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45 years
I hv high level of vitamine b12 : 4460 pg/ml could u tell pls z risk nd z possible causes . Thk u
Oct 31, 2014

Dr. Zakia Dimassi Pediatrics
The transport of vitamin B12 (cobalamin) in the blood as well as its tissue and uptake into the liver require the presence of transcobalamins (TCBs), a group of proteins in the circulation that ensure the binding of circulating vitamin B12. TCB type II (TCB II) plays the predominant role in the key processes of tissue and liver uptake of vitamin B12.
Vitamin B12 functions as a coenzyme (assists enzymes) mainly involved in reactions leading to the formation of DNA and of that of certain amino acids.
It is currently considered that an increase in plasma levels of vitamin B12 may be an indicator of a problem in the function of vitamin B12, with clinical consequences similar to those of vitamin B12 deficiency. Indeed, an increase in the binding of vitamin B12 leads to a potential decline in its attachment to TCB II, so B12 cannot enter the cells. B12 functional deficiency may also occur if there is liver damage and the liver cannot take up B12 from the serum, and/or by leakage of total vitamin B12 from the liver tissue into the plasma.

Causes of elevated Vit B12 include:
Excess vitamin B12 intake
1. The ingestion of multivitamin complex tablets containing vitamin B12.
2. Parenteral administration (injection) of vitamin B12, mostly administered in the treatment of a documented vitamin deficiency. In this regard, it should be reminded that the injectable B12 is decreasingly recommended in the majority of etiologies of vitamin B12 deficiency and that, as mentioned earlier, oral treatment has been found to be both effective and sufficient.
High serum cobalamin and solid tumors
The carcinomas most frequently involved are hepatocellular carcinoma (HCC) and secondary liver tumors, breast cancer, colon cancer, cancer of the stomach and pancreatic tumors.
High serum cobalamin and blood disorders
High serum cobalamin is frequently observed in malignant blood diseases including chronic myelomonocytic leukemia and primary hypereosinophilic syndrome (HES), myelodysplastic syndromes and acute leukemias (ALs).
High serum cobalamin and liver diseases
Since the liver plays a major role in the metabolism of cobalamin, acute and chronic liver diseases, regardless of their etiology, may lead to high serum cobalamin.
Acute hepatitis can be associated by high serum cobalamin in 25–40% of cases.
In liver cirrhosis, high serum cobalamin can be found five times above the upper limit.

Other causes of high serum cobalamin
The role of the kidney in the metabolism of vitamin B12 is currently well accepted. Kidney failure is among the causes to look for when confronted with high serum cobalamin.
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