsic factor or another cause. He or she also
will want to find out how severe the problem is, so it can be treated properly.
Specialists Involved
Primary care doctors, such as family doctors,
internists, and pediatricians (doctors who treat children), often diagnose and
treat pernicious anemia. Other kinds of doctors also may be involved,
including:
- A neurologist (nervous system specialist)
- A cardiologist (heart specialist)
- A hematologist (blood disease specialist)
- A gastroenterologist (digestive tract
specialist)
Medical and Family Histories
Your doctor may ask about your
signs and symptoms. He or she also may
ask:
- Whether you've had any stomach or intestinal
surgeries
- Whether you have any digestive disorders, such as
celiac disease or Crohn's disease
- About your diet and any medicines you take
- Whether you have a family history of
anemia
or pernicious anemia
- Whether you have a family history of autoimmune
disorders (such as Addison's disease, type 1 diabetes, or Graves' disease).
Research suggests a link may exist between these autoimmune disorders and
pernicious anemia that's caused by an autoimmune response.
Physical Exam
During the physical exam, your doctor may check for
pale or yellowish skin and an enlarged liver. He or she may listen to your
heart for a rapid heartbeat or
heart
murmur.
Your doctor also may check for signs of nerve
damage. He or she may want to see how well your muscles, eyes, senses, and
reflexes work. Your doctor may ask questions or do tests to check your mental
status, coordination, and ability to walk.
Diagnostic Tests and Procedures
Blood tests and procedures can help diagnose
pernicious anemia and find out what's causing it.
Complete Blood Count
Often, the first test used to diagnose many types of
anemia is a
complete
blood count (CBC). This test measures many different parts of your blood.
For this test, a small amount of blood is drawn from a vein (usually in your
arm) using a needle.
A CBC checks your hemoglobin and hematocrit
(hee-MAT-oh-crit) levels. Hemoglobin is the iron-rich protein in red blood
cells that carries oxygen to the body. Hematocrit is a measure of how much
space red blood cells take up in your blood. A low level of hemoglobin or
hematocrit is a sign of anemia.
The normal range of these levels may be lower in
certain racial and ethnic populations. Your doctor can explain your test
results to you.
The CBC also checks the number of red blood cells,
white blood cells, and platelets in your blood. Abnormal results may be a sign
of anemia, a blood disorder, an infection, or another condition.
Finally, the CBC looks at mean corpuscular
(kor-PUS-kyu-lar) volume (MCV). MCV is a measure of the average size of your
red blood cells. MCV can be a clue as to what's causing your anemia. In
pernicious anemia, the red blood cells are larger than normal
(macrocystic).
Other Blood Tests
If the CBC results confirm that you have anemia, you
may need other blood tests to find out what type of anemia you have.
A reticulocyte (re-TIK-u-lo-site) count measures the
number of young red blood cells in your blood. The test shows whether your bone
marrow is making red blood cells at the correct rate. People who have
pernicious anemia have low reticulocyte counts.
Serum folate, iron, and iron-binding capacity tests
also can help show whether you have pernicious anemia or another type of
anemia.
Your doctor may recommend other blood tests to
check:
- Your vitamin B12 blood level. A low vitamin B12
level indicates pernicious anemia.
- Your homocysteine and methylmalonic acid (MMA)
levels. High levels of these substances in your body are a sign of pernicious
anemia.
- For intrinsic factor antibodies and parietal cell
antibodies. These antibodies also are a sign of pernicious anemia.
Bone Marrow Tests
Bone
marrow tests can show whether your bone marrow is healthy and making enough
red blood cells. The two bone marrow tests are aspiration (as-pi-RA-shun) and
biopsy.
For aspiration, your doctor removes a small amount
of fluid bone marrow through a needle. For a biopsy, your doctor removes a
small amount of bone marrow tissue through a larger needle. The samples are
then examined under a microscope.
In pernicious anemia, the bone marrow cells that
turn into blood cells are larger than normal (macrocystic).
How Is Pernicious Anemia Treated?
Doctors treat pernicious anemia by replacing the
missing vitamin B12 in your body. People who have pernicious anemia may need
lifelong treatment.
Goals of Treatment
The goals of treating pernicious anemia include:
- Preventing or treating the
anemia
and its signs and symptoms
- Preventing or controlling complications, such as
heart and nerve damage
- Treating the cause of the pernicious anemia (if
one can be found)
Specific Types of Treatment
Pernicious anemia usually is easy to treat with
vitamin B12 shots or pills.
If you have severe pernicious anemia, your doctor
may recommend shots first. Shots usually are given in a muscle every day or
every week until the level of vitamin B12 in your blood improves. After your
vitamin B12 blood level returns to normal, you may get a shot only once a
month.
For less severe pernicious anemia, your doctor may
recommend large doses of vitamin B12 pills. A vitamin B12 nose gel and spray
also are available. These products may be useful for people who have trouble
swallowing pills, such as older people who have had strokes.
Your signs and symptoms may begin to improve within
a few days after the start of treatment. Your doctor may advise you to limit
your physical activity until your condition improves.
If you have pernicious anemia due to a condition or
factor other than lack of intrinsic factor, you may get treatment for the cause
(if it can be found).
