Vitamin B12 deficiency can occur when the body needs more vitamin B12 than it receives from the diet. Alternatively, the condition may occur when the body is unable to use the vitamin B12 from the diet. A shortage of vitamin B12 can lead to
. Anemia is the insufficient delivery of oxygen by red blood cells from the lungs to the cells of the body. The sooner this anemia is treated, the more favorable the outcome. If you suspect you have this condition, contact your doctor immediately.
Red Blood Cells
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There are many causes of vitamin B12 deficiency. Some are listed below. Removal of part of the small intestine or stomachAdvancing age
Long-term use of certain acid-reducing stomach medications:
H2 blockersProton pump inhibitors
(inflammation of the stomach) due to:
Iron deficiency anemia
Bacterial infection with
Helicobacter pyloriChronic alcohol abuseAutoimmunity
Disorders affecting vitamin absorption:
Crohn’s diseaseCystic fibrosisCeliac diseaseTropical sprueWhipple’s diseaseTuberculosis
(lack of intrinsic factor)
Inadequate intake of vitamin B12
Long-term veganism (nonconsumption of animal products) or vegetarianismBreastfed infants of vegan or vegetarian mothersPoor infant nutritionInadequate nutrition for a pregnant womanChronic alcohol abuse
Stillness of the intestinal contents which can be caused by:
Abnormal narrowness of intestinesPockets in intestinesConnections between loops of the intestineBlind intestinal loops
Intestinal blockage which can be caused by:
Inflammation of the intestine due to
Inability to use vitamin B12:
Lack of a needed enzymeCancerMalnutritionNonfunctioning transport protein
Increased need of vitamin B12:
Other types of anemia
Over-use of nitrous oxide:
Frequent useExtended single use of nitrous oxide (more than six hours)
A risk factor is something that increases your chance of getting a disease or condition. The following factors increase your chance of developing vitamin B12 deficiency. If you have any of these risk factors, tell your doctor: Alcoholism
Use of certain drugs:
Biguanides for diabetesPara-aminosalicylic acid for tuberculosisCalcium-chelating drugs taken by mouthColchicineNeomycinCimetidineCholestyramineAge: over 50 years oldStrict vegan or vegetarian diet
The symptoms of pernicious anemia can vary from person-to-person. Symptoms may change or worsen over time. If you experience any of these symptoms, do not assume it is due to this anemia. These symptoms may be caused by other health conditions. If you experience any one of them, see your physician.
Symptoms can include: Sensation of pins and needles in feet or hands
diarrheaStinging sensation on the tongue or smooth red tongueSubstantial weight lossInability to distinguish the colors yellow and blueTirednessPalenessLoss of hungerAltered sense of tasteConfusionDepressionImpaired sense of balance, especially in the darkRinging in the earsCracked lipsYellow skinFeverInability to sense vibrations in feet or legsDizziness when changing to standing positionRapid heart rate
Your doctor will ask about your symptoms and medical history, and perform a physical exam. Tests may include the following: Complete blood count (CBC)—a count of the number of red and white blood cells in a blood sampleVitamin B12 level—a test that measures the amount of vitamin B12 in the bloodMethylmalonic acid (MMA) level—a measurement of the amount of methylmalonic acid in the blood; this test determines whether a vitamin B12 deficiency exists.Homocysteine level—a test that measures the amount of homocysteine in the blood (homocysteine is a building block of protein). The homocysteine level will be elevated if there is a shortage of vitamin B12, folate, or vitamin B-6.Schilling test—a test in which a harmless amount of radiation is used to assess whether a vitamin B12 deficiency exists
(rarely used)Red blood cell folate level—a measurement of the amount of a B vitamin called folateGastrin level—a test that may help determine the cause of a vitamin B12 deficiencyIntrinsic factor assay—a measurement of the amount of a protein called intrinsic factor normally produced in the stomach; this test helps to rule out pernicious anemia as the cause of symptoms.Bone marrow staining—a test that shows whether an iron deficiency exists
Talk with your doctor about the best treatment plan for you.
options include the following:
This treatment consists of high doses of an oral vitamin B12 supplement.
The doctor may advise the patient to receive injections of vitamin B12 into a muscle. Injections of vitamin B12 may be given 2-4 days per week. When blood tests show improvement, the doctor may give injections on a monthly basis.
This type of medication may be needed in cases where bacterial overgrowth in the intestines exists. The bacteria compete with the body to absorb the vitamin B12 in the intestines.
The doctor gives the patient a supplement of vitamin B12 that is placed in the nose.
The physician will recommend this treatment when an iron deficiency exists. In this case, the doctor will tell the patient to take iron supplements before treating with vitamin B12.
To help reduce your chances of developing a deficiency of vitamin B12, take the following steps: Avoid long-term over-consumption of alcohol.
As directed by your doctor, take a daily supplement containing vitamin B12.
As directed by your doctor, give vitamin B12 to your breastfed baby if you are a vegan or vegetarian.Avoid overuse of nitrous oxide.Seek diagnosis and treatment of any suspected tapeworm infestation.Have your doctor check you for iron deficiency.
Undergo testing if your doctor suspects you are infected with the bacterium
Have your doctor monitor your health closely if you are taking the following drugs:
BiguanidesAminosalicylic acidCalcium-chelating drugs taken by mouthColchicineNeomycinCimetidineCholestyramine
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Last reviewed October 2012 by Daus Mahnke, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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