Version July 2025
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What are vitamin B12 and folate blood tests? —
These are tests to check the levels of 2 different vitamins in the blood: vitamin B12 and folate (also called "folic acid").
These vitamins help the body work normally:
●Vitamin B12 is found in foods that come from animals, including eggs, meat, poultry, and fish. The body needs vitamin B12 to make new blood cells, such as red blood cells, white blood cells, and platelets. It also needs vitamin B12 for the nervous system to work normally.
●Folate is found in dark green, leafy vegetables. It is also added to many grains and cereals. The body needs folate to make new cells. Folate is very important for people who might get pregnant. That's because it is needed for a baby to develop normally, especially during the first few weeks of pregnancy.
When a person does not have enough of a vitamin the body needs, it is called a "deficiency." People can have vitamin B12 deficiency, folate deficiency, or both.
Why might I get a vitamin B12 or folate blood test? —
Your doctor might order 1 or both of these tests:
●If you have symptoms of vitamin B12 or folate deficiency – Having too little of these vitamins can make you feel tired. Vitamin B12 deficiency can also cause tingling or numbness in the hands or feet, trouble walking, mood changes, or problems with thinking or memory.
●If you are at risk for vitamin B12 or folate deficiency – Things that increase your risk include not eating enough foods with these vitamins in them, taking certain medicines, and having a condition where your body cannot absorb or use vitamins normally. These are more common for vitamin B12 deficiency. Folate is added to many grains and cereals, so most people get enough through their diet. People who drink alcohol and do not eat a balanced diet can sometimes get folate deficiency.
●To help find the cause of anemia – Anemia is when you have too few red blood cells. This most often happens if you do not have enough iron. It can also happen if you do not have enough vitamin B12 or folate.
How do I prepare for a vitamin B12 or folate blood test? —
You need to get a "blood draw." Your doctor or nurse will tell you where to go for this.
It might help to wear a short-sleeve shirt to your blood draw appointment. This makes it easier for the person drawing your blood to get to your arm.
What happens during a blood draw? —
A needle is used to take a small amount of blood from your arm (figure 1). Collecting the blood only takes a few minutes. The blood is then tested in a lab.
Tell the person who takes your blood:
●If you take "blood thinner" medicines or have a bleeding problem – They will make sure your bleeding is under control before you leave.
●If you have a latex allergy – Some of the supplies used for blood draws might contain latex.
●If you have a preferred arm to use
Most of the time, getting blood taken does not cause problems. You might have a little soreness or bruising where the needle went in.
What do my results mean? —
Your doctor or nurse will tell you when to expect your results, and will contact you with the results. Or if you use an online "patient portal," you might get an alert there when your results are ready.
If your vitamin B12 or folate level is low, your doctor or nurse will talk to you about what to do next. They might need to do more tests to figure out the cause. You will probably need to take vitamin supplements.
If you do have a health problem, your doctor will work with you to come up with a plan for treatment.
Patient education: Vitamin B12 deficiency and folate deficiency (The Basics)
Patient education: Vegetarian or vegan diet (The Basics)
Patient education: Evaluating memory and thinking problems (The Basics)
Patient education: Pernicious anemia (The Basics)
Patient education: Vitamin supplements (The Basics)
