Vitamin B-12 is necessary for several bodily processes, including nerve function and the production of DNA and red blood cells.
A person whose vitamin B-12 levels are outside of the normal range will require treatment. Low levels of the vitamin can cause neurological symptoms, as well as fatigue, constipation, and weight loss. High B-12 levels may indicate liver disease, diabetes, or another condition.
Read on to learn more about testing B-12 levels and what the test results mean.
Why is a vitamin B-12 level test useful?
The vitamin B-12 level test checks how much vitamin B-12 is in the body. The results can help doctors to determine if abnormal vitamin B-12 levels are causing symptoms.
A doctor may order a vitamin B-12 level test if a person has any of the following:
Suspected vitamin B-12 deficiency
Researchers believe that up to 15 percent of Trusted Source of people in the United States have a vitamin B-12 deficiency. Signs and symptoms of deficiency include:
- difficulty maintaining balance
- fast heartbeat
- numbness and tingling in the hands and feet
- poor memory
- a sore mouth or tongue
Infants with vitamin B-12 deficiency may fail to thrive. They may experience movement problems in addition to delayed development.
People with symptoms of pernicious anemia may also need a vitamin B-12 level test. Pernicious anemia, which causes low levels of red blood cells, results from an inability to absorb vitamin B-12.
It often affects older adults or those who are lacking intrinsic factors. An intrinsic factor is a substance in the stomach that binds to vitamin B-12 so that the body can absorb it.
Symptoms of pernicious anemia include:
- loss of appetite
- pale skin
- weight loss
High serum folate levels
Serum folate is the level of folic acid in the blood. High serum folate levels can mask Trusted Source the symptoms of vitamin B-12 deficiency and make its neurological symptoms worse.
They can also increase the likelihood of anemia.
Symptoms of other conditions
An abnormally high vitamin B-12 status can be an early sign of liver disease, diabetes, or certain types of leukemia. A doctor may use the results of a vitamin B-12 test to help form their diagnosis.
Risk factors for low vitamin B-12 levels
Certain people are more at risk of vitamin B-12 deficiency than others, especially those who have low stomach acid or other digestive issues. Stomach acid separates vitamin B-12 from food so that the body can absorb it more efficiently.
The following groups of people are more likely than others to experience low vitamin B-12 levels:
- older adults
- vegans and vegetarians
- people with diabetes
- people with conditions that reduce vitamin B-12 absorption, including celiac disease and Crohn’s disease
- people who have had gastric bypass surgery
- those who are breast-feeding
- people who are taking medicines such as chloramphenicol, proton pump inhibitors, or H2 blockers
How does the vitamin B-12 level test work?
Doctors usually use a blood test to check vitamin B-12 status, but home urine tests are also available. A doctor can check vitamin B-12 as part of a standard blood test.
Although it is not necessary to fast before a B-12 test, a person may need to if the doctor is also using the test to look at other components in the blood.
It is important that individuals tell their doctor about any medications and supplements they are taking, as some can affect the results.