Pernicious Anaemia

What Is Pernicious Anaemia?

Pernicious anaemia occurs when the body fails to produce enough vitamin B12, which in turn means the body’s red blood cell production is low. The condition is most commonly found in individuals who have health conditions that prevent them from taking in vitamin B12 through their diet.  

About anaemia

Anaemia is a common condition which occurs when there are low levels of red blood cells and haemoglobin (a protein found in red blood cells which transports oxygen around the body). As a result of this not enough oxygen is transported to the cells. The most obvious sign of anaemia is extreme tiredness.

About pernicious anaemia

Pernicious anaemia is the result of a shortage of vitamin B12. This deficiency prevents the blood cells from dividing normally and causes the red blood cells to be too large, which makes it difficult for them to move from the bone marrow. Vitamin B12 is found within the B vitamin group, along with other vitamins. B vitamins usually derive from animal-based products, including meat, poultry, eggs, fish and dairy products. Vitamin B12 is essential for healthy red blood cell production and effective nervous system functioning.

There are three main ways individuals can develop decreased levels of vitamin B12:

  • A lack of intrinsic factor: this is a protein which is found within the stomach and is responsible for absorbing vitamin B12. Specific cells within the stomach lining produce intrinsic factor, but in some individuals the cells can be destroyed either as an outcome of surgery on the stomach or an autoimmune condition. If the body is unable to produce the intrinsic factor it cannot absorb vitamin B12, which is the main source of vitamin B12 deficiency.
  • Diet: a diet lacking in vitamin B12 may include poor eating habits, strict vegetarianism or alcoholism.
  • Intestinal disorders: this may be the case if a disorder interferes with the body’s capacity to take in vitamin B12. Examples include Crohn’s disease and infections in the intestine.

This form of anaemia is called pernicious anaemia. This is because it often became fatal before the source of the disorder could be found and treatment made available. In modern times pernicious anaemia can be controlled effectively by taking vitamin B12 supplements or having injections. However, pernicious anaemia can be serious if left untreated and may result in irreparable harm to the body. The condition is most common among older adults.

Pernicious anaemia’s impact on the body

Individuals who suffer with pernicious anaemia typically experience tiredness and feel weak, because there is insufficient oxygen travelling around the body. If the condition is left untreated it can bring on serious harm to the nerves, heart and other organs in the body.

Effects on the heart: it takes extra effort for the heart to pump blood around the body in individuals who suffer with pernicious anaemia. The added stress can often be a source of heart murmurs, irregular heartbeat, rapid heart rate, enlarged heart and, in extreme cases, heart failure.

A shortage of vitamin B12 may also lead to heart problems because it contributes to increased levels of homocysteine. This is a chemical which can cause fatty deposits to collect in the blood vessels around the heart, thus increasing the chances of strokes and heart attacks.

Effects on the nerves: a shortage of vitamin B12 can contribute to impairment of the nerve cells, which may cause tingling and lack of feeling. This is especially in the feet and hands and it can also cause problems with balance and walking. A shortage of vitamin B12 can also affect the senses and may reduce smell, taste and sometimes vision, and it may in addition cause mental problems, such as confusion.

Effects on the digestive system: a shortage of vitamin B12 often affects digestion. A deficiency can alter the tongue’s surface and cause the stomach lining to become thinner. The changes within the stomach can also elevate the chance of stomach cancer.


If diagnosed early and treated effectively pernicious anaemia can be managed easily. However, if left untreated it can be very serious and may result in permanent harm to the nerves, heart and amplify the chances of stomach cancer. If the condition is treated and managed effectively, there is no reason why people should not live a long and healthy life.

Pernicious anaemia is also known as:

  • Congenital pernicious anaemia.
  • Vitamin B12 deficiency anaemia.
  • Megaloblastic anaemia.
  • Combined systems disease.

What are the causes of pernicious anaemia?

