Why am I having this Vitamin B12 Test?

Vitamin B12 and folate (folic acid) are both B vitamins that are needed to make red blood cells and to keep your nervous system healthy. Vitamin B12 is found in foods such as meats, eggs, dairy products, and fish. Folate is found in fruits, beans, and leafy green vegetables. These vitamins also get added to some foods, such as grains and cereals.

You may have a lack (deficiency) of these B vitamins in your body if you do not get enough of them in your diet. Low levels can also be caused by digestive system diseases that interfere with your ability to absorb the vitamins from your food. The most common cause of a vitamin B12 deficiency is the inability to absorb it (pernicious anemia).

You may have a vitamin B12 and folate test if:

• You have symptoms of vitamin B12 or folate deficiency, such as fatigue, headache, confusion, poor balance, or tingling and numbness.
• You are pregnant or breastfeeding. Women who are pregnant or breastfeeding need more folate and may need to take supplements.
• Your red blood cell count is low (anemia).
• You are an older person and have mental confusion.
• You have a disease or condition that may lead to a deficiency of these B vitamins.

What is being tested?

This test measures the amount of vitamin B12 and folate in your blood. The tests for vitamin B12 and folate may be done together or separately.

What kind of sample is taken?

A blood sample is required for this test. It is usually collected by inserting a needle into a blood vessel.

How do I prepare for this test?

Follow instructions from your health care provider about eating and drinking before the test.

Tell a health care provider about:

• All medicines you are taking, including vitamins, herbs, eye drops, creams, and over-the-counter medicines.
• Any medical conditions you have.
• Whether you are pregnant or may be pregnant.
• How often you drink alcohol.

How are the results reported?

Your test results will be reported as values that identify the amount of vitamin B12 and folate in your blood. Your health care provider will compare your results to normal ranges that were established after testing a large group of people (reference ranges). Reference ranges may vary among labs and hospitals. For this test, common reference ranges are:

• Vitamin B12: 160–950 pg/mL or 118–701 pmol/L (SI units).
• Folate: 5–25 ng/mL or 11–57 nmol/L (SI units).

What do the results mean?

Results within the reference range are considered normal. Vitamin B12 or folate levels that are lower than the reference range may be caused by various conditions, including:

• Anemia.
• Poor nutrition.
• Alcoholism.
• Liver disease.
• Digestive disease.

High levels of vitamin B12 are rare, but they may happen if you have:

• Cancer.
• Diabetes.
• Heart failure.
• Obesity.
• Liver disease.
• Human immunodeficiency virus (HIV).

High levels of folate may happen if:

• You have pernicious anemia.
• You are vegetarian.
• You have had a recent blood transfusion.

Talk with your health care provider about what your results mean.

Questions to ask your health care provider

Ask your health care provider, or the department that is doing the test:

• When will my results be ready?
• How will I get my results?
• What are my treatment options?
• What other tests do I need?
• What are my next steps?

Summary

• Vitamin B12 and folate (folic acid) are both B vitamins that are needed to make red blood cells and to keep your nervous system healthy.
• You may have a lack (deficiency) of these B vitamins in your body if you do not get enough of them in your diet or if you have a digestive system disease.
• This test measures the amount of vitamin B12 and folate in your blood. A blood sample is required for the test.
• Talk with your health care provider about what your results mean.