Test Details


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Vitamin B12 (Cyanocobalamin), Serum

Number of parameters covered 2


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Synonyms/Also Known as


Related tests

Complete Blood Count, Methylmalonic Acid, Homocysteine, B Vitamins, Intrinsic Factor Antibody, Parietal Cell Antibody, Reticulocyte Count, Blood Smear

Why get tested?

To diagnose a case of anemia or a case of neuropathy, to evaluate the nutritional status of an individual and to monitor the effectiveness of treatment in vitamin B12 or folate deficiency.

When to get tested?

When complete blood picture (CBP) is abnormal with the blood smear showing macrocytosis (presence of large red blood cells) or hypersegmented neutrophils. When there are symptoms of anemia such as weakness, tiredness, pale skin and/or symptoms of neuropathy such as tingling sensations, eye twitching, memory loss, altered mental status. To monitor the treatment for vitamin B12 or folate deficiency.

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Test preparation needed

No special preparation required

About The Test

How is it used
Vitamin B12 and folate tests are often used together to detect vitamin deficiencies and pernicious anemia, which is an autoimmune disorder that affects B12 absorption. Vitamin B12 and folate are the two vitamins that must be supplied in the diet as they ca ot be produced in the body. B12 and folate are essential for formation of RBCs, tissue and cell repair, DNA synthesis. Vitamin B12 is also essential for proper nerve functioning. B12 and folate tests may also be ordered to evaluate an elderly individual with an altered mental state or other behavioral changes. A B12 test may be ordered either alone or in combination with folate, other laboratory tests such as a complete blood picture (CBP), antinuclear antibody (ANA), C-reactive protein (CRP) and rheumatoid factor (RF) etc, to help determine the cause of neuropathy. Vitamin B12 may also be used to evaluate the nutritional status of a person with signs and symptoms of significant malnutrition or dietary malabsorption, which includes people with alcoholism, liver disease, gastric cancer, celiac disease, inflammatory bowel disease, or cystic fibrosis. Vitamin B12 along with folate is also helpful in monitoring the effectiveness of treatment in B12 and folate deficiencies. Other laboratory tests like homocysteine and methylmelonic acid (MMA) are useful to help detect B12 and folate deficiencies. The levels of Homocysteine and MMA are elevated in B12 deficiency. But in folate deficiency only homocysteine levels are elevated. This aspect is important because giving folate to a B12-deficient individual will only correct the anemia and not the irreversible neurological damage.


1. Is excess vitamin B12 and folic acid supplements harmful?

No. B12 and folic acid are water-soluble and any excess levels will be excreted in urine. However, taking folic acid can mask vitamin B12 deficiency, so it is important to test for both vitamin B12 and folate levels, before starting folate supplementation.

2. Is it necessary to have vitamin B12 and folate levels tested routinely?

Vitamin B12 and folate levels are not tested routinely unless symptoms associated with a deficiency, large red blood cells (RBCs) in a complete blood picture (CBP), and conditions associated with malabsorption are seen.

3. Are folate levels tested in pregnancy?

Folate levels may be tested in some cases during pregnancy. Folate supplementation is however recommended routinely for women before and during pregnancy.