The vitamin B12 test may be ordered as part of other tests that help in the diagnosis of anemia like megaloblastic anemia, help in the diagnosis of CNS disorders, and evaluate of malabsorption syndromes.

The result of vitamin B12 test help to assess the general health and nutritional status if appear signs and symptoms of malnutrition or dietary malabsorption, and also monitor the effectiveness of treatment with vitamin B12 supplements.

A Healthcare provider may recommend a vitamin B12 test if there any symptoms like numbness or tingling in the arms and legs, weakness, and loss of balance.

Moreover, there are other conditions that may also the health provider recommend to do a vitamin B12 test like sudden severe confusion (delirium), loss of brain function (dementia) due to metabolic causes, and nerve abnormalities like peripheral neuropathy.

The vitamin B12 test does not need any preparation steps by the patient. Besides, the patient should tell the healthcare provider about all of the drugs or supplements in use, since certain drugs may affect the result.

Reference values

*Normal ranges may vary from one lab to another due to several factors, so it is important to discuss test results with a doctor.

Interpretation :

The level of vitamin B12 is decreased due to abnormalities of cobalamin transport or metabolism, bacterial overgrowth, and the presence of parasite like Diphyllobothrium (fish tapeworm) as well as due to Intestinal malabsorption and Intrinsic factor deficiency.

 Furthermore, vitamin B12 decreases in several situations because it related to dietary deficiency or poor absorption like Crohn’s disease, gastric or small intestine surgery, hypochlorhydria, inflammatory bowel disease, late pregnancy, and Pernicious anemia.

On the other hand, a high concentration of vitamin B12 in the body occurs due to some diseases like chronic granulocytic leukemia, chronic obstructive pulmonary disease, chronic renal failure, diabetes, obesity, leukocytosis, polycythemia vera, severe congestive heart failure as well as liver cell damage (when hepatocyte released their stored vitamin B12 after its destruction), and also protein malnutrition (because of lack of transport proteins). Moreover, Ingesting estrogens, vitamin C or vitamin A can also cause high B12 levels.

There are many drugs effects on the levels of vitamin B12 in the body, for example, chloral hydrate increase the level of vitamin B12 while the following drugs decreasing level of vitamin B12: alcohol, aminosalicylic acid, anticonvulsants, ascorbic acid, cholestyramine, cimetidine, colchicine, metformin, neomycin, oral contraceptives, ranitidine, and triamterene. 

A vitamin B12 test is performed by drawing a blood sample from the patient’s arm of (1mL) volume. Sometimes, a random urine sample is required. The method most probably used is immunochemiluminescent assay.

Usually, the most common Vitamin B12 deficiency occurs as a result of not getting sufficient amounts of vitamins through the diet or supplements that meet the needs of the body.

Depending on the underlying causes of vitamin B12 deficiency the treatment is applied by taking supplements or vitamin B12 injections especially for people who lack intrinsic factors or have conditions causing general malabsorption. 

Vitamin B12 testing may be ordered on a regular basis when people treated for malnutrition or a B12 deficiency, and when they have signs and symptoms of vitamin B12 deficiency.

In addition, the healthcare provider may be ordered the methylmalonic acid (MMA) test if the patient has normal vitamin B12 level and clinical symptoms of vitamin B12 deficiency.

Vitamin B12 is one of the vitamin B complex that is important for many body functions, such as DNA synthesis; formation of normal red blood cell (RBC) and white blood cell (WBC), central nervous system (CNS) integrity and repair of tissues and cells.

There are many reasons for vitamin B12 deficiency such as deficiency of Intrinsic factor (IF), lack of gastric acid, and malabsorption in the small terminal ileum. 

The vitamin B12 test may be ordered as part of other tests that help in the diagnosis of anemia like megaloblastic anemia, help in the diagnosis of CNS disorders, and evaluate of malabsorption syndromes.

Vitamin B12 decreases in several situations because it related to dietary deficiency or poor absorption like Crohn’s disease, gastric or small intestine surgery. While occurs vitamin B12 increases due to some diseases like chronic granulocytic leukemia, chronic obstructive pulmonary disease, chronic renal failure, diabetes, and obesity.

There are many drugs effects on the levels of vitamin B12 in the body, for example chloral hydrate, aminosalicylic acid, anticonvulsants, and ascorbic acid.

The treatment of vitamin B12 deficiency is applied based on the underlying causes by taking nutritional supplements or vitamin B12 injections.