For example, medicines may be used to treat
conditions that prevent your body from absorbing vitamin B12. If medicines are
the cause of your pernicious anemia, your doctor may change the type or dose of
medicine you take. Infants of strict vegetarian mothers may be given vitamin
B12 supplements from birth.
How Can Pernicious Anemia Be Prevented?
You can't prevent pernicious anemia due to a lack of
intrinsic factor. Without intrinsic factor you won't be able to absorb vitamin
B12 and will develop pernicious anemia.
Although uncommon, some people develop pernicious
anemia because they don't get enough vitamin B12 in their diets. You can take
steps to prevent pernicious anemia due to dietary factors.
Eating foods high in vitamin B12 can help prevent
low vitamin B12 levels. Good food sources of vitamin B12 include:
- Meats such as beef, liver, and poultry
- Fish and shellfish
- Egg and dairy products, such as milk, yogurt, and
cheese
- Breakfast cereals and other fortified foods that
have vitamin B12 added
Vitamin B12 also is found in multivitamins and in
B-complex vitamin supplements. Doctors may recommend supplements for people at
risk for vitamin B12 deficiency, such as strict vegetarians or people who have
had stomach surgery.
Older adults may have trouble absorbing vitamin B12.
Thus, doctors may recommend that older adults eat foods that are fortified with
vitamin B12 or take vitamin B12 supplements.
Living With Pernicious Anemia
With proper treatment, people who have pernicious
anemia can recover, feel well, and live normal lives.
If you have complications of pernicious anemia, such
as nerve damage, early treatment may help reverse the damage.
Ongoing Care
If you have pernicious anemia, you may need lifelong
treatment with vitamin B12. See your doctor regularly for checkups and ongoing
treatment. Take vitamin B12 supplements as your doctor advises. This may help
prevent symptoms and complications.
During your followup visits, your doctor may check
for signs of vitamin B12 deficiency. He or she also may adjust your treatment
as needed.
If you have pernicious anemia, you're at higher risk
for stomach cancer. See your doctor regularly so he or she can check for this
complication.
Also, tell your family members, especially your
children and brothers and sisters, that you have pernicious anemia. Pernicious
anemia can run in families, so they may be more likely to develop the
condition.
Key Points
- Pernicious anemia is a condition in which the
body can't make enough healthy red blood cells because it doesn't have enough
vitamin B12.
- People who have pernicious anemia can't absorb
enough vitamin B12 due to a lack of intrinsic factor, a protein made in the
stomach. This leads to vitamin B12 deficiency. In people who have pernicious
anemia, the cells that make intrinsic factor are destroyed.
- Other conditions and factors also can cause
vitamin B12 deficiency. Examples include infections, surgery, medicines, and
diet. Technically, the term “pernicious anemia” refers to vitamin B12
deficiency due to a lack of intrinsic factor. Often, vitamin B12 deficiency due
to other causes also is called pernicious anemia.
- Without enough red blood cells to carry oxygen to
your body, you may feel tired and weak. Severe or long-lasting pernicious
anemia can damage the heart, brain, and other organs in the body. The condition
also can cause other complications, such as nerve damage, neurological problems
(such as memory loss), and digestive tract problems.
- Pernicious anemia is more common in people of
Northern European and African descent. In the United States, older people are
at higher risk for the condition. Pernicious anemia also can occur in younger
people and other population groups.
- The signs and symptoms of pernicious anemia are
due to a lack of vitamin B12 (vitamin B12 deficiency). Without enough vitamin
B12, your body can't make enough healthy red blood cells. This causes
anemia.
- Some of the signs and symptoms of pernicious
anemia, such as fatigue (tiredness), shortness of breath, and dizziness, apply
to all types of anemia. Other signs and symptoms, such as muscle weakness,
memory loss, and nausea (feeling sick to your stomach), are specific to a lack
of vitamin B12.
- Your doctor will diagnose pernicious anemia based
on your medical and family histories, a physical exam, and the results from
tests. Your doctor will want to find out whether the condition is due to a lack
of intrinsic factor or another cause.
- Doctors treat pernicious anemia by replacing the
missing vitamin B12 in your body. This is done using vitamin B12 pills or
shots. People who have pernicious anemia may need lifelong treatment. If your
doctor can find the cause of your pernicious anemia, you may get treatment for
that problem.
- You can't prevent pernicious anemia that's due to
a lack of intrinsic factor. However, if you have pernicious anemia because of
dietary factors, you can take steps to prevent it. Eating foods high in vitamin
B12 can help prevent low vitamin B12 levels. Your doctor also may advise taking
vitamin B12 supplements.
- With proper treatment, people who have pernicious
anemia can recover, feel well, and live normal lives. See your doctor regularly
for checkups and ongoing treatment. Take vitamin B12 supplements as your doctor
advises. This may help prevent anemia symptoms and complications.
- If you have pernicious anemia, tell your family
members. Pernicious anemia can run in families, so they may be more likely to
develop the condition.
Links to Other Information About Pernicious
Anemia
NHLBI Resources
Non-NHLBI Resources
Clinical Trials
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