Vitamin B12 Blood Test

Vitamin B12 is an essential water-soluble vitamin that plays a critical role in many bodily functions, including DNA synthesis, the formation of red blood cells, and the proper functioning of the nervous system. It can be found in animal-derived foods such as meat, fish, poultry, eggs, and dairy products, as well as in fortified foods and supplements. Vitamin B12 deficiency can lead to anemia, nerve damage, and cognitive impairment.

Vitamin B12 is a water-soluble vitamin. Water-soluble vitamins dissolve in water. After the body uses these vitamins, leftover amounts leave the body through the urine.

The body can store vitamin B12 for years in the liver.

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Vitamin B12

A Vitamin B12 blood test measures the amount of Vitamin B12 in your bloodstream. This test is used to determine if a person has a Vitamin B12 deficiency.

Vitamin B12, like the other B vitamins, is important for protein metabolism. Vitamin B12 is essential for the production of red blood cells, DNA synthesis, nerve function, and the metabolism of fats and proteins. It also helps maintain the health of nerve cells and supports brain function.

Low levels of B12 can cause:

• Anemia
• Loss of balance
• Numbness or tingling in the arms and legs
• Weakness

Vitamin B12 requires a protein called intrinsic factor, produced in the stomach, for proper absorption in the small intestine. Certain conditions, such as pernicious anemia or gastrointestinal disorders, can affect the absorption of vitamin B12.

Causes of vitamin B12 deficiency include:

• Are over the age of 50.
• Not enough vitamin B12 in diet (rare, except with a strict vegetarian diet).
• Have had stomach or intestinal surgery, such as weight loss surgery.
• Diseases that cause malabsorption (for example, celiac disease and Crohn disease).
• Lack of intrinsic factor, a protein that helps the intestine absorb vitamin B12.
• Above normal heat production (for example, with hyperthyroidism).
• Pregnancy

An increased vitamin B12 level is uncommon. Usually, excess vitamin B12 is removed in the urine.

Conditions that can increase B12 level include:

• Liver disease (such as cirrhosis or hepatitis).
• Myeloproliferative disorders (for example, polycythemia vera and chronic myelogenous leukemia).

Vitamin B12 is naturally found in animal-based foods, including meat, fish, poultry, eggs, and dairy products. Some fortified plant-based foods, such as fortified cereals and nutritional yeast, can also provide vitamin B12.

Vegetarians and vegans who do not consume animal-based products are at a higher risk of vitamin B12 deficiency. Older adults, individuals with gastrointestinal disorders, and those who have undergone certain gastrointestinal surgeries may also be at an increased risk.

A blood sample is needed.

You should not eat or drink for about 6 to 8 hours before the test.

Certain medicines may affect the results of this test. Your health care provider will tell you if you need to stop taking any medicines. Do not stop any medicine before talking to your provider.

Medicines that can affect the test result include:

• Colchicine
• Neomycin
• Para-aminosalicylic acid
• Phenytoin

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Your provider may also recommend a vitamin B12 test if you have certain nervous system symptoms. A low level of B12 can cause numbness or tingling in the arms and legs, weakness, and loss of balance.

Other conditions for which the test may be done include:

• Sudden severe confusion (delirium)
• Loss of brain function (dementia)
• Dementia due to metabolic causes
• Nerve abnormalities, such as peripheral neuropathy

Normal Results
Normal values are 160 to 950 picograms per milliliter (pg/mL), or 118 to 701 picomoles per liter (pmol/L).

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different samples. Talk to your provider about what your specific test results mean.

What Abnormal Results Mean
Values of less than 160 pg/mL (118 pmol/L) are a possible sign of a vitamin B12 deficiency. People with this deficiency are likely to have or develop symptoms.

Older adults with a vitamin B12 level less than 100 pg/mL (74 pmol/L) may also have symptoms. Deficiency should be confirmed by checking the level of a substance in the blood called methylmalonic acid. A high level indicates a true B12 deficiency.

Recommendations for vitamin B12, as well as other nutrients, are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board at the National Academies of Sciences, Engineering, and Medicine. DRI is a term for a set of reference intakes that are used to plan and assess the nutrient intakes of healthy people. These values, which vary by age and sex, include:

Recommended Dietary Allowance (RDA): The average daily level of intake that is enough to meet the nutrient needs of nearly all (97% to 98%) healthy people. An RDA is an intake level based on scientific research evidence.

Adequate Intake (AI): This level is established when there is not enough scientific research evidence to develop an RDA. It is set at a level that is thought to ensure enough nutrition.

Dietary reference intakes for vitamin B12:

Infants (AI)

• 0 to 6 months: 0.4 micrograms per day (mcg/day)
• 7 to 12 months: 0.5 mcg/day

Children (RDA)

• 1 to 3 years: 0.9 mcg/day
• 4 to 8 years: 1.2 mcg/day
• 9 to 13 years: 1.8 mcg/day

Adolescents and Adults (RDA)

• Males and females age 14 and older: 2.4 mcg/day
• Pregnant teens and women: 2.6 mcg/day
• Breastfeeding teens and women: 2.8 mcg/day

The best way to meet your body’s vitamin B12 needs is to eat a wide variety of animal products.

Supplemental vitamin B12 can be found in the following:

• Almost all multivitamins. Vitamin B12 is better absorbed by the body when it is taken along with other B vitamins, such as niacin, riboflavin, and vitamin B6, along with magnesium.
• A prescription form of vitamin B12 can be given by injection or as a nasal gel.
• Vitamin B12 is also available in a form that dissolves under the tongue (sublingual).

SST tube of blood, serum

24 hours

Price: $79