What Is Pernicious Anemia?
Pernicious anemia (per-NISH-us uh-NEE-me-uh) is a
condition in which the body does not make enough red blood cells due to a lack
of vitamin B12 in the body. It usually occurs in people whose bodies have lost
the ability to absorb vitamin B12 from food.
Pernicious anemia is one of many different types of
anemia. Having anemia means you do
not have enough healthy red blood cells. When a person has anemia, the blood
cannot carry enough oxygen to the cells of the body. The most common symptom of
anemia is feeling tired.
In pernicious anemia, the blood cells do not divide
normally and are too large. They have trouble getting out of the bone marrow.
The problem is due to a lack of vitamin B12 in the body. Vitamin B12 is one of
the B vitamins; B vitamins are found in animal foods such as meat, fish, eggs,
milk, and other dairy products. Vitamin B12 is necessary for the body to make
red blood cells. It is also needed for the normal working of the nervous
People can develop low levels of this important
vitamin in three main ways:
- From the lack of a protein in the stomach that
helps the body absorb vitamin B12. The protein is called intrinsic
(in-TRIN-sik) factor. Intrinsic factor is made by special cells in the lining
of the stomach. In some people, these cells are destroyed by the bodys
immune system or as a result of stomach surgery. When this happens, intrinsic
factor is not produced and vitamin B12 cannot be absorbed. This is the most
common cause of vitamin B12 deficiency.
- From not getting enough vitamin B12 in the diet.
This can be the result of eating a strict vegetarian diet or a poor diet due to
factors such as aging or alcoholism.
- From certain intestinal disorders that interfere
with the absorption of vitamin B12, such as
Crohns disease and intestinal infections.
The condition was named pernicious
anemia because it was often fatal in the years before the cause was discovered
to be a lack of vitamin B12, and no specific treatments were available. Now it
is easy to treat with vitamin B12 pills or injections. Pernicious anemia can be
severe if it goes on for a long time without being treated. If it is not
treated, it can cause permanent damage to the body. Pernicious anemia is
especially common in older adults.
Effects of Pernicious Anemia on the Body
People who have pernicious anemia often feel tired
and weak because the body is not getting enough oxygen. Over time, if
untreated, this disease can cause serious problems for the heart, nerves, and
other parts of the body.
Heart. In people with anemia, the
heart has to work harder to pump blood to get enough oxygen to the bodys
organs and tissues. This stress on the heart can cause
murmurs (an extra or unusual sound heard during the heartbeat), fast or
irregular heartbeats, an enlarged heart, or even
A lack of vitamin B12 or folic acid (folate) can
cause extra problems for the heart because it raises the level in the body of a
chemical called homocysteine (ho-mo-SIS-teen). High levels of homocysteine add
to the buildup of fatty deposits in blood vessels, which in turn can lead to
Nerves. A lack of vitamin B12 can
damage nerve cells and cause problems such as tingling and numbness in hands
and feet and problems with walking and balance. A vitamin B12 deficiency can
cause changes in taste, smell, and vision. Finally, it can cause mental
changes, including memory loss and confusion.
Digestive tract. A lack of vitamin
B12 may change the surface of the tongue and shrink or thin the stomach lining.
Any changes that occur in the stomach can put a person at risk for stomach
Pernicious anemia is usually easy to treat with
vitamin B12 pills or shots, although some people develop permanent nerve damage
before they find out they have the disease and get treatment. Since pernicious
anemia does increase the risk of developing stomach cancer, doctors may do
periodic cancer tests to check for it. Overall, however, people with pernicious
anemia who get proper lifelong treatment can have a normal lifespan.
Other Names for Pernicious Anemia
- Megaloblastic anemia
- Vitamin B12 deficiency anemia
- Combined systems disease
- Congenital pernicious anemia
What Causes Pernicious Anemia?
Pernicious anemia is caused by a lack of vitamin B12
in the body. The main reason for the vitamin B12 deficiency is the loss of
parietal (pa-RI-e-tal) cells in the lining of the stomach. These cells make
intrinsic factor, which helps the body absorb vitamin B12 in the small
intestine. In some people, the bodys immune system may attack and destroy
the parietal cells. Doctors dont know exactly why or how this happens, or
if the immune system produces antibodies in reaction to normally aging or dying
As a result of this immune system attack, the
stomach lining shrinks, and the parietal cells in the lining of the stomach
disappear. The stomach stops producing intrinsic factor. Over time, vitamin B12
Loss of intrinsic factor can also be due to removal
of the stomach lining in various kinds of stomach surgery. This surgery
includes removal of all or part of the stomach as well as stomach surgery for
There is also a rare inherited disorder in which
children are born without the ability to produce intrinsic factor.
