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Vitamin B12 levels

I often see patients who tried to inject vitamin B12 by themselves, and it turns out their blood serum levels for B12 are exceeded.

They believe, that such a high level means they ingested too much of it with food. Of course, they believe that their bodies are perfectly saturated with B12 and that these stockpiles may last for long.

Is it true?

Let us take a look at some facts.

What are the best tests used to check for B12 deficiency? Sadly, checking the blood serum levels will not yield the expected answer. Even worse, it may mislead the patient.
An elevated level of B12 in blood serum, or hypercobalaminemia, is a common occurrence, and it usually accompanies tissue deficiencies of vitamin B12 or some liver and kidney diseases.
Transporting B12 in blood and tissue, as well as its uptake in the liver, requires the presence of transport particles, or transcobalamins (TCB) I and III, which bind around 80% of the circulating B12. Transcobalamin II, on the other hand, plays a vital part in transporting vitamin B12 to liver and tissues. Most of the cases of elevated B12 blood serum levels is associated with disorders of these peptides and not with its actual deficiency.

Elevated cobalamin blood serum levels are a result of three pathophysiological mechanisms:

  • Most common one is taking B12 supplements. During this supplementation the B12 level is usually raised and it declines on its own within a dozen or so days of stopping;
  • The second, little-researched increase is associated with release of physiological reserves (e.g. from damaged liver cells);
  • The third is transcobalamin production disorders (over- or underproduction, insufficient clearance) or synthesizing dysfunctional lipids, which do not bind the vitamin B12 correctly.

Additionally, in most of the laboratories, the measurements are still based on the level of cyanocobalamin, which not necessarily reflects the active metabolites of vitamin B properly.

Diagnosing clinically a B12 deficiency is challenging. For many years it was believed that the only certain symptom of B12 avitaminosis is megaloblastic anemia (anemia, in which the red blood cells reach a large size, but do not contain an adequate amount of hemoglobin).

Recently, however, much more attention has been given to neurological symptoms, which often may be the only symptom of cobalamin deficiency in tissues! These can be the so-called neural paraesthesia (e.g. strange sensations in the extremities), or cerebral symptoms: cognitive and memory problems, or loss of myelin sheathing of neurons, both cerebral and peripheral ones.
Lack of connection between the level of B12 in blood serum and its deficiency has made blood level testing for B12 levels far less meaningful.

Currently, in order to estimate deficiencies, the methylmalonic acid and homocysteine levels are measured, though the latter may be lower in cases of malnutrition, making it not fully reliable measurement as well.

Methylmalonic acid is currently the best measure for a functional B12 deficiency. Its lack leads to increased levels of methylamine by disrupting the conversion of methylmalonyl coenzyme A into succinyl coenzyme A using the methylmalonyl coenzyme A mutase enzyme.

A functional deficiency of B12 (high methylamine), along with its increased blood serum levels, is usually associated with liver cell disorders, such as hepatitis, cirrhosis, non-alcoholic fatty liver disease, and liver fibrosis.

Increased levels of B12 in blood serum may also signify diseases of kidneys or of the hematopoietic system.

When hypercobalaminemia is accompanied by heightened methylamine levels in urine, this signifies, paradoxically, its deficiencies in tissue, and a supplementation should be considered.
Very high levels of methylmalonic acid may suggest mitochondrial disorders, caused by vitamin B12 deficiencies, or methylation disorders. In these cases, supplementation should be implemented with utmost care—using adenosylcobalamin, hydroxocobalamin, and methylcobalamin.

Markers for methylmalonic acid in urine are a standard part of Organix and ONE tests. Among with other parameters, they help to estimate vitamin B12 requirements, considering liver overload and intestinal absorption disorders.

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