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What Is the B12 Blood Test?
Vitamin B12, also known as cobalamin, is a nutrient that is vitally important to the creation of DNA and to the overall function of the nervous system. A lack of vitamin B12 in the body can lead to vitamin deficiency anemia 124. A simple blood test can be performed in your doctor’s office to test the levels of vitamin B12 in your blood. Once the test is performed, your doctor will discuss the results with you.
Indications
Your doctor may order a vitamin B12 test to be performed if you have symptoms indicating a deficiency. Elderly patients may exhibit signs of a deficiency that include sudden behavior changes, including depress, irritability and confusion. Other signs and symptoms include fatigue, general weakness, dizziness and a sore mouth. Tingling or burning in your hands and feet indicate neuropathy and could be caused by a lack of vitamin B12. If you’ve recently had a complete blood count performed, your doctor may order a B12 test if the results indicated an abnormality in your red blood cells, or an abnormally low hemoglobin count.
- Your doctor may order a vitamin B12 test to be performed if you have symptoms indicating a deficiency.
- Elderly patients may exhibit signs of a deficiency that include sudden behavior changes, including depress, irritability and confusion.
Testing Procedure
What Is a Normal B12 Count?
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If your doctor orders the vitamin B12 test for you, you may have your blood drawn in your doctor’s office, hospital lab, or in a separate lab in your community. The test is fast and simple, taking only minutes to complete. For this test, a technician will place a tourniquet around your arm to help her locate your veins. Next, she will obtain a sample of blood from a vein using a small needle. You will feel a prick when the needle is inserted. The blood sample is sealed into a tube and then sent to the lab to be tested.
- If your doctor orders the vitamin B12 test for you, you may have your blood drawn in your doctor’s office, hospital lab, or in a separate lab in your community.
- Next, she will obtain a sample of blood from a vein using a small needle.
Results
Depending on the speed of the lab and their current workload, your results may be available in a few hours to a day or two. Normally, a vitamin B12 value of less than 200 picograms per milliliter is considered a deficiency, although your doctor may have her own parameters for what requires treatment. For example, elderly patients may exhibit signs of deficiency when levels fall between 200 and 500 pg/mL.
Follow-Up
How Long Do Pap Smear Results Take?
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If your doctor discovers a B12 deficiency, you may be prescribed B12 supplements through injection or by oral supplement. To determine the effectiveness of your treatment, the test will be repeated two to three months after the supplementation begins. Your doctor will discuss the treatment plan with you and answer any questions you may have.
Related Articles
References
- Lab Tests Online: Vitamin B-12 and Folate Deficiency
- Lab Tests Online: Vitamin B-12 and Folate Deficiency-Test
- American Family Physician: Vitamin B-12 Deficiency
- Medline Plus: Anemia-B12 Deficiency
- New York Times: Vitamin B-12 Level
- Harvard Medical School Harvard Health Publishing. Time for more vitamin D. Updated September 2008.
- NIH Office of Dietary Supplements. Vitamin D fact sheet for health professionals. Updated August 7, 2019.
- American Association of Clinical Chemistry. Vitamin D tests. Updated October 15, 2019.
- National Heart, Lung, and Blood Institute. Blood tests.
- Kennel KA, Drake MT, Hurley DL. Vitamin D deficiency in adults: When to test and how to treat. Mayo Clin Proc. 2010;85(8):752-758. doi:10.4065/mcp.2010.0138.
- Veugelers PJ, Pham TM, Ekwaru JP. Optimal vitamin D supplementation doses that minimize the risk for both low and high serum 25-hydroxyvitamin D concentrations in the general population. Nutrients. 2015;7(12):10189–10208. doi:10.3390/nu7125527
- MedlinePlus. Vitamin D test. Updated April 15, 2019.
Writer Bio
Amber Canaan has a medical background as a registered nurse in labor and delivery and pediatric oncology. She began her writing career in 2005, focusing on pregnancy and health. Canaan has a degree in science from the Cabarrus College of Health Sciences and owns her own wellness consulting business.