Test Details: Vitamin B12 is an essential vitamin found in food products such as meat, fish, milk and dairy products. In the body, Vitamin B12 is required for the function and development of important body parts including nerves, blood cells. Deficiency of Vitamin B12 and folic acid can lead to megaloblastic anemia This test is done when an individual presents with signs and symptoms of anemia such as weakness, fatigue, loss of appetite, dementia, increased heart beat, numbness, tingling sensation, etc.