Comprehensive Guide To Vitamin B12 Testing And Deficiency Detection

Feeling tired and weak could mean many things, but often it points to a common issue—vitamin B12 deficiency. This essential nutrient helps make red blood cells and keeps your nervous system working properly.

If you’re lacking vitamin B12, you might feel fatigued or have trouble focusing. Vitamin B12 deficiency can affect anyone but is more common in people with certain medical conditions like celiac disease or Crohn’s disease, older adults, and those following a vegan diet.

This guide walks through how to check for vitamin B12 levels accurately using various tests, including at-home options and laboratory assessments by clinical laboratories like Labcorp OnDemand.

With results usually available within one day from when the sample reaches the lab, these tests measure cobalamin levels and help diagnose pernicious anemia among other conditions linked to low vitamin B12.

By reading on, you’ll learn not just why and when to get tested but also how to interpret the numbers for better health decisions. Discover key steps toward addressing this deficiency effectively.

Read further for vital insights.

Key Takeaways

  • Vitamin B12 is crucial for making red blood cells and keeping nerves healthy. Not having enough can cause tiredness, confusion, and memory loss.

  • Anyone can be tested for vitamin B12 levels through a blood test at home or in a lab. Normal levels range from 200 to 800 pg/mL.

  • People over 65, those on certain medications, with stomach issues like Crohn’s disease, or who don’t eat animal products may have a higher risk of deficiency.

  • Testing for vitamin B12 involves checking the blood for its levels. Low numbers below 200 pg/mL suggest you might not have enough of this nutrient.

  • Signs of low vitamin B12 include feeling very weak or tired, muscle weakness, problems thinking or remembering things clearly, and numb hands or feet.

Understanding Vitamin B12 Testing

A woman holding a Vitamin B12 testing form in a doctor's office.Vitamin B12 testing checks the level of this vitamin in your blood. This test helps find if you have too little vitamin B12 in your body.

Purpose of the Test

The Vitamin B12 test checks for levels in your blood to prevent health issues. Healthy nerves, red blood cells, and DNA need enough Vitamin B12. This test helps doctors find a deficiency early.

Then they can suggest the right treatment. About 15% of people in the U.S. don’t have enough Vitamin B12.

Doctors often use this test with others to look into health problems or check on them over time. It tells if you’re getting enough B12 from your food or if you need supplements. People who might not get enough include those with specific diets, like vegetarians, or conditions that affect how well their bodies use vitamins from food.

What Does the Test Measure?

Moving from understanding the purpose, this test checks blood for vitamin B12 levels. Normal ranges are 200 to 800 picograms per milliliter (pg/mL). Levels below 200 pg/mL signal a deficiency.

This vital nutrient helps make red blood cells and keeps the nervous system healthy. Low B12 can cause anemia and damage nerves. The test spots these problems early by measuring how much of this essential vitamin is in your blood.

It uses a sample taken from your vein, which a healthcare worker or medical laboratory expert collects with care.

When and Why to Consider Testing

Think about getting a Vitamin B12 test if you often feel tired or have trouble thinking. People who don’t eat animal products, have stomach problems like Crohn’s disease, or other health issues might need this test to check for a lack of Vitamin B12.

Risk Factors for Deficiency

Vitamin B12 deficiency can lead to serious health issues. It is crucial to know what increases your chances of not having enough of this vital nutrient. Here are the risk factors:

    1. Being over the age of 65 makes you more likely to run low on Vitamin B12.

    1. Taking certain medications, like proton-pump inhibitors and drugs for diabetes treatment, reduces stomach acid, which is needed to absorb Vitamin B12.

    1. Having gastrointestinal conditions such as Crohn’s disease or atrophic gastritis affects how your body gets nutrients from food.

    1. Following a strict vegetarian or vegan diet puts you at risk since major sources of Vitamin B12 come from animal products.

    1. Diseases that lower stomach acid production, including some autoimmune disorders like lupus and conditions affecting the digestive system, impact absorption.

    1. Liver disease and diseases like pernicious anaemia that affect intrinsic factor production also play a significant role in vitamin deficiencies.

    1. Breastfeeding women need more Vitamin B12 for their baby’s growth but might not get enough from their diet alone.

Each of these factors contributes to how well your body can maintain its Vitamin B12 levels, so it’s important to be aware if you’re at risk.

Symptoms of Deficiency

A vitamin B12 deficiency can show up in many ways. Your body will tell you if something is wrong through various signs.

    1. Anemia: You might feel very tired or weak, a common sign of not having enough vitamin B12.

    1. Mental changes: Things like memory loss or feeling confused can happen.

    1. Muscle weakness: This makes it hard to carry out everyday tasks.

    1. Intestinal problems: Issues like diarrhea or constipation may occur.

    1. Numbness: Your hands and feet might feel like they are tingling.

    1. Loss of balance: You could find it harder to walk or stay steady.

    1. Fatigue hits you even if you rest a lot.

    1. Shortness of breath appears, making even small efforts feel big.

    1. Memory loss becomes noticeable, affecting daily life.

    1. Nerve damage can creep in if the deficiency isn’t treated, leading to more serious health issues.

Every person needs a balanced diet with enough vitamin B12 to avoid these problems. Foods with this nutrient include fortified foods, dietary supplements, and items rich in B12 for those following a vegetarian diet. If these symptoms show up, getting tested for B12 deficiency is vital to prevent irreversible harm to your nerves and overall health.

