Vitamin B-12 is a fat-soluble vitamin required for several crucial biochemical processes in the body, including neuronal firing, red blood cell synthesis and DNA replication. A deficiency in vitamin B-12 can cause several symptoms, which may result in severe health problems. If your doctor suspects you have a vitamin B-12 deficiency, a blood test is available to determine how much of this vitamin is present in your bloodstream.
Vitamin B-12 Level
The normal concentration of vitamin B-12 in the blood ranges from around 170 picograms per milliliter, or pg/ml, to 900 pg/ml, reports the Office of Dietary Supplements of the National Institutes of Health. In adults, levels below 170 pg/ml are typically considered an indication of vitamin B-12 deficiency.
Vitamin B-12 Blood Test
The standard test of vitamin B-12 levels requires drawing blood from a vein, usually at on the back of the hand or the inside of the elbow. Before taking the test, you will need to not eat or drink anything for 6 to 8 hours. Be sure to tell your doctor about any medications your are taking, including herbal and over-the-counter medications, because certain medications may affect the test results.
Blood Levels Versus Intracellular Levels
The most common tests of vitamin B-12 levels measure the concentration of vitamin B-12 in the blood serum or blood plasma, two different components of blood. However, levels of vitamin B-12 in the blood may not accurately reflect the levels of the vitamin within actual cells. While there are other tests that indirectly measure levels of vitamin B-12 within cells, they are not entirely accurate for other reasons. As a result, the blood test is still the standard test for measuring vitamin B-12 levels.
Recommended Dietary Allowance
The Food and Nutrition board of the Institute of Medicine has developed a Recommended Dietary Allowance, or RDA, for vitamin B-12. Based on available research, consuming the RDA each day should prevent low levels of vitamin B-12 from developing. For adults ages 14 years and older, the RDA for vitamin B-12 is 2.4 mcg per day. The RDA decreases with age for children, down to 0.4 mcg per day for infants less than 6 months old.
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