Less common causes of pernicious anemia include a
diet low in vitamin B12, intestinal problems, and certain medicines.
Lack of Vitamin B12 in the Diet
People can develop pernicious anemia if they
dont get enough vitamin B12 in the foods that they eat. This condition
takes many years to develop because it takes time to use up the vitamin B12
already stored in the body.
Some people who are strict vegetarians can develop
pernicious anemia, especially if they do not eat meat, poultry, fish, eggs, or
dairy productsthe best food sources of vitamin B12. Breastfed
infants of strict vegetarian mothers can develop anemia in a short time because
they dont have enough vitamin B12 stored in their bodies. They can be
given vitamin B12 supplements to prevent this type of anemia.
Some people develop pernicious anemia because of a
poor diet due to conditions such as alcoholism or aging.
Disorders of the Small Intestine
Some intestinal problems can cause poor absorption
of vitamin B12. These problems include:
- An infection caused by parasites or an overgrowth
of bacteria in the intestine
- Celiac disease (also known as sprue), a genetic disorder that
makes a person unable to tolerate gluten
- Crohns disease, an inflammatory bowel disease
- Not enough stomach acid to digest fooda
problem that can occur in older adults
Long-term use of certain medicines may lead to
pernicious anemia. Examples of these are medicines that reduce acid in the
stomach and certain diabetes medicines (such as metformin, phenformin, and
Who Is At Risk for Pernicious Anemia
People of all races can develop pernicious anemia.
However, people of northern European or African descent have a higher risk than
other races and ethnic groups.
Men and women in the United States are equally
likely to develop the disease. It is more common in older adults than younger
people, and it is rare in children.
Major Risk Factors
A persons chances of developing pernicious
anemia may be higher if he or she has:
- A family history of pernicious anemia (blood
relatives with the disease)
- A disorder such as
diabetes or a thyroid problem
- An intestinal disorder that keeps the body from
absorbing vitamin B12 well
Pernicious anemia is more likely to develop in
people who do not eat foods high in vitamin B12 for long periods of time. This
includes some vegetarians, elderly people, and people with alcoholism.
What Are the Signs and Symptoms of Pernicious
Major Signs and Symptoms
Major signs and symptoms of pernicious anemia are
feeling tired and weak and having a bright red, smooth tongue. Common symptoms
of nerve damage caused by this disease are tingling and numbness in the hands
Symptoms most often develop slowly over time if the
disease is not treated. Some people may experience mental changes and nerve
problems before blood tests show that they have anemia. This is more likely to
happen in older adults than in younger people.
Other Signs and Symptoms
Other signs and symptoms of pernicious anemia may
include pale or yellowish skin, a low-grade fever, and dizziness when standing
up. Infants with the condition may show unusual movements or a delayed
development and failure to thrive.
Signs and Symptoms of Complications Associated With
Complications seen with pernicious anemia can
involve the heart, nerves and brain, and digestive tract. Some of the
complications are due to the anemia; others are the effect of a low vitamin B12
level on parts of the body.
Signs and symptoms of heart problems may include
shortness of breath and chest pain.
murmurs, a rapid heart rate, and
failure can develop.
Nerves and Brain
In addition to tingling or numbness in the hands and
feet, signs and symptoms of problems with the nerves may include difficulty
walking, unsteady movement, and loss of balance. There can be changes in
vision, taste, and smell. Memory loss, confusion, depression, and even
psychosis can develop.
Signs and symptoms of untreated pernicious anemia
can occur all along the digestive track. They can start with a bright red,
smooth tongue and may include mouth sores or bleeding gums. The liver could be
enlarged. Nausea and vomiting may occur, along with a sense of fullness, gas,
or heartburn. Changes in bowel habits could include constipation or diarrhea. A
person might have a loss of appetite or weight loss.
How Is Pernicious Anemia Diagnosed?
