Vitamin B-12 Level Test: Purpose, Procedure & Results - Healthline

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Nutrition

What Is a Vitamin B-12 Test?

Medically reviewed by Adam Bernstein, MD, ScD — Written by Mara Tyler — Updated on March 19, 2024

When to test
Who gets tested
Side effects
Types of tests
Results
Treatment
Prevention

Vitamin B-12 is an important vitamin for many bodily functions, such as brain health, blood cell production, and proper nerve functioning. There are several ways to test your B-12 levels.

You can get your blood drawn or take a home urine test. These tests will look at the levels of your overall vitamin B-12 and methylmalonic acid (MMA).

Low B-12 levels can lead to symptoms including:

anemia
fatigue
heart palpitations
neurological problems
temporary infertility

People who eat a lot of red meat also tend to have higher-than-normal levels. High levels of vitamin B-12 can be a sign of liver disease or certain types of leukemia.

Vitamin B-12 deficiency is a common condition. Approximately 6% of adults under 60 in the United States and Unted Kingdom have low levels of vitamin B-12, according to the National Institutes of Health. In adults over 60, the rate rises to nearly 20%.

Many people, especially older adults and people with intestinal disorders, have trouble absorbing vitamin B-12 from food and oral supplements.

Learn whether vitamin B-12 can boost your energy levels.

When does your doctor order a vitamin B-12 test?

Your doctor might recommend a B-12 test if you have:

tingling in the hands and feet
problems with balance
a racing heart
confusion
dementia
weakness
loss of appetite

You may also take this test if your doctor suspects you might have pernicious anemia. Pernicious anemia is a reduction in red blood cells. It occurs when your intestines can’t absorb vitamin B-12, which is necessary for red blood cell production.

Pernicious anemia symptoms are not often seen in people younger than 30 years old. The average age of diagnosis is 60.

Symptoms of this condition include:

diarrhea or constipation
exhaustion
loss of appetite
pale skin
inflamed red tongue, or gums that bleed

High serum folate levels

Your doctor might also test your vitamin B-12 levels if you have high serum folate levels. High serum folate levels may mask vitamin B-12 deficiency and worsen the symptoms, according to the National Institutes of Health (NIH).

Serum folate measures the level of folic acid in the blood. Folic acid is necessary for your body’s growth and development and the production of red and white blood cells and platelets.

Read more about the symptoms of vitamin B-12 deficiency »

Who needs to take a vitamin B-12 test?

Your body doesn’t naturally produce vitamin B-12. It comes from animal products like fish, meat, and dairy. People who are at risk for vitamin B-12 deficiency are:

older adults
children
vegans
strict vegetarians
people with diabetes
people who’ve had gastric bypass surgery

New mothers who are breastfeeding may want to test their vitamin B-12 levels if they have symptoms or are in the at-risk group above. If a breast-feeding mother has low levels of B-12, her infant is at increased risk for neurological damage and developmental problems, according to Harvard Health Publications.

Some conditions may also affect your body’s ability to absorb B-12. Talk to your doctor if you have:

pernicious anemia
celiac disease, where your body’s immune system reacts to gluten by damaging the lining of the intestine
Crohn’s disease, an autoimmune condition that causes persistent inflammation of the gastrointestinal tract
atrophic gastritis, a condition where your stomach lining narrows and limits stomach acid production

Medications that may also affect the body’s vitamin B-12 levels include:

chloramphenicol, or Chloromycetin
proton pump inhibitors, such as Prilosec and Prevacid
H2 receptor blockers, such as Tagamet, Pepcid, and Zantac 360
metformin, for diabetes

Side effects and risks of a B-12 test

You might feel a pricking when your healthcare provider inserts the needle into your arm. But a blood draw is low risk and generally painless.

It’s also possible to feel a little sore or observe bruising on your arm for a few days after. Alert your healthcare provider if the pain is throbbing or if your arm swells after the test.

Talk to your doctor before the test if you have a bleeding disorder, such as hemophilia, or if you’ve had problems with blood clotting in the past. It’s possible to experience excessive bleeding where the needle punctures your skin.

It’s also important to tell your doctor about any medications or over-the-counter drugs you’re taking, as certain drugs may interfere with the test results.

Types of B-12 tests and how they’re performed

Preparing for a blood test

Your healthcare provider will tell you not to eat or drink for about six to eight hours before your test. You’ll want to make sure you’re well hydrated on the days before the test.

During the test, your healthcare provider will clean a small area of your arm or elbow with an antiseptic wipe or alcohol pad.

They might wrap an elastic band around the top of your arm to increase the flow of blood. Your healthcare provider will then insert the needle into your vein and collect your blood.

Once enough blood is drawn, your healthcare provider will remove the needle and apply a bandage. Your blood sample is then taken to a lab to measure for vitamin B-12 or other markers, like holoTC.