Main causes

Pernicious anaemia is mainly the result of a deficiency in vitamin B12. The chief cause for a shortage of vitamin B12 is the destruction of parietal cells found in the stomach, which are responsible for producing the protein, intrinsic factor. The parietal cells can be destroyed by stomach surgery or if the immune system is attacking the cells, which is caused by an autoimmune condition such as Crohn’s disease. Doctors do not fully understand why the immune system creates antibodies to attack the parietal cells. Once the cells have been attacked the lining of the stomach shrinks and the cells stop producing intrinsic factors, which contributes to a deficiency in vitamin B12.

The parietal cells are also susceptible to damage via surgery on the stomach, or lost as a consequence of surgery to remove the stomach lining or a section of the stomach, which happens during weight loss surgery.

A rare hereditary disorder also exists which prevents children from being able to make intrinsic factor and causes vitamin B12 deficiency.

Other causes

Rarer sources of pernicious anaemia also include:

  • Taking certain medications.
  • A diet deficient in vitamin B12.
  • Problems or conditions affecting the intestines.

Shortage of vitamin B12 found in the diet

It is possible to develop pernicious anaemia by not taking in enough vitamin B12 from your diet. If this is the case the condition will develop gradually, since the body has vitamin B12 stores which can be used for a period of time.

Animal-based products usually provide a good supply of vitamin B12, so individuals who follow a strictly vegetarian diet may heighten their risk of pernicious anaemia. This is particularly the case if they do not include dairy products, eggs or fish in their diet. If an individual has a strict diet that puts them at risk of pernicious anaemia, they may be advised to add vitamin B12 supplements to their food intake.

Certain individuals develop pernicious anaemia as a consequence of having a poor diet, which may be a result of ageing and struggling to follow a healthy diet, alcoholism or choosing poor food options.

Small intestine disorders

Certain intestinal conditions can affect the way the body takes in vitamin B12, including:

  • Crohn’s disease; a condition which causes an inflammation of the bowel.
  • Coeliac disease; a condition involving an inability to tolerate gluten.
  • Bacterial infections.
  • A lack of stomach acid.


Using certain types of medication on a long-term basis may cause pernicious anaemia. Examples include medication used to reduce stomach acid and those used to control diabetes.

Who is most at risk of pernicious anaemia?

Populations affected

Pernicious anaemia can affect people from all different races, though it tends to be more common in people with Northern European and African heritage. Pernicious anaemia affects males and females equally and it can affect people of all ages, but it is commonly found in older adults and rarely affects children.

Main risk factors

Risk factors include:

  • Pernicious anaemia within the family history.
  • Thyroid problems.
  • Diabetes.
  • An intestinal condition which affects how the body absorbs vitamin B12.
  • A diet lacking in vitamin B12.

What are the symptoms and signs of pernicious anaemia?

The most common signs of pernicious anaemia include:

  • Feeling tired.
  • Weakness.
  • A bright red and smooth tongue.

Other symptoms include:

  • Numbness and tingling caused by nerve damage (usually in the feet and hands).
  • Pale or yellow skin.
  • A raised temperature.
  • Dizziness.

Symptoms tend to develop gradually and if the condition is left untreated it can cause harm to the nerves and heart. Pernicious anaemia can also cause mental problems, such as confusion and memory loss, which tends to affect older people.


Complications can include harm to the nerves, heart and the brain. The digestive tract can also be affected and the chances of stomach cancer may be increased. Complications can be caused by anaemia and a shortage of vitamin B12.

Heart: signs of heart conditions include heart murmurs, chest pain, shortness of breath, an irregular heartbeat and heart failure.

Nervous system and the brain: symptoms include numbness and tingling in the feet and hands, difficulty walking, memory loss, a lack of balance, confusion and a reduction of the senses (smell, taste and vision).

Digestive tract: symptoms can develop along the digestive tract, from a smooth, red tongue, bleeding gums and mouth sores to nausea and sickness, an enlarged liver, heartburn, diarrhoea and constipation. Individuals suffering with pernicious anaemia may also experience a decreased appetite and subsequent weight loss.

How is a pernicious anaemia diagnosis made?

