B vitamins are nutrients that your body needs to work well and stay healthy. There are eight different types. A vitamin B test checks the level of one or more B vitamins in a sample of your blood or urine (pee).

Vitamin B testing is used if you have symptoms that suggest you may not be getting enough of one or more B vitamins. For example, a vitamin B12 and folate test is often used for symptoms of certain types of anemia.

Source: MedlinePlus, U.S. National Library of Medicine