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Company
Nutrition & Vitamins
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Currently under review
Pending specialist review and validation.
The Vitamin B12 Level test measures the amount of cobalamin circulating in your blood. Vitamin B12 helps your body make healthy red blood cells, supports proper nerve function, and is needed for DNA production. Your body does not make this vitamin on its own, so you must get it from food or supplements, and it is absorbed in the small intestine with help from a protein made in the stomach called intrinsic factor.
This test is performed on a blood sample from a vein. Clinicians often interpret it alongside your symptoms and other labs such as a complete blood count, folate, or markers that reflect how well your cells are using B12, to build a clearer picture of your nutritional and absorption status.
Low Vitamin B12 can cause anemia, fatigue, tingling or numbness, trouble with balance, memory or mood changes, and soreness of the tongue. Identifying a problem early can prevent lasting nerve issues and improve energy and thinking. Your clinician may order this test if you have symptoms, abnormal blood counts, or conditions that affect the stomach or intestines.
People at higher risk include those who avoid animal products without reliable supplementation, older adults, individuals with stomach or intestinal disorders or surgery, and people taking certain medicines that lower absorption. The test is also used to monitor how well treatment or supplementation is working for you.
If your level is lower than expected, your clinician will consider causes such as not getting enough from your diet, trouble absorbing the vitamin, or autoimmune problems that block absorption. They may recommend supplements, dietary changes, or additional tests that look for how your body is using B12 or check for specific antibodies. Borderline results sometimes need confirmation with follow up testing before starting long term therapy.
Higher than expected levels can happen with recent supplements or injections, and sometimes with liver or blood conditions. Be sure to tell your clinician about all vitamins and medicines you take. Your result will be interpreted together with your symptoms, medical history, and other tests to decide on the safest next steps.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
Taking B12 pills or receiving a recent injection can temporarily raise the measured level in blood and may mask an underlying absorption problem. Tell your clinician what you took and when.
Metformin, proton pump inhibitors, and some acid reducing medicines can lower B12 absorption over time. Long term use may warrant testing and, if needed, supplementation.
Pernicious anemia, celiac disease, inflammatory bowel disease, bacterial overgrowth, and prior stomach or intestinal surgery can reduce absorption and lead to low levels.
Very high biotin intake can interfere with some immunoassays and may give misleading results. Avoid high dose biotin for at least a day before testing unless your clinician advises otherwise.
Older adults and people who eat little or no animal products are at higher risk of low B12. Fortified foods or supplements can help maintain adequate intake when needed.
Needs for many nutrients change during pregnancy and lactation. Your clinician may check B12 if you have anemia, neurologic symptoms, or limited intake to support you and your baby.
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