Vitamin B12 Blood Test
Vitamin B12 is bound in the blood to special transport molecules known as transcobalamins. Only vitamin B12 that is bound in this way can actually be utilised by the body. The holo-transcobalamin test (holo-TC test) measures only this biologically available vitamin B12.
The conventional serum blood test for total vitamin B12, which is still performed in many doctors' offices, also measures vitamin B12 that is not biologically available at all and therefore does not allow absolutely reliable statements about the actual vitamin B12 supply.
The holo-TC test, howver, gives a good indication of B12 levels that can reliably indicate even an impending deficiency.
Comparison between holo-TC test and MMA urine test
| Holo-TC | MMA Urine Test | |
|---|---|---|
| Material | Blood | Urine |
| Accuracy | Very high | High |
| Value | Directly bioavailable, circulating B12 | Indirect adenosylcobalamin in mitochondria |
| Results | Quantitative result shows total supply, no statement about real cellular activity | Shows cellular activity of one of the active vitamin B12 forms, quantitative results only possible to a very limited extent |
| Clinically Recognised | Yes | Yes |
Test for Vitamin B12 Supply
The holo-TC test is useful for determining the biologically available B12 supply and allows quantitative conclusions to be drawn about the state of the body's stores and the severity of any existing deficiency.
The holo-TC test reliably measures the vitamin B12 circulating in the blood, but does not allow any precise conclusions to be drawn about the cellular supply, which can be checked using the vitamin B12 urine test, for example. Optimal results can be achieved by combining both test methods.
