Vitamin B12 deficiency anemia
Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues. There are many types of anemia.
Anemia
Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues. Different type...
Read Article Now Book Mark ArticleVitamin B12 deficiency anemia is a low red blood cell count due to a lack (deficiency) of vitamin B12.
Vitamin B12
Vitamin B12 is a water-soluble vitamin. Water-soluble vitamins dissolve in water. After the body uses what it needs of these vitamins, leftover amo...
Read Article Now Book Mark ArticleCauses
Your body needs vitamin B12 to make red blood cells. In order to provide vitamin B12 to your cells:
- You must eat foods that contain vitamin B12, such as meat, poultry, shellfish, eggs, fortified breakfast cereals, and dairy products.
- Your body must absorb enough vitamin B12. A special protein, called intrinsic factor, helps your body do this efficiently. This protein is released by cells in the stomach.
Certain health conditions can make it difficult for your body to absorb enough vitamin B12. They include:
- Pernicious anemia, a condition that occurs when your body destroys cells in your stomach that make intrinsic factor, which may lead to vitamin B12 deficiency and anemia
Pernicious anemia
Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues. There are man...
Read Article Now Book Mark Article - Surgery that removes certain parts of your stomach or small intestine, such as some weight-loss surgeries
- Crohn disease, celiac disease, infection with the fish tapeworm, or other problems that make it difficult for your body to digest foods
Crohn disease
Crohn disease is a disease where parts of the digestive tract become inflamed. It most often involves the lower end of the small intestine and the be...
Read Article Now Book Mark ArticleCeliac disease
Celiac disease is an autoimmune condition that damages the lining of the small intestine. This damage comes from a reaction to eating gluten. This ...
Read Article Now Book Mark Article - Alcohol use
- Taking antacids and other heartburn medicines for a long period of time
- Abuse of laughing gas (nitrous oxide)
- Long term use of the medicine metformin
A lack of vitamin B12 may be due to dietary factors, including:
- Eating a strict vegetarian diet
- Poor diet in infants
- Poor nutrition during pregnancy
Symptoms
You may not have symptoms. Symptoms may be mild.
Symptoms may include:
- Diarrhea or constipation
- Fatigue, lack of energy, or lightheadedness when standing up or with exertion
Fatigue
Fatigue is a feeling of weariness, tiredness, or lack of energy.
Read Article Now Book Mark Article - Loss of appetite
Loss of appetite
A decreased appetite is when your desire to eat is reduced. The medical term for a loss of appetite is anorexia.
Read Article Now Book Mark Article - Pale skin
Pale skin
Paleness is an abnormal loss of color from normal skin or mucous membranes.
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- Shortness of breath, mostly during exercise
Shortness of breath
Breathing difficulty may involve:Difficult breathing Uncomfortable breathingFeeling like you are not getting enough air
Read Article Now Book Mark Article - Swollen, red tongue or bleeding gums
If you have low vitamin B12 level for a long time, it can cause nerve damage. Symptoms of nerve damage include:
- Numbness and tingling of hands and feet
- Loss of balance
- Problems concentrating
- Confusion or change in mental status (dementia) in severe cases
Dementia
Dementia is loss of brain function that occurs with certain diseases. Dementia may also be referred to as major neurocognitive disorder. Dementia du...
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Psychosis
Psychosis occurs when a person loses contact with reality. The person may: Have false beliefs about what is taking place, or who one is (delusions)S...
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Hallucinations
Hallucinations involve sensing things such as visions, sounds, or smells that seem real but are not. These things are created by the mind.
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Exams and Tests
The health care provider will perform a physical exam. This may reveal problems with your reflexes or sensations.
Tests that may be done include:
- Complete blood count (CBC)
Complete blood count
A complete blood count (CBC) test measures the following:The number of white blood cells (WBC count)The number of red blood cells (RBC count)The numb...
Read Article Now Book Mark Article - Reticulocyte count
Reticulocyte count
Reticulocytes are slightly immature red blood cells. A reticulocyte count is a blood test that measures the amount of these cells in the blood....
Read Article Now Book Mark Article - Lactate dehydrogenase (LDH) level
Lactate dehydrogenase
Lactate dehydrogenase (LDH) is a protein that helps produce energy in the body. An LDH test measures the amount of LDH in the blood.
Read Article Now Book Mark Article - Serum bilirubin level
- Serum vitamin B12 level
Serum vitamin B12 level
The vitamin B12 level is a blood test that measures how much vitamin B12 is in your blood.
Read Article Now Book Mark Article - Serum methylmalonic acid (MMA) level
Serum methylmalonic acid
The methylmalonic acid blood test measures the amount of methylmalonic acid in the blood.
Read Article Now Book Mark Article - Serum homocysteine level (amino acid found in blood)
- Anti-intrinsic factor antibody
- Anti-parietal cell antibody
Anti-parietal cell antibody
An antiparietal cell antibody test is a blood test that looks for antibodies against the parietal cells of the stomach. The parietal cells make and ...
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Other procedures that may be done include:
- Esophagogastroduodenoscopy (EGD) to examine the stomach and small intestine
Esophagogastroduodenoscopy
Esophagogastroduodenoscopy (EGD) is a test to examine the lining of the esophagus, stomach, and first part of the small intestine (the duodenum)....
Read Article Now Book Mark Article - Bone marrow biopsy if the diagnosis is not clear
Bone marrow biopsy
A bone marrow biopsy is the removal of marrow from inside bone. Bone marrow is the soft tissue inside bones that helps form blood cells. It is foun...
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Treatment
Treatment depends on the cause of B12 deficiency anemia. The goal of treatment is to increase your vitamin B12 level.
For people who have a low level of B12 due to a restricted vegetarian diet, taking B12 pills may resolve the issue.
For people with a health condition that causes B12 deficiency, treatment may include a shot of vitamin B12, often once a month. If you have a very low level of B12, you may need more shots in the beginning. It is possible you may need shots regularly for the rest of your life.
Your provider will also recommend that you eat a variety of foods.
Outlook (Prognosis)
People with this type of anemia often do well with treatment.
Long-term vitamin B12 deficiency can cause nerve damage. This may be permanent if you do not start treatment promptly after your symptoms begin. If nerve damage is severe or long-lasting, some damage may be permanent.
Vitamin B12 deficiency anemia most often responds well to treatment. It will likely get better when the underlying cause of the deficiency is treated.
Possible Complications
A woman with a low B12 level may have a false positive Pap smear. This is because vitamin B12 deficiency affects the way certain cells (epithelial cells) in the cervix look.
When to Contact a Medical Professional
Contact your provider if you have any of the symptoms of anemia.
Prevention
Eating a well-balanced diet can help ensure you get enough vitamin B12 from the foods you eat. However, it can't prevent anemia in people with certain health conditions that prevent their body from using vitamin B12 properly.
Shots of vitamin B12 can prevent anemia if you've had a surgery known to cause vitamin B12 deficiency.
Early diagnosis and prompt treatment can reduce or prevent complications related to a low vitamin B12 level.
There is no evidence that taking B12 supplements will prevent or treat dementia, Alzheimer disease, or other health conditions such as heart disease.
Reviewed By
Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Editorial update 08/19/2024.
Antony AC. Megaloblastic anemias. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 40.
Means Jr. RT. Approach to the anemias. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 144.
National Institutes of Health website. Vitamin B12: fact sheet for health professionals. ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/. Updated March 26, 2024. Accessed August 17, 2024.
Stabler SP. Megaloblastic anemias. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 150.