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Vitamin B12 Test

This measures the level of vitamin B12 in your blood.

Collection method

Typically blood (venipuncture)

Test preparation



Ages 18+ only; Could vary by provider

Turnaround time

Typically 48-72 hours

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What is vitamin B12?

Vitamin B12 is a vitamin that comes from animal food sources. These sources include dairy, eggs, poultry, fish, and red meat. When you eat a food containing vitamin B12, your body absorbs the vitamin in your intestines using a specific protein called intrinsic factor (IF) created by cells in your stomach.

Vitamin B12 is used for many essential functions in the body, including making DNA, making red blood cells, and creating the specialized lining of your nerve cells known as the myelin sheath according to the National Library of Medicine (NLM). This makes vitamin B12 an essential vitamin for the proper functioning of your nervous system and the system involved in making new blood cells (hematologic system).

According to the NLM, any excess vitamin B12 that you get through your diet gets stored in your liver. If you go without eating foods with vitamin B12, your body can rely on the vitamin B12 in your liver for a while.

Because vitamin B12 is so vital for the basic function of your nervous and hematologic systems you can develop symptoms of a vitamin B12 deficiency when you don’t have a high enough level of vitamin B12 in your blood, according to the NLM.

These symptoms may include feeling very tired or weak, feeling numbness or tingling in your extremities, or feeling like you are off-balance, among others, according to the NLM.

Who should get a vitamin B12 test?

If you are interested in a health screening that checks your blood glucose level and cholesterol level, a vitamin B12 test is another helpful tool to assess your overall health. Knowing your vitamin B12 levels is helpful information that can help you make lifestyle changes, reports the NLM.

Beyond general screenings, certain people should get a vitamin B12 test. These groups are based on the three most common causes of vitamin B12 deficiency:

  • A problem with absorbing B12 in the gut
  • Not getting enough vitamin B12 in the diet
  • An autoimmune condition that attacks the intrinsic factor (IF) protein that is essential for helping your body break down and use vitamin B12.

According to health experts at the Harvard University School of Public Health, up to 15% of people have a vitamin B12 deficiency. The following groups of people are at a higher risk of experiencing this condition:

  • People who avoid eating animal food sources: One of the most common causes of a vitamin B12 deficiency is a vegan diet or any other eating pattern that directly avoids animal food sources such as eggs, red meat, poultry, fish, or dairy.
  • People who have an autoimmune condition known as pernicious anemia: In this condition, the cells of the stomach that create intrinsic factors become damaged. This means that even if you are eating enough vitamin B12, your body doesn’t have the tools it needs to absorb the vitamin and use it for its processes.
  • People who have acid reflux disease: People who struggle with gastroesophageal reflux disorder (GERD) may take medications to reduce their stomach acid. This can interfere with how vitamin B12 gets released from food in the stomach.
  • The elderly: Elderly people have decreased stomach acid, which can interfere with how vitamin B12 gets released from food in the stomach.
  • People who have had gastrointestinal surgeries: A stomach or intestinal surgery that removes a significant amount of tissue can remove the cells that help your body produce intrinsic factor (IF) or absorb vitamin B12.
  • People who have specific gastrointestinal conditions: Illnesses like celiac disease or Crohn’s disease can decrease the absorption of Vitamin B12 in the gut.
  • People who abuse alcohol: Chronic alcoholism can reduce your body’s absorption of Vitamin B12, and people who drink heavily may be less likely to meet their dietary needs daily, as well.

How is vitamin B12 tested?

Vitamin B12 testing is done through a blood test. A healthcare professional will take a blood sample using a venipuncture technique, and send it to a laboratory for analysis. Home tests use a blood sample collected through a finger stick.

How to get a vitamin B12 test

There are two ways you can get a Vitamin B12 test: you can self-order either an in-person or at-home vitamin B12 test through companies like Solv, Quest, LabCorp, etc, or you can visit with a healthcare provider to receive a referral for one.

Depending on your specific medical situation, as well as any symptoms you may be having, your healthcare provider may recommend a vitamin B12 test. This test may be particularly helpful if you have risk factors for a vitamin B12 deficiency or if you are having unexplained symptoms of fatigue, weakness, numbness, or tingling.

When your healthcare provider orders a vitamin B12 test, you may have the test performed at the clinic or an outside lab. You may also be able to order an at-home vitamin B-12 test online without a healthcare provider’s order. However, this can make it difficult to interpret and act on results on your own, especially if your test results are abnormal.

What are the different types of vitamin B12 tests?

