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Vitamin B12 Blood Test

Updated on March 24, 2022
Medically Reviewed by
Dr. Dhingra
Written by
Kelly Jamrozy
6 sources cited
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Vitamin B12, also called cobalamin, is a very important B vitamin. It plays a major role in the health of nerve tissues and brain functions. 

Additionally, vitamin B12 works together with vitamin B9, also known as folic acid or folate. These two help each other in making red blood cells.

Red blood cells are crucial for oxygen transport throughout the body and if deficient, can lead to heart and lung problems. 

Vitamin B12 and folate also produce S-adenosylmethionine (SAMe), a compound involved in mood regulation and immune function.

Cobalamin deficiency is dangerous because it can lead to irreversible damage to the brain and nervous system. Inadequate levels of vitamin B12 are also linked to cognitive impairment, fatigue, memory loss, shortness of breath, loss of appetite, and impaired vision.

To ensure healthy Vitamin B12 levels, a vitamin B12 blood test can be helpful.

Vitamin B12 Blood Test 3

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How Much Vitamin B12 Does Your Body Need?

“Normal” vitamin B-12 levels vary depending on factors like age and sex. Pregnant and lactating women will also have different vitamin B12 needs. 

The National Institutes of Health (NIH) recommends Americans to take 2.4 micrograms of Vitamin B12 per day.

How much vitamin B12 is too much?

Most doctors agree that vitamin B12 can be safely taken in higher doses. This is because vitamin B12 is water-soluble.

Water-soluble vitamins dissolve in water when consumed. The body does not store excess amounts of these vitamins and excretes them through urine.

If the kidney function is impaired, this can cause vitamin B12 to build up in the bloodstream. A study published in the Journal of the American Medical Association (JAMA) suggests that elevated levels of vitamin B12 is associated with a higher risk for death.

Vitamin B12 deficiency

The vitamin can be sourced from supplements and animal sources such as fish, meat, poultry, eggs, and dairy products.

Problems can arise when the body doesn't get enough vitamin B12. If you have a vitamin B12 deficiency, it may be caused by:

  • Not eating enough foods rich in vitamin B12
  • Lack of the protein that helps your body absorb vitamin B12
  • Hyperthyroidism or overactive thyroids
  • Pregnancy

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 
  • Glossitis 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 is Vitamin B12 Deficiency a Serious Concern?

As many as 46% of adults aged 30 to 70 are deficient in vitamin B12 – that's a significant percentage. If it isn't treated, it can put you at risk for:

  • Dementia
  • Psychiatric illness
  • Anemia
  • Blood clots
  • Impaired immunity
  • Bone marrow failure
  • Heart failure
  • Vision problems
  • Memory loss
  • Paresthesia or "pins and needles"
  • Ataxia or loss of physical coordination
  • Loss of sensation on the extremities
  • Infertility
  • Stomach cancer
  • Birth defects (e.g., spina bifida)

Neurological problems and birth defects that result from a lack of vitamin B12 are irreversible. Treating it as soon as possible prevents complications.

Does an At-Home Vitamin B12 Test Provide Reliable Results?

Yes. 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.

To reduce the health risks associated with low levels of vitamin B12, consider taking at-home vitamin B12 tests.

  • EverlyWell’s B Vitamins Test helps identify deficiencies in vitamins B6 (pyridoxine), B9 (folic acid/folate), and B12 (cobalamin).
  • LetsGetChecked Essential Vitamins Test check for a wider range of vitamins, including vitamins B12 (cobalamin), vitamin D, and vitamin E (alpha-tophocerol). Use the code "YOURDNA" at checkout to get 30% off.
Vitamin B12 Blood Test 4

EverlyWell - B12 Vitamin Test

EverlyWell’s B12 Test will tell you if your vitamin B levels are abnormal. It will then give you some steps you can take to get them back into balance.

Why Would Your Doctor Order a Vitamin B12 Test?

If you're experiencing any of the following signs and symptoms, your doctor might order a vitamin B12 test.

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

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.

Things to Consider Before Getting a Vitamin B12 Blood Test

You can have the test anytime.

There's no need for special preparations like fasting.

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.

Depending on your age and your overall health, it's a good idea to have vitamin levels tested periodically. If you are experiencing any of the symptoms listed above, you should speak to your doctor. If they don’t mention vitamin B12, bring it up and ask for the test. 

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 Vitamin B12 Deficiency

If you have only a mild vitamin B12 deficiency, dietary changes might be enough to resolve the problem. Eat foods that are high in vitamin B12, such as:

  • Organ meat, especially liver and kidneys
  • Beef
  • Pork
  • Lamb
  • Poultry
  • Ham
  • Tuna
  • Haddock
  • Fortified cereals
  • Fortified nutritional yeast
  • Milk, yogurt, cheese, and other dairy products
  • Eggs

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.

If your physician chooses to give you injections, they'll likely use hydroxocobalamin.

Conclusion

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.

Resources

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  1. "Association of Plasma Concentration of Vitamin B12 With All-Cause Mortality in the General Population in the Netherlands." JAMA Network.
  2. "Vitamin B12: Fact Sheet for Health Professionals." National Institutes of Health Office of Dietary Supplements.
  3. "Vitamin B12 and Cognitive Function." National Center for Biotechnology Information.
  4. Vitamin B12 Level: MedlinePlus Medical Encyclopedia.” Medlineplus.
  5. "Vitamin B12." Oregon State University.
  6. "Vitamin B12 or folate deficiency anaemia: Complications." National Health Service UK.
Dr. Dhingra
Dr. Harshi Dhingra
Medical Reviewer
Dr Harshi Dhingra is a licensed medical doctor with a specialization in Pathology. Dr. Dhingra has of over a decade in diagnostic, clinical, research and teaching work, including managing all sections of Pathology laboratory including histopathology, cytology, hematology and clinical Pathology.
Kelly Jamrozy
Kelly Jamrozy
Content Contributor
Kelly has experience working with clients in a variety of industries, including legal, medical, marketing, and travel. Her goal is to share important information that people can use to make decisions about their health and the health of their loved ones. From choosing the best treatment programs to improving dental and vision health to finding the best method for helping anyone who is struggling with health issues, she hopes to share what she learns through informative content.
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