Vitamin B12 is a water-soluble vitamin involved in the metabolism of every cell in the human body. This test determines the level of B12 in your blood.
Vitamin B12 active
Vitamin B12 performs several important functions in the body to keep the nervous system healthy. Deficiencies in vitamin B12 may cause extreme tiredness, a lack of energy, muscle weakness and problems with vision. Active B12 is the metabolically active portion of B12.