Vitamin b12 test

This blood test measures the amount of vitamin B12 in your child's blood. The body needs this vitamin to make blood cells and to keep the nervous system healthy.

A vitamin B12 test is used to:

• Check for vitamin B12 deficiency anemia. There are several risk factors for this anemia, such as those who have had stomach or intestinal surgery, small intestine problems, or people with a family history of this anemia.
• Diagnose the cause of certain types of anemia, such as megaloblastic anemia.
• Help find the cause of a decrease in mental abilities or other nervous system symptoms, such as tingling or numbness of the arms or legs (peripheral neuropathy).
• See if vitamin B12 deficiency anemia is present after a person has been diagnosed with atrophic gastritis.

Your health professional drawing blood will:

• Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
• Clean the needle site with alcohol.
• Put the needle into the vein. More than one needle stick may be needed.
• Attach a tube to the needle to fill it with blood.
• Remove the band from your arm when enough blood is collected.
• Put a gauze pad or cotton ball over the needle site as the needle is removed.
• Put pressure on the site and then put on a bandage.

You may need to fast for 8 hours before the test. Your doctor may give you some specific instructions.

Each lab has a different range for what’s normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn’t in the normal range may still be normal for you.

High values

• High levels of vitamin B12 can occur in liver disease (such as cirrhosis or hepatitis) and some types of leukemia. But the vitamin B12 test is not usually used to diagnose these problems.
• In rare cases, high levels may be found in people with diabetes or who are obese.

Low values

• Low levels of vitamin B12 may mean you have vitamin B12 deficiency anemia, which might be caused by problems with the absorption of the vitamin (such as pernicious anemia).
• Low levels may also occur following removal of part or all of the stomach (gastrectomy), gastric bypass surgery, or gastric stapling surgery, or following surgery to remove part of the small intestine where this vitamin is absorbed (terminal ileum).
• Low levels may mean an infection with a parasite called fish tapeworm is present.
• In rare cases, low levels may mean a person is not getting enough vitamin B12 in his or her food.
• Low levels are linked with hyperthyroidism or folate deficiency anemia.
• High levels of protein in the blood, such as from multiple myeloma, can falsely decrease blood vitamin B12 levels.