Pernicious anemia is diagnosed using a persons
medical history, physical exam, and tests that can determine the type and cause
of anemia. A doctor can use these methods to find out how severe the problem
is, its cause, and the appropriate treatment. Mild to moderate anemia may have
no signs or symptoms. In fact, anemia is often discovered unexpectedly on
Primary care doctors, such as a family doctor, often
diagnose and treat pernicious anemia. Other kinds of doctors may also be
- A neurologist (nervous system specialist)
- A cardiologist (heart specialist)
- A hematologist (blood disease specialist)
- A gastroenterologist (digestive tract disease
Medical and Family History
Your doctor may ask detailed questions about many
symptoms, including feeling tired and weak and others listed in the section
What Are the Signs and Symptoms of Pernicious
Anemia? The doctor may ask about any personal or family history of
diabetes, or diseases of the immune system. You may be asked
about any surgery you have had, especially stomach surgery. The doctor may also
ask you about your diet and about the medicines you are taking.
A physical exam may include:
- Checking for pale or yellowish skin and a red,
- Listening to the heart to check for a rapid
- Feeling the abdomen to check the size of the
Your doctor will also order a number of tests or
procedures to be sure about the type of anemia you have and how severe it
Diagnostic Tests and Procedures
Complete Blood Count
Usually, the first test used to diagnose anemia is a
complete blood count (CBC). The CBC tells a number of things about a
persons blood, including:
- The hemoglobin level. Hemoglobin is the iron-rich
protein in red blood cells that carries oxygen through the body. A low
hemoglobin level means a person has anemia.
- The hematocrit (hee-MAT-oh-crit) level. The
hematocrit level measures how much of the blood is made up of red blood cells.
Low hematocrit is another sign of anemia.
The CBC also checks:
- The number of red blood cells. Too few red blood
cells means a person has anemia. A low number of red blood cells is usually
seen with either a low hemoglobin or a low hematocrit level, or both.
- The number of white blood cells. White blood
cells are involved in fighting infection.
- The number of platelets in the blood. Platelets
are small cells that are involved in blood clotting.
- Red blood cell size. The mean cell volume is the
name of a test that measures the average size (volume) of red blood cells. In
pernicious anemia, the red blood cells are usually larger than normal. This is
called macrocytosis (MAK-ro-si-TO-sis).
Tests To Check the Vitamin B12 Level
- Vitamin B12. The level of vitamin B12 in the
bloodstream may be normal or borderline even when the total amount of B12 in
the body is low.
- Folic acid (folate). This is another B vitamin
that can be low when the B12 level is low. A lack of folic acid can also cause
- Homocysteine. Homocysteine is high in anemia due
to the lack of vitamin B12 or folic acid. Folate deficiency is more common
because this vitamin is used up more quickly and the dietary need is greater.
In this case, the bloods B12 level can be normal.
- Methylmalonic (METH-il-ma-LON-ik) acid. The level
of methylmalonic acid is high in anemia due to a lack of vitamin B12 or folic
acid. Methylmalonic acid can also be checked with a urine test.
Other Blood Tests
Other blood tests check for:
- The presence of intrinsic factor antibodies and
parietal cell antibodies. These antibodies in the blood may mean that they are
destroying the intrinsic factor or parietal cells.
- Levels of bilirubin, potassium, or cholesterol in
- Serum iron and iron binding capacity.
- The number of reticulocytes (re-TIK-u-lo-sites).
Reticulocytes are young, red blood cells. The reticulocyte test is used to see
if the bone marrow is producing red blood cells at the proper rate. A lower
than average number of reticulocytes can mean that the bone marrow is not
making enough red blood cells. The reticulocyte number is low in people with
The Schilling test is a urine test that measures how
well the body absorbs vitamin B12. It is not used as much now as it was in the
Bone Marrow Tests
In some cases, a doctor may want to do a bone marrow
biopsy or aspiration. A bone marrow biopsy is a minor surgical procedure to
remove a small amount of bone marrow tissue. In a bone marrow aspiration, the
doctor removes a small amount of bone marrow fluid through a needle. Bone
marrow biopsy or aspiration tests whether the bone marrow is healthy and can
show whether the bone marrow is making enough blood cells.
How Is Pernicious Anemia Treated?
Doctors treat pernicious anemia by replacing the
missing vitamin B12 in the body. People who have pernicious anemia need
treatment, usually for the rest of their lives. Without treatment, pernicious
anemia can cause serious problems and can even be fatal.
Goals of Treatment
The goals of treating pernicious anemia are to:
- Stop the anemia and symptoms through vitamin B12
- Prevent complications, such as heart or nerve
- Provide ongoing followup to make sure that the
treatment is working
- Treat the underlying cause, if one can be
Specific Types of Treatment
Fortunately, pernicious anemia is usually easy to
treat with either vitamin shots (injections) or pills. Symptoms may begin to
improve within a few days after the start of treatment.