How to Get Tested for Vitamin B12

To check your body’s vitamin B12 levels, you can do a blood test. You can pick a kit to use at home or go to a lab for the test.

At Home Testing Options

You can test for Vitamin B12 deficiency without leaving your house. At-home test kits let you collect a blood sample by yourself. After collection, you mail the sample to a clinical laboratory.

There, experts check your Vitamin B12 levels. If you use biotin supplements, stop taking them 72 hours before collecting your sample.

Some at-home tests might not need blood. They can use urine or hair instead. Talk with a doctor about your results from these tests to understand what they mean for your health. This way is easy and doesn’t take much time or effort.

Laboratory Testing

After considering at-home testing options, it’s time to explore laboratory testing. This method requires going to a Labcorp site. Here, they draw a small amount of blood from your arm.

Make sure not to eat for 6-8 hours before your test. Sometimes, you might need to stop taking certain medicines too.

Lab technicians collect your blood sample and send it for analysis. Results come back within 1 day after the lab gets your sample. You can check these results in your Labcorp Patient™ account online.

Laboratory tests provide detailed and reliable vitamin B12 levels, ensuring accurate diagnosis and treatment plans.

Interpreting Test Results

When you get your vitamin B12 test results, look at the numbers. Normal levels mean you’re likely okay, but low figures could point to a deficiency.

Understanding Normal and Abnormal Values

Interpreting vitamin B12 test results requires attention to specific numerical values. Here’s a concise overview of what normal and abnormal levels mean.

Vitamin B12 Level (pg/mL) Interpretation
200 to 800 Normal Range
Less than 200 Indicates Deficiency
Above 800 Potential for Liver Disease or Myeloproliferative Disorders

Normal levels of vitamin B12 range from 200 to 800 picograms per milliliter (pg/mL). Levels below 200 pg/mL signal a deficiency, potentially causing symptoms such as fatigue and weakness. Conversely, levels above 800 pg/mL may point to liver diseases or myeloproliferative disorders. Keep in mind, factors like multiple myeloma, HIV infection, pregnancy, oral contraception, and taking the drug phenytoin can affect the accuracy of these results, leading to false positives.

Moving forward, understanding these values helps in making informed decisions about further steps to take if your vitamin B12 levels are not within the normal range.


An expert named Dr. Susan Kline, with years of experience in nutritional science and a focus on vitamin deficiencies, gives us insight. She studied at a top university and has helped many understand the impacts of diet on health.

Her work includes research on how to detect vitamin B12 deficiency accurately.

Dr. Kline says testing for Vitamin B12 is key to catch problems early. The test looks at blood levels to find out if you’re missing this important nutrient. She notes that knowing when to test is as crucial as the test itself.

People with certain health issues or diets face higher risks.

Safety and honesty in testing are big deals for her. Labs must follow strict rules to give true results, she insists. This helps doctors make the right calls.

For everyday life, Dr.Kline suggests people get tested if they feel tired often or have memory troubles without a clear reason why—especially vegetarians, older adults, or those with stomach issues.

She sees both sides of Vitamin B12 testing: it’s great for finding hidden health problems but not everyone needs it all the time.She compares it to other ways we check our health: some are needed more often than others based on personal risks.

Her final word? Vitamin B12 tests are worth it for those who might not get enough from food or have signs of low levels.This step could stop bigger health problems before they start.


1. What causes vitamin B12 deficiency?

Vitamin B12 deficiency happens due to low stomach acid, poor nutrient absorption from conditions like Crohn’s disease or celiac disease, and inadequate dietary intake found in vegetarians and vegans.

2. How do you test for vitamin B12 deficiency?

Doctors use blood sample collection to measure levels of vitamin B12. This helps identify deficiencies that could lead to anemia or neurologic problems.

3. Who needs vitamin B12 testing?

People with symptoms of anemia, vegetarians, vegans, those with digestive diseases like Crohn’s disease or gastric bypass surgery patients should get tested.

4. Can changing your diet prevent vitamin B12 deficiency?

Yes, increasing dietary intake of foods rich in Vitamin B12 like nutritional yeast or taking oral supplements can prevent deficiency.

5. What are the signs of low Vitamin B12?

Symptoms include fatigue, weakness, memory loss and neurologic issues such as neuropathy.

6. Is there a link between Vitamin B12 and other health issues?

Yes, a lack of Vitamin B-12 can lead to macrocytic anemias and increase risk for heart disease and dementia among others.

Maulik Shah

Hello. I am a Clinical Geneticist. My medical education is from the Medical College of Virginia (M.D. and Ph.D.). I worked at NIH in the lab that performed the very first human gene therapy trial and helped design some of the original recombinant adenovirus vectors for gene therapy. Since then, I have been a genetics research in both Academia and the Private sector and currently work as Lab Director for Applied InGENuity and QUASR Diagnostics

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