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Vitamin B12

What is it?

Vitamin B12 is found in the body and can be measured with a blood test. Vitamin B12 levels in the blood may be used to help find the cause of anemia (uh-nee-mee-uh). Anemia is a condition where there are fewer red blood cells than normal. Vitamin B12 levels also may be used to evaluate malnutrition.

Why do I need it?

  • A vitamin B12 level may be done if your complete blood count (CBC) shows anemia and larger than normal size red blood cells. A folic acid test is often done at the same time as the vitamin B12 test. Ask your caregiver for the CareNotes™ handout about folic acid.
  • Several conditions may cause lower than normal vitamin B12 levels. One common cause is the intestines are not able to absorb vitamin B12. Some symptoms along with the anemia may be weakness, tingling, and numbness. The main sources of vitamin B12 are meat, eggs, and dairy products. Strict vegetarians may be at risk for low vitamin B12 levels. Caregivers will explain the test and why you need it.

How do I get ready for the test?

Your caregiver will tell you when to have your blood test done. Do not eat or drink anything, except water, for at least 8 hours before the test. Do not drink any alcoholic beverages before the test. You may need to stop taking some medicines before the test. Ask your caregiver if you should wait until after your blood is taken to take your normal medicines.

How is the specimen collected?

A caregiver will put a wide rubber strap around your arm and tighten it. Your skin will be cleaned with alcohol. A small needle attached to a special test tube will be put into a vein in your arm or hand. The tube has suction to pull the blood into it. When the tube is full, the rubber strap, needle and tube are removed. The caregiver will press a piece of cotton where the needle was removed. You may be asked to hold the cotton on the site for a few minutes to help stop the bleeding. Tape may then be put over the cotton on your arm.

What do I do after the test?

You may remove the tape and cotton in about 20 to 30 minutes. Call your caregiver to get the results of your test. Your caregiver will explain what your test results mean for you. Follow the instructions of your caregiver.

Care Agreement

You have the right to help plan your care. To help with this plan, you must learn about your lab tests. You can then discuss the results with your caregivers. Work with them to decide what care may be used to treat you. You always have the right to refuse treatment.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.