American Association for Clinical Chemistry
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NACB - Scientific Shorts
NACB - Scientific Shorts (formerly NACB Blog)
By William E