- Vitamin B12 shots. People with pernicious anemia
may get daily or weekly shots at first, then one shot every month. Some people
get vitamin B12 shots and also take vitamin B12 pills.
- Vitamin B12 pills. Many people with pernicious
anemia can be treated successfully with vitamin B12 pills. Often, the pills
work as well as the shots. Because only a small amount of vitamin B12 is
absorbed by the body, high doses are given.
Vitamin B12 can also be given in a gel or spray for
Treatment for the underlying causes of vitamin B12
deficiency may be needed. To help the body absorb vitamin B12, for example, a
person might need antibiotics to treat stomach infections or surgery to treat
intestinal problems. If the vitamin B12 level is due to a poor diet, then a
person can learn how to correct the diet.
The doctor may also recommend limiting physical
activity until anemia symptoms have improved.
How Can Pernicious Anemia Be Prevented?
Doctors do not know how to prevent pernicious anemia
that occurs from the immune system destroying parietal cells in the stomach.
The most common cause of pernicious anemia is the loss of stomach cells that
make intrinsic factor.
Pernicious anemia due to a diet low in vitamin B12
is not common. But some people who are strict vegetarians or who have a poor
diet for a long time can develop this condition. Eating foods high in vitamin
B12 and folic acid can help prevent low vitamin B12 levels. Some of these foods
- Eggs, meat, poultry, or shellfish
- Milk, orange juice, or oranges
- Fortified cereals, wheat germ, rice, or
- Romaine lettuce, spinach, and other green leafy
- Sprouts, broccoli, asparagus
- Peas, peanuts, beans, lentils, soy beans, and
You can get a
Dietary Supplement Fact Sheet: Vitamin B12 from
the Office of Dietary Supplements, National Institutes of Health.
Vitamin B12 also can be found in multivitamins and
in B-complex vitamin supplements.
Doctors may recommend supplements for people at risk
of developing vitamin B12 deficiency, such as infants and children of strict
Living With Pernicious Anemia
People treated for pernicious anemia can recover,
feel well, and live normal lives, although they must be sure to receive enough
vitamin B12 throughout their lives. If a person has developed health problems
caused by pernicious anemia, such as nerve damage, treatment may reverse the
Ongoing Health Care Needs
People with pernicious anemia usually need to see a
doctor regularly for checkups and ongoing treatment with vitamin B12. If you
are being treated for pernicious anemia, you will need to take vitamin B12
supplements as directed by your doctor to prevent the return of symptoms.
Visits to the doctor will focus on monitoring for
signs of vitamin B12 deficiency in your body, making treatment changes as
needed, and checking for the possible development of stomach cancer.
Doctor visits will also focus on the foods that you
eat and whether you are eating enough foods that contain vitamin B12. A
pediatrician may prescribe vitamin B12 supplements for infants and children of
Continued treatment may be needed for any ongoing
problems due to nerve damage.
If you have been diagnosed with pernicious anemia,
you should tell your family members about the diseaseespecially your
children and your siblings. Because pernicious anemia runs in families, they
may be more likely to develop the disease.
- Pernicious anemia is a condition caused by too
little vitamin B12 in the body. It is also called vitamin B12 deficiency
- Vitamin B12 helps the body make healthy red blood
cells and helps keep nerve cells healthy. It is found in animal foods,
including meat, fish, eggs, milk, and other dairy products.
- The most common cause of pernicious anemia is the
loss of stomach cells that make intrinsic factor. Intrinsic factor helps the
body absorb vitamin B12 in the intestine. The loss of parietal cells may be due
to destruction by the bodys own immune system.
- Pernicious anemia can cause permanent damage to
nerves and other organs if it goes on for a long time without being treated. It
also raises the risk for developing stomach cancer.
- Common signs and symptoms of pernicious anemia
- Feeling tired and weak
- Tingling and numbness in hands and feet
- A bright red, smooth tongue
- Pernicious anemia is diagnosed using family
history and medical history, a physical exam, and diagnostic tests and
- Pernicious anemia is easy to treat with vitamin
B12 pills or shots as well as diet changes. Lifelong treatment is needed.
- Complications caused by untreated pernicious
anemia may be reversible with treatment.
- Doctors dont know how to prevent pernicious
anemia that is caused by the immune system destroying stomach cells.
- Eating foods high in vitamin B12 and folic acid
can help prevent vitamin B12 deficiency caused by a poor diet.
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