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Vitamin B12 Blood Test

Updated on: April 1, 2021
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Vitamin B12 deficiency is one of the most common conditions within the general human population. One study showed that as many as 46 percent of adults aged 30 to 70 are deficient in vitamin B12. This is a scary number when you think about all of the positive benefits this vitamin provides.

B12 (also known as Cobalamin) protects your nerves and plays a role in the development of red blood cells. It's crucial for oxygen transport throughout your body and, if deficient, can lead to heart and lung problems. Inadequate levels of vitamin b12 are also linked to cognitive impairment, fatigue, memory loss, shortness of breath, loss of appetite, and impaired vision.

Vitamin B12

How Much Vitamin B Do You Need?

“Normal” vitamin B12 varies throughout our lives. Most people fall within the 160 to 950 picograms per milliliter, which is a wide range. The important number is the lower number. If you fall below 160 pg/mL, it’s cause for concern.

There are several reasons why you might have low vitamin B12 levels, including:

  • Not eating enough foods high in vitamin B12 (usually only an issue for vegans or vegetarians)
  • Lack of the protein that helps your body absorb vitamin b12
  • Hyperthyroidism
  • Pregnancy

In rare instances, usually only when someone has liver disease or myeloproliferative disorders, are vitamin B12 levels too high. Most people pass anything their body doesn’t use through their urine.

If you have only a mild vitamin b deficiency, dietary changes might be enough to resolve the problem. Foods that are high in vitamin b include:

  • Organ meat, especially liver and kidneys
  • Beef
  • Clams, tuna, trout, salmon
  • Sardine
  • Fortified cereals
  • Fortified nutritional yeast
  • Milk and other dairy products
  • Eggs

Symptoms of vitamin B12 deficiency

If you're experiencing any of the following symptoms, it may be a sign that your body doesn't have enough vitamin B12.

  • A pale yellow hue to the skin
  • Glostitis or inflammation of the tongue. The tongue may change color, swell in size and develop an unusual appearance on its surface.
  • Lethargy: a state of weariness that involves reduced mental capacity, energy, and motivation)
  • Feeling faint: a feeling of lightheadedness with the sensation that you may pass out without really losing consciousness.
  • Palpitations: a sensation that the heart is pounding, fluttering, racing, or skipping a beat. You may feel it in your throat, chest, or neck.
  • Weight loss and reduced appetite.

Why Would Your Doctor Order a Vitamin B Test?

If you’re experiencing any of the following symptoms, your doctor might order that your vitamin B levels be tested. This can happen before or after other issues are ruled out as causes.

  • Fatigue
  • Weight Loss
  • Numbness or Tingling
  • Irritability
  • Mood Changes
  • Depression
  • Skin Issues
  • Muscle Pain
  • Joint Pain
  • Brain Fog

It’s also common to undergo a vitamin b12 test if your doctor suspects you have pernicious anemia. This occurs when your body isn’t able to absorb vitamin b12 from the foods you eat. No matter how careful you are with your diet, if your body can’t use what you are putting in it, it’s of no use to you.

A vitamin b12 test is also ordered because the patient is exhibiting certain nervous system issues, such as tingling, numbness, or weakness in the limbs, or is experiencing issues with balance.

Why Is It Important to Test Vitamin B12 Levels?

As mentioned at the start of this article, as many as 46% of adults aged 30 to 70 are deficient in vitamin B12 – that's a significant percentage. The problem has largely been overlooked for decades by healthcare team members and physicians, and it is worrying because low levels cause several psychiatric and neurologic problems.

B12 deficiency has been primarily underplayed in healthcare and ignored in favor of more recognizable and more costly diagnoses. This approach has led to malpractice and substandard care, which have cost many individuals their health and wasted billions in health care dollars.

In addition to just not feeling your best, inadequate vitamin B levels also put you at risk of:

  • Excessive bleeding
  • Lightheadedness
  • Fainting
  • Difficulty finding veins to draw blood
  • Hematoma (bruising)
  • Infection

Does an At-Home Vitamin B Test Provide Reliable Results?

Yes. At-home tests for vitamin B are finger-prick tests, which means you prick your finger for a small blood sample and send that sample to a lab for testing. Reputable testing companies have an independent board-certified physician review your results and report those results back to you.

It's important to schedule an appointment with your doctor to review the results, especially if anything seems abnormal about them.

Even if your test results from an at-home vitamin B test fall within the normal range, you can use the information you’ve collected along the way to make healthier lifestyle choices. 

As you age, it becomes a greater struggle to maintain healthy vitamin and nutrient levels. Monitoring your levels is a great first step toward feeling your best throughout your life.

We recommend EverlyWell for at home B12 Testing.

Things to consider before getting a B12 blood test

You can have the test anytime. There's no need for special preparations like fasting. In fact, your doctor may add it to the test that assesses your glucose and cholesterol levels. That said, you should always tell your physician about any supplements or medications you're taking before the test is administered.

When Should I See My Doctor about Vitamin B12 Levels?

Some people have inadequate vitamin b12 levels and don’t even realize it. The signs tend to be subtle. They might not feel their best, but it’s been so long since they were feeling optimal they don’t recognize an issue. 

Some people attribute symptoms linked to vitamin b12 deficiencies to aging or skipping the gym or indulging too much in their diet. And in some cases, these are linked to why their vitamin b12 levels are off, but they don’t realize their choices have led to a vitamin deficiency.

Depending on your age and your overall health, it’s a good idea to have vitamin levels tested periodically unless you feel perfect every day. If you are experiencing any of the symptoms listed above, you should speak to your doctor. If he or she doesn’t mention vitamin b12, bring it up and ask for the test. This is an especially good idea if you’ve added a few of the foods that are high in vitamin b12 to your diet recently and you haven’t noticed any changes.

If you prefer not to go right to your doctor, try the at-home test and take the next step based on your results.

Treating a Vitamin B12 deficiency

In most scenarios, vitamin b12 deficiency is quickly treated with intravenous medications or oral tablets that replace the missing vitamins.

The supplements are commonly administered by injection in the beginning. Then, based on whether your deficiency arises from your diet, you may need to swallow tablets between meals. These treatments may be necessary for the rest of your life.

In some situations, changing your diet will address the deficiency and prevent its reemergence. Assuming your body is capable of processing it, you can get vitamin B12 from fish, eggs, meat, yeast, and fortified foods.

If your physician chooses to give you injections, they'll likely use hydroxocobalamin, as it is the most dependable, particularly if you are suffering any neurologic symptoms. It is a better alternative to cyanocobalamin, as it offers better retention, greater availability, and it does not need declaration. Hydroxocobalamin does not cost more than cyanocobalamin, and it is readily accessible.


Vitamin B12 is crucial for proper bodily function, so you should have frequent blood tests to ensure you have enough. If your test results report optimal levels, there's no need to do anything but eat a balanced diet. However, if your levels are low, you'll need to supplement your diet with injections or oral supplements.

Cheap DNA Kits (all under $60). Read our 2021 Guide.

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“Vitamin B12 Level: MedlinePlus Medical Encyclopedia.” Medlineplus.Gov,

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