Preparing for the home tests

It’s possible to test your B-12 levels at home. Home test kits cost about $65.00 to $90.00 each and can be purchased online. Most home kits test your urine for the presence of MMA, which is linked to early stages of a vitamin B-12 deficiency.

You may need to send your urine sample to a laboratory. These kits will include a jar and mailing instructions. Others will include test strips that you dip into your urine sample yourself, allowing you to read your results right away.

Interpreting B-12 test results

Both high and low levels of vitamin B-12 may indicate an underlying problem. Low levels of B-12 can suggest:

malabsorption
celiac disease
Crohn’s disease
hyperthyroidism
lack of B12 in diet

High levels of B-12 can also be a sign of:

liver disease
certain types of leukemia
kidney failure

It’s also possible to have low or high levels of vitamin B-12 without other health concerns. Most health conditions will have additional symptoms other than abnormal vitamin B-12 levels.

Normal ranges can also vary from laboratory to laboratory, so it’s important to discuss your results with your doctor.

Vitamin B-12 results

Results based on picograms per milliliter (pg/mL)
below 150 pg/mL	low
160 to 950 pg/mL	normal
950 pg/mL	high

How to manage your B-12 levels

For people with high levels of B-12, treatment may involve adjusting your diet. This may mean eating less animal products like meats, dairy, and seafood.

If you’re diagnosed with a B-12 deficiency, the goal of treatment is to increase your level of vitamin B-12. Your treatment may include:

vitamin B-12 injection, with more frequent injections for those with severe deficiencies
daily vitamin B-12 supplements, such as Cyanocobalamin, which is a manmade vitamin B-12
regular administration of liquid B-12 through the nose
adhering to a diet rich in vitamin B-12

If your B-12 deficiency is the result of an underlying medical condition, your doctor will discuss treatment options.

What to eat to prevent vitamin B-12 deficiency

Some cases of B-12 deficiency are rooted in underlying health problems, but it’s also possible to take preventative measures. Preventative measures include paying close attention to your diet, especially if you’re vegetarian or vegan.

One serving of fortified breakfast cereal may fulfill 25 to 100 percent of your daily intake value, depending on the brand. Three ounces of cooked salmon may offer over 100 percent of your daily intake value.

You may also find B-12 in:

seafood
liver, pork, and beef
chicken and poultry
fortified soymilk
dairy, such as milk, yogurt, cheese
vitamin supplements

You may also find some soy products, including miso, with B-12, but these don’t contain significant amounts of B-12.

How much vitamin B-12 do you need?

How much B-12 you need depends on your age and if you are pregnant or breastfeeding. The table below shows how much

Age	Daily amount based on microgram (mcg)
birth to 6 months old	0.4 mcg
7 to 12 months old	0.5 mcg
1 to 3 years old	0.9 mcg
4 to 8 years old	1.2 mcg
9 to 13 years old	1.8 mcg
14 to 18 years old	2.4 mcg
adults, 19 and older	2.4 mcg
pregnant women	2.6 mcg
breastfeeding women	2.8 mcg

While high vitamin B-12 may be a sign of other conditions, consuming excess vitamin B-12 doesn’t appear to cause any adverse health effects.

How we reviewed this article:

SourcesHistoryHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

Andrés E, et al. (2013). The pathophysiology of elevated vitamin B-12 in clinical practice.https://academic.oup.com/qjmed/article/106/6/505/1538806
Langan RC & Goodbred AJ. (2017). Vitamin B12 deficiency: Recognition and management.https://www.aafp.org/pubs/afp/issues/2017/0915/p384.html
Mangels, R. (2012). Vitamin B12 in the vegan diet.https://www.vrg.org/nutrition/b12.php
Nexo E & Hoffmann-Lücke E. (2011). Holotranscobalamin, a marker of vitamin B-12 status: analyticalaspects and clinical utility.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3127504/
Scutti S. (2013). High levels of vitamin B-12 may be linked to increased cancer risk.https://www.medicaldaily.com/high-levels-vitamin-b12-may-be-linked-increased-cancer-risk-263123
Seeniann J. & Hoegerl C. (2009). Nutritional deficiencies after gastric bypass surgery.https://www.degruyter.com/document/doi/10.7556/jaoa.2009.109.11.601/html
Vitamin B12: Dietary supplement fact sheet for health professionals. (2022).https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/
Vitamin B12 level. (n.d.).https://www.mountsinai.org/health-library/tests/vitamin-b12-level
Vitamin B12 level. (2022).https://www.ucsfhealth.org/medical-tests/vitamin-b12-level

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Medically reviewed by Adam Bernstein, MD, ScD — Written by Mara Tyler — Updated on March 19, 2024

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