Pernicious Anemia: Signs, Symptoms, Causes, Risks, Diagnosis, Treatment, Complications and Outlook

Illustration of pernicious anemia


The blood is an important part of the body because it’s responsible for making sure the needed oxygen and nutrients are distributed throughout the body. Just like any part of the body, some diseases can affect the blood and its numerous contents.

One of the conditions that can affect the blood is anemia. Anemia is a health condition wherein the red blood cell count is lower than normal, this includes the hemoglobin, which is responsible for distributing oxygen to the different parts of the body. This condition is caused by the decrease in the production of red blood cells or a raise in their loss due to bleeding. Moreover, the depletion of red blood cells and hemoglobin may be caused by their destruction due to an underlying medical condition.

Pernicious anemia is a rare blood disorder wherein there is the inability of the body to appropriately use vitamin B12, which is important for the production and development of red blood cells. One of the most common causes of this deficiency is the lack of intrinsic factor, a gastric protein that helps in the absorption of vitamin B12.

This type of anemia is an autoimmune condition that affects the stomach. An autoimmune disease means that the body’s immune system attacks the healthy cells because they regard them as foreign bodies.

2Signs and Symptoms (Mental and Physical)

The signs and symptoms of pernicious anemia include:

Mental Signs & Symptoms – The cognitive symptoms of pernicious anemia are harder to explain that the physical symptoms. The most common cognitive signs and symptoms include:

  • The “Fogs” – This is the most common complaint of patients who have pernicious anemia. The patients find it hard to define what they experience when they have the “fogs”. However, most of them report feelings of lack of clarity in things they experience and lack of focus in activities, both at work and at school.
  • Irritability, impatience and mood swings – People with pernicious anemia commonly experience these symptoms. These also have the greatest impact on personal relationships.
  • Less common mental symptoms – The less common mental symptoms include the inability to cope with work, depression, and pica.

Physical Signs & Symptoms

  • Strange Tiredness (lethargy, exhaustion, weariness, and fatigue)
  • Shortness of breath
  • Waking up tired
  • Inflamed tongue
  • Bloated feeling
  • Pale and yellow-tinged skin
  • Brittle nails
  • Feeling of pins and needles at the tips of fingers and feet
  • Less common physical symptoms like unusual gait, unsteadiness and the burning feeling in the feet and legs.


The exact cause of pernicious anemia is unclear. However, experts regard this condition as an autoimmune disease. Autoimmunity means that the body’s immune system is attacking the healthy cells in the body because the immune system thinks these cells are harmful to the body.

Lack of intrinsic factor (IF)

In the stomach, the vitamin B12 is combined with a protein called intrinsic factor. The mixture of these two substances is the one absorbed in the body. When a person has pernicious anemia, the immune system attacks the cells in the stomach that produce the intrinsic factor, leading to the inability to absorb vitamin B12 from food.

Lack of vitamin B12

Some individuals acquire pernicious anemia because they do not have vitamin B12 in their diets. Vitamin B12 plays a pivotal role in the production of red blood cells. Vitamin B12 is mainly found in:

  • Meats like liver, poultry, beef and fish
  • Shellfish
  • Eggs
  • Dairy products like milk, yogurt, and cheese
  • Fortified soy, nut, and rice milk
  • Breakfast cereals fortified with vitamin B12
  • Nutritional supplements


If a person has insufficient vitamin B12, the body will produce large red blood cells called macrocytes. These abnormal red blood cells are large and because of their size, they might not be able to leave the bone marrow. As a result, the number of oxygen-carrying red blood cells decreases, leading to the weakness.

4Risk Factors for Pernicious Anemia

Some people are at a higher risk of developing pernicious anemia. Here are the factors that may increase the risk of this rare blood disorder.


The older a person is, the higher the risk of having pernicious anemia.


Women are at a higher risk of developing this type of anemia than men.


People who are vegetarian do not eat the right amounts of meat. As a result, they are at an increased risk of having vitamin B12 deficiency, which has been linked to pernicious anemia.


Many experts believe that pernicious anemia is hereditary. This means that if you have a family history of pernicious anemia, you are at a higher risk of developing the disease.

