Vitamin B12 (cobalamin)

What this test is

Vitamin B12 helps make red blood cells. It also keeps your nerves working well. Low B12 can cause tiredness or tingling. It can also cause memory, mood, or balance problems. It makes sense to check B12 if you have one of these signs. It also helps if you have a reason to be at risk. Risk factors include a vegan diet, or a mostly plant-based diet. They also include long-term use of metformin or a stomach-acid drug. Past stomach or gut surgery is another risk factor. If your first result is borderline, a second blood test can help. If B12 deficiency is confirmed, more tests can help find the cause. One of these checks how your stomach absorbs B12. Testing B12 with no sign and no risk factor is usually not needed.