Folate, also known as vitamin B-9 and cobalamin, vitamin B-12, are members of the vitamin B complex family. Vitamin B-12 and folate are necessary for the proper functioning of the human body. Although both vitamins are water-soluble, the body can store vitamin B-12 for up to five years and folate for several months. So, a B-12 or folate deficiency reflects a chronic shortage of one or both of these vitamins. A blood test is used to assess the levels of vitamin B-12 and folate in your body.
Vitamin B-12
Vitamin B-12 is unique in that it contains cobalt, a metal ion. It is required for the metabolism of macronutrients, red blood cell formation, neurological function, DNA synthesis and the maintenance of the central nervous system. The recommended dietary allowance for individuals over the age of 14 is 2.4 mcg of vitamin B-12 each day. Vitamin B-12 is naturally found in animal products such as eggs, meat, poultry, shellfish, fish, eggs and dairy. It is also available in fortified cereals, dietary supplements and medications.
Folate
Folate is the B vitamin that naturally occurs in food, while folic acid is the synthetic form found in supplements or added to fortified foods. Folate is abundant in leafy green vegetables such as spinach, kale and broccoli. Dried beans and peas, other vegetables, citrus fruits and fortified grains are also good sources of folate. The Food and Nutrition Board at the Institute of Medicine established dietary folate equivalents to help account for the differences between folate and the more bioavailable folic acid. People over the age of 14 require 400 mcg of folate per day. Pregnant women need 600 mcg and lactating women 500 mcg of folate each day. Folate helps maintain new cells, promote tissue growth, produce RNA and red blood cells, prevent unwanted changes to DNA, metabolize homocysteine and treat anemia. Folate is known for its ability to prevent neural tube defects when taken during pregnancy.
The Test
A chronic shortage of vitamin B-12 or folate in the body can lead to macrocytic anemia, a condition in which the body does not have enough healthy red blood cells to carry oxygen to its tissues. A B-12 and folate blood test is primarily ordered to help your physician diagnose a deficiency and determine the cause of macrocytic anemia. It is typically ordered as a follow-up after you have had an abnormal complete blood count, indicating you have large red blood cells and a decreased hemoglobin concentration. It is also used when you have a known B-12 or folate deficiency to monitor the effectiveness of your treatment.
Normal Levels
Normal vitamin B-12 levels are 200 to 900 pg/mL. The normal range for folate is 2.7 to 17.0 ng/mL. If your results fall within these ranges, you have adequate vitamin B-12 and folate stores. This means that your red blood cells are healthy and able to carry oxygen throughout your body. It is important to talk with your physician about your results because normal levels vary slightly from laboratory to laboratory.
What Abnormal Results Mean
Elevated B-12 and folate levels are uncommon. Values less than 200 pg/mL indicate a vitamin B-12 deficiency. Similarly, levels below 1.7 ng/mL indicate a folate deficiency. If you are deficient in either vitamin B-12 or folate, you will most likely experience anemia-related symptoms, such as weakness, shortness of breath, lightheadedness, nerve damage, tingling and numbness in the extremities, confusion, irritability, dementia and varying degrees of neuropathy. A vitamin B-12 and folate test will indicate the presence of deficiencies, but they do not reflect the severity of the anemia associated with the deficiency.
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