Other risk factors:

  • Had part of the stomach removed
  • Other autoimmune disorders
  • Intestinal diseases
  • Pregnant
  • Taking medicines like antibiotics and seizure drugs
  • Breakfast cereals fortified with vitamin B12
  • Nutritional supplements


Pernicious anemia is usually diagnosed through the symptoms the patient is feeling and some blood tests.

The doctor will first conduct a thorough physical examination and medical history interview to determine the risk factors linked to pernicious anemia. A series of laboratory examinations will be requested, including:

Complete Blood Count (CBC)

The first test requested by the doctor is usually the complete blood count to determine if the patient has pernicious anemia.

In pernicious anemia, the CBC will reveal:

  • Low hemoglobin count
  • The MCV or mean corpuscular volume, which is the size of RBCs, is increased.
  • The mean corpuscular hemoglobin (MCH) is elevated but the mean corpuscular hemoglobin concentration (MCHC) remains normal.
  • The number of neutrophils, a type of white blood cell, and the platelets are low.

Peripheral Blood Smear

The results of a blood smear will show the RBCs to have large and abnormally-oval shapes.

Other tests include:

  • Folic acid levels
  • Vitamin B12 levels
  • Methylmalonic acid (MMA) levels
  • Homocysteine
  • Antibodies against the intrinsic factor (IF)
  • Reticulocyte count
  • Bone marrow aspiration and biopsy

Distinction Between Vitamin B12 Deficiency vs. Pernicious Anemia

Pernicious anemia is not the same as vitamin B12 deficiency. Pernicious anemia is one form of B12 deficiency that comes from an autoimmune response against the body’s intrinsic factor. However, the other causes of this deficiency may have the same symptoms as pernicious anemia.


Just like any other autoimmune disease, there is no cure for pernicious anemia.
However, over the years, there have been therapies that emerged to help people with pernicious anemia survive.

Until the 1920s, people with this type of blood disorder died, often after years of suffering. Medical innovations paved the way to improve their quality of life. Today, doctors treat pernicious anemia by replacing the missing vitamin B12 in the body.

Mainly, the goals of the treatment are to treat the signs and symptoms of the disease, prevent complications and treat the underlying cause of the condition.

Vitamin B12 injections

Patients with severe pernicious anemia may receive the shots first. Vitamin B12 injections can be given daily or weekly, depending on the vitamin B12 levels. The injections are given until the levels reach normal or close to normal. After the levels return to normal, the patient may receive a shot per month.

Vitamin B12 oral supplements

Some patients may take regular doses of supplements instead of the injections as maintenance. The vitamin B12 pills are recommended for those with less severe pernicious anemia. However, these are given in large doses.

Other vitamin B12 forms

The doctor may recommend other forms of vitamin B12 supplementation like nose gel and spray, especially for those who had suffered a stroke and those with difficulty swallowing.

The signs and symptoms of pernicious anemia may improve after a few days of treatment. However, during the initial treatment, the doctor may recommend the patient to limit his or her physical activity until the condition improves.

If the pernicious anemia is caused by other factors like the lack of intrinsic factor, the underlying cause is treated first. For instance, the physician may prescribe drugs to treat the underlying condition that prevents the body from absorbing vitamin B12 from the diet.


The doctor may prescribe regular monitoring of the condition. This will help prevent the serious complications of pernicious anemia. One of the most serious complications of this rare blood disorder is gastric cancer.

Other complications linked to pernicious anemia include:

  • Nerve damage
  • Heart problems
  • Memory problems
  • Confusion
  • Neurological changes
  • Stomach cancer
  • Infertility
  • Neural tube defects in infants born to mothers with deficiency in vitamin B12
  • False Postive Pap Smear
  • Gastric Polyp
  • Gastric Carcinoid Tumor


A person with well-treated pernicious anemia can live a healthy and normal life.
However, early detection is vital. Those who are not diagnosed promptly may result in permanent neurological problem and damage, depression, memory loss, fatigue and other complications.

In severe cases, the complications may even lead to death. In fact, the term “pernicious” means “deadly”. Many individuals with the rare blood disorder require lifelong treatment and regular medical check-ups.

Detecting the symptoms of long-term damage caused by pernicious anemia is important. The symptoms include having a difficulty swallowing, an upset stomach, iron deficiency and weight loss. It’s important to have regular consultations with the doctor, especially when these symptoms emerge.

The early detection and treatment of pernicious anemia may help prevent future health problems and improve the quality of life of those who have the disorder.