A diagnosis is based on physical examination, medical history and further diagnostic tests. Doctors can use tests to determine the cause of the condition, distinguish between certain forms of anaemia and establish the severity of the condition. In many cases anaemia only causes mild symptoms and it often becomes apparent during routine tests or tests for other health conditions.

Specialists involved

Your family doctor will usually be the first port of call and they will refer you to a specialist if they think you have pernicious anaemia. Specialists that may be involved in your care include:

  • A haematologist (a specialist in blood disorders).
  • A neurologist (a specialist in the nervous system).
  • A cardiologist (a heart specialist).
  • A gastroenterologist (a specialist in digestive tract disorders).

Medical history

Your GP will ask you questions about your medical history, which will include enquiries about health problems, underlying conditions, problems you have had in the past and what symptoms (if any) you are experiencing. The doctor will then most likely ask if other members of your family have suffered with anaemia, diabetes or conditions affecting the immune system. You will also be asked if you have ever had surgery and if you are taking medication or have recently stopped taking medication. Questions on your diet are also likely to be included.

Physical examination

During a physical examination the doctor will check for these symptoms:

  • Paleness.
  • Yellow skin.
  • A smooth, red tongue.
  • A rapid heartbeat.
  • A heart murmur.
  • An enlarged liver.

Diagnostic procedures and tests

Your GP will order diagnostic tests to determine the form of anaemia, the severity of the condition and the cause. These tests may include:

Complete blood count: also known as a full blood count this is generally the primary test to be carried out if anaemia is suspected. The complete blood count shows the haemoglobin level and the haematocrit level. Haemoglobin is an iron-rich protein found in red blood cells and is responsible for transporting oxygen around the body. The haematocrit level shows the quantity of blood containing red blood cells. If the haemoglobin and haematocrit levels are low this indicates anaemia.

The complete blood count checks:

  • Red blood cell numbers: if the number is low this indicates anaemia.
  • White blood cell numbers: help to fight infections and illnesses.
  • Platelet numbers: platelets are involved in the blood clotting process.
  • The size of the red blood cells: the average cell volume test measures the dimensions of the red blood cells. With this particular condition the red blood cells are bigger than normal (known as macrocytosis).

Tests to measure vitamin B12 levels

  • Vitamin B12: the sum of vitamin B12 in the blood can be normal, even if the quantity of vitamin B12 is low.
  • Folate (folic acid): folate is another type of B vitamin, which may be deficient when there is a shortage of vitamin B12. A lack of folate can cause anaemia.
  • Homocysteine: levels of homocysteine are high when levels of vitamin B12 or folate are low.
  • Methylmalonic acid: levels of methylmalonic acid are higher than normal in individuals with pernicious anaemia due to low levels of vitamin B12. Methylmalonic acid levels can be checked by a urine test.

Other blood test measurements

  • The occurrence of parietal cells and intrinsic factor antibodies. Intrinsic factor is the protein that enables the body’s assimilation of vitamin B12 from food. If antibodies are present this may mean that the body is attacking the parietal cells which produce intrinsic factor.
  • The degrees of bilirubin, cholesterol and potassium.
  • Serum iron and iron binding capacity.
  • The quantity of reticulocytes (immature red blood cells). This test is designed to measure the rate of red blood production by the bone marrow. If the test result is low this may indicate that the bone marrow isn’t producing a sufficient amount of red blood cells.

The Schilling test can also be used and calculates the efficiency of the body’s vitamin B12 absorption capacities – but doctors do not commonly use this test today. Bone marrow tests can also be required. The doctor will take a sample (biopsy) of the one marrow or remove bone marrow fluid by means of a procedure called aspiration, to check that the bone marrow is functioning properly.

What are the treatments for pernicious anaemia?

Bolstering the sum of vitamin B12 found in the body treats pernicious anaemia, but in most cases the condition requires lifelong treatment. If pernicious anaemia is left untreated it can be serious and cause permanent or long lasting harm to the body.

Aims of treatment

The aims of treatment include:

  • Stopping anaemia and the associated symptoms by increasing the sum of vitamin B12 found in the body.
  • Preventing complications, including harm to the nerves, heart and brain.
  • Providing continuous care and support to enable patients to live a normal, healthy life.
  • Treating the underlying reason for anaemia (if this is possible).

Specific forms of treatment

In most cases pernicious anaemia is simple to treat using vitamin B12 supplements or injections. Symptoms can start to improve very quickly, in the region of 4 days after starting treatment.

  • Vitamin B12 injections: injections may initially be given daily, weekly and then monthly once vitamin B12 levels have increased. Some people have a combination of pills and injections.
  • Vitamin B12 tablets: many people can be successfully treated using vitamin B12 supplements. However, high doses are required because the body only absorbs a tiny sum of vitamin B12.

Vitamin B12 may also be administered via nasal sprays and gels.

Treatment for the fundamental source of pernicious anaemia may also be required, which can involve taking antibiotics for a stomach infection or undergoing surgery for an intestinal condition. If a deficiency in vitamin B12 is the result of a deprived diet, making changes to this may help to reduce symptoms. Doctors may advise restricting physical activity pending improvement of symptoms.

Preventing pernicious anaemia

It is not possible to entirely stop the condition when it is the result of an autoimmune condition. The decrease in the numbers of parietal cells that produce intrinsic factor is the most frequent reason for pernicious anaemia.

It is uncommon for pernicious anaemia to be caused by a shortage of vitamin B12 in the diet. However, it is possible and eating a healthy, balanced diet can help to reduce the chances of pernicious anaemia. Good sources include:

  • Eggs.
  • Fish.
  • Meat.
  • Poultry.
  • Dairy products.
  • Leafy green vegetables (such as spinach and watercress).
  • Fortified cereals.
  • Beans, pulses and lentils.
  • Nuts.
  • Oranges.

Doctors may advise individuals who have a higher risk of pernicious anaemia (including individuals with a very strict vegetarian or vegan diet) to take vitamin supplements.

Life with pernicious anaemia

Individuals can live a healthy, normal life if their condition is well managed. However, they must take care to follow the treatment advice and see their care team on a regular basis. If complications develop it is often possible to treat these, but it is important that individuals see their doctor if they notice changes in their health or develop symptoms, rather than ignoring them.

All patients with pernicious anaemia will be monitored closely and adjustments to treatment will be made as and when necessary.

Doctors can also offer advice on diet to ensure patients are taking in enough vitamin B12 from the foods they eat.


If the condition is diagnosed in your family it is advised that other family members are tested, as the condition tends to run in families.

Key facts

  • Pernicious anaemia is a form of anaemia caused by a deficiency in vitamin B12. It is also known as vitamin B12 deficiency anaemia.
  • Vitamin B12 is needed to enable the body to produce red blood cells and keep the nerves healthy. Vitamin B12 is included in meat, eggs, fish and dairy products.
  • The main source of pernicious anaemia is a decline in parietal cells, which produce a protein called intrinsic factor that enables the body to take in vitamin B12. Parietal cells can be destroyed by the body because of an abnormal immune system response.
  • Pernicious anaemia can become serious if left untreated and can cause long lasting or permanent harm to the nerves and heart. It may also elevate the chances of stomach cancer.
  • Normal signs of the condition are tiredness, weakness and a smooth, red tongue.
  • A pernicious anaemia diagnosis is made using a combination of tests, including family and medical history, physical examinations, blood tests and additional tests, such as bone marrow tests.
  • The condition is typically easy to manage and the main treatments are vitamin B12 supplements and injections.
  • Complications are often reversible if treated swiftly.
  • It is not possible to stop pernicious anaemia brought on by the destruction of the parietal cells, which is a result of an abnormal immune system response.
  • Eating a healthy, balanced diet containing foods with vitamin B12 can help to reduce the chances of a deficiency in vitamin B12. Examples include meat, eggs, fish, dairy products and leafy green vegetables.
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