There are different types of vitamin B12 tests, including serum vitamin B12, active vitamin B12, and methylmalonic acid (MMA) testing.

According to the NLM, serum vitamin B12 is the most common test used to measure vitamin B12 levels in the blood. This test measures the amount of vitamin B12 that is bound to a protein called transcobalamin in the blood.

Active vitamin B12 testing measures the amount of biologically active vitamin B12 in the blood. This test is often used to detect early vitamin B12 deficiency.

Methylmalonic acid (MMA) testing measures the amount of a substance called MMA in the blood. High levels of MMA in the blood may indicate a vitamin B12 deficiency, according to the NLM.

What to expect with a vitamin B12 test

Vitamin B12 is a simple blood test. Your healthcare provider will use a small needle to draw blood from a vein—usually in a vein in your arm because these are usually the most easily accessed. The blood draw should cause minimal pain.

Your Vitamin B12 test result may be available that same day, but the turn-around time depends on the laboratory.

How to prepare for a vitamin B12 test

According to the NLM, you should fast (not eat or drink anything except water) for 6 to 8 hours before having a Vitamin B12 test. It’s important to tell your healthcare provider who orders the test about any medications that you take daily. This is because, according to the National Library of Medicine, certain medications can affect your test results, including medications for gout or seizure disorders. Before getting your blood drawn, the CDC recommends the following steps:

  • Wear comfortable clothing, with sleeves that are easily pulled up to access your arms.
  • Hydrate yourself well by drinking water. This will make your veins easier to find during the procedure.
  • Bring a snack with you to eat right after your procedure.

What to expect during a vitamin B12 test

A venipuncture for collecting a blood sample is usually a quick and painless procedure. A healthcare provider or lab technician will locate the best spot for the venipuncture (usually on the arm or hand). Then they will clean the area with an antiseptic, and use a small needle to collect the blood sample.

After the test

After your test, you may have to apply pressure to the venipuncture site for a few minutes. Your healthcare provider or lab technician will give you instructions on when to remove the bandage.

Vitamin B12 Test Results

The results of your vitamin B12 test will appear as a single number within a specific range (the range varies depending on the kind of test used).

A healthcare provider can help you understand your vitamin B12 level and how it fits into the context of your general health.

How long does it take to get results from vitamin B12 testing?

The time it takes to get the results of a vitamin B12 test can vary depending on the type of test and the lab that conducts the analysis. In most cases, results from a standard serum vitamin B12 test are available within 24-48 hours according to LabCorp. While results from an active vitamin B12 test can take up to several days.

What to do if a vitamin B12 test is low

If you have a Vitamin B12 result that is lower than the normal range, your healthcare provider can help you determine your next steps. This may include lifestyle changes (such as deliberately trying to include more animal food sources in your diet) or beginning a Vitamin B12 supplement. If your level is extremely low and you are having severe symptoms, further testing may be needed, if recommended by your healthcare provider.

Finding a vitamin B12 test

Your healthcare provider may recommend the test if you have risk factors for low vitamin B12 or are experiencing symptoms. Alternatively, you can request the test yourself through Solv. Once you’ve ordered the test online, you will be sent to a Solv-affiliated lab for your testing procedure.

Can I get a vitamin B12 test at home?

Yes, you can get a vitamin B12 test at home using a variety of at-home testing kits. These kits typically involve collecting a small blood sample through a finger prick or saliva sample and sending it to a laboratory for analysis.

It's important to note that at-home testing kits may not be as accurate as testing done in a medical setting and that any abnormal results should be confirmed with a healthcare professional. Additionally, if you have any medical conditions or are taking medications, it is important to talk to your doctor before using an at-home testing kit.

Cost of a Vitamin B12 test

The cost of vitamin B12 testing will vary depending on your location, the type of test, and your insurance coverage. According to CostHelper Health, the national average for a vitamin B12 test is $25 to $200.

You can order a vitamin B12 test through Solv for between $49 and $79.

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Vitamin B12 Test FAQs

Find answers to the most commonly asked questions about lab tests.

Vitamin B12 tests are generally accurate but may produce false results in some cases according to the Mayo Clinic. For example, people with pernicious anemia may have low levels of vitamin B12 in their blood despite having normal or high levels of the vitamin in their tissues.
The normal range for vitamin B12 levels in the blood is 200-900 picograms per milliliter (pg/mL), according to the Mayo Clinic.
Vitamin B12 deficiency can be treated through a variety of methods, depending on the severity and underlying cause of the deficiency. Here are some common treatments for vitamin B12 deficiency, according to the CDC:Vitamin B12 injections: For severe vitamin B12 deficiency, injections of the vitamin may be necessary. These injections can be given daily or weekly until vitamin B12 levels return to normal.Oral supplements: For less severe cases of vitamin B12 deficiency, oral supplements of the vitamin may be effective. These supplements can be taken in pill form or as a sublingual tablet (a tablet that dissolves under the tongue).Dietary changes: In some cases, increasing the intake of vitamin B12-rich foods, such as meat, fish, dairy products, and eggs, may be enough to correct a vitamin B12 deficiency.Treatment of underlying conditions: If a medical condition is causing the vitamin B12 deficiency, treatment of the underlying condition may be necessary to restore vitamin B12 levels.
The two main types of vitamin B12 testing are serum vitamin B12 testing and active vitamin B12 testing according to the NIH.Serum vitamin B12 testingSerum vitamin B12 testing measures the total amount of vitamin B12 in the blood, including both active and inactive forms. This type of test is widely used and is often the first test ordered to screen for vitamin B12 deficiency.Active vitamin B12 testingActive vitamin B12 testing measures only the biologically active form of vitamin B12 in the blood, which is known as holotranscobalamin (holoTC). This type of test is more specific and may be more accurate in detecting vitamin B12 deficiency than serum vitamin B12 testing.
Yes, there are certain foods and supplements that can affect vitamin B12 test results. Here are some examples, as outlined by the NIH:Vitamin B12 supplements: Taking vitamin B12 supplements can cause high levels of the vitamin in the blood, which can affect test results.Antibiotics: Some antibiotics, such as tetracyclines and aminoglycosides, can interfere with vitamin B12 absorption and metabolism, which can affect test results.Antacids: Some antacids, such as proton pump inhibitors (PPIs) and H2 blockers, can interfere with vitamin B12 absorption and metabolism, which can affect test results.High-dose vitamin C: High doses of vitamin C can interfere with vitamin B12 absorption and metabolism, which can affect test results.Vegetarian or vegan diet: Vegetarian and vegan diets can be low in vitamin B12 due to the lack of animal meat sources. This can lead to low levels of the vitamin in the blood and affect test results.It's important to talk to your healthcare provider about any medications or supplements you are taking before getting a vitamin B12 test. Additionally, if you have any medical conditions or are taking medications, it is important to talk to your doctor before getting a vitamin B12 test.
Low levels of vitamin B12 can be caused by a variety of factors, including dietary deficiencies, medical conditions, and medications. Here are some common causes of low vitamin B12 levels, as noted by the NIH:Inadequate dietary intake: Vitamin B12 is found primarily in animal products, such as meat, fish, dairy, poultry, and eggs. People who follow a vegetarian or vegan diet may be at higher risk of vitamin B12 deficiency if they do not consume adequate amounts of fortified foods or supplements.Malabsorption disorders: Certain medical conditions, such as pernicious anemia, celiac disease, Crohn's disease, and atrophic gastritis, can interfere with vitamin B12 absorption in the digestive tract.Surgery: People who have had surgery to remove part of the stomach or small intestine may be at higher risk of vitamin B12 deficiency due to reduced absorption.Medications: Certain medications, such as metformin, proton pump inhibitors (PPIs), and H2 blockers, can interfere with vitamin B12 absorption and increase the risk of deficiency.
Vitamin B12 deficiency can cause a variety of symptoms, which can vary depending on the severity and duration of the deficiency. The common symptoms of vitamin B12 deficiency according to the NIH and CDC are:Fatigue and weaknessNumbness or tingling in the hands and feetDifficulty walking or balance problemsAnemia

This publication is not intended to solicit the purchase of laboratory testing from any individual consumer.

Dr. Rob Rohatsch, MD

Updated on Jan 25, 2023

Medically reviewed by

Dr. Rob Rohatsch, MD

Dr. Rob Rohatsch currently serves as Chief Medical Officer for Solv Health. Dr. Rohatsch brings his extensive background in multi-site ambulatory medicine operations, on-demand healthcare, and consumerism to Solv, where he helps drive strategic initiatives in a cross functional executive role. He brings comprehensive healthcare expertise ranging from medical group operations to revenue cycle management and clinical expertise.

Dr. Rohatsch completed his military service in the US Air Force and earned his MD from Jefferson Medical College of Thomas Jefferson University. Dr. Rohatsch served on the Yale School of Medicine faculty teaching at the medical school and is currently on faculty at the Haslam School of Business at the University of Tennessee teaching in the Executive MBA Program. He also serves on several boards and chairs The TJ Lobraico Foundation.

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