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What does it mean when your blood test shows High B12 Levels?
updated 2-15-2020

I've talked to many people who are told by their medical doctor that they found high levels of B12 in their blood test. They are thus reluctant to take a B vitamin formula designed to help build healthy nerves as it has B12 in it, or even just take a B supplement for their health.

In addition, it seems to be a big problem for a lot of people once their doctor tells them. They worry about what it could mean.

But, what does this actually mean?  

What other symptoms do you have?

High B12 levels in the blood can be the result of liver disease, kidney failure and blood cancers. There is also a condition where a person has too many white blood cells that causes high vitamin B12. These conditions, however, will all have other symptoms other than this blood test result, and your medical doctor will test if he suspects any of these.*

What else can it mean?

Blood tests are done with venous blood. This is the blood that comes after digestion and all the other bodily functions. It is on its way to dispose of a lot of things. One of them is things the body does not need. B12 is water-soluble, so the body can easily get rid of the B12 if it has too much. It will be in the blood.

So, why the excess B12.

1) Do you take B12 supplements with artificial B12? Many vitamins are made in a laboratory with synthetic ingredients. The body doesn't recognize it as food and it will no doubt be elminated from the body via the blood.

2) Do you eat processed foods which is fortified with B12? Again synthitic ingredients that the body doesn't recognize as food that will be gotten rid of via the blood.

3) Taking just B12 and no other B vitamins. They work together. B12 needs B9 to be activated, and much more. Here's an article on nerve health which explains this.

These can cause high levels of B12 in the blood.

A deficency of Vitamin B12?

A deficiency of vitamin B12, or a low B12 level, can contribute to a wide range of problems. General symptoms of vitamin B12 deficiency can include tiredness, weakness, abdominal pain, nausea, constipation, flatulence, reduction in appetite, and menstrual problems.

Extended periods of deficiency can eventually result in degeneration of nerves as the body needs it to build the myelin sheath (the outside of the nerve). Those who suffer from a vitamin B12 deficiency can have tingling sensations numbness, and burning feelings, weakness in the legs and problems walking. 

What happens when you have these low B12 level symptoms but the blood tests show high B12 levels?

Vitamin B12 does not accumulate to toxic levels. Consuming large quantities does not cause side effects or high levels in your system, whether you get it through food or from taking high-dose whole food B12 supplements.

What is another cause of blood tests showing high amounts of B12?

High serum B12 can be caused by a "functional" B12 deficiency. What does that mean?

In that condition, there is enough B12 going into the body, but the cells are not able to use it properly. This results in the body putting the B12 back in the blood. It builds up there bound to haptocorrin. Haptocorrin is a Vitamin B12 binding protein.

What happens when the body is not able to use the B12 at a cellular level?

High serum B12 per se is not harmful, but it indicates that there may be an issue with B12 utilization

One reason for this is that B12 from food and most supplements is the form cynocobalamine. In order for the body to utilize it, it must be converted to Methyl B 12 (or methylcobalamine). This conversion happens in the gut. The
intrinsic factor is necessary for this conversion. If a person doesn’t for any reason have sufficient intrinsic factor, this will not take place and the B12 will not be utilized. 

Intrinsic factor: Intrinsic factor is a protein secreted by the stomach that joins vitamin B-12 in the stomach and escorts it through the small intestine to be absorbed by your bloodstream. Without intrinsic factor, vitamin B-12 can't be absorbed and leaves your body as waste. 

Thus, high levels of B12 in a blood test can be a "functional" B12 deficiency. The intrinsic factor goes down with age, and thus as we age we are less likely to be able to absorb the B12 in our food and supplements.

For more information about a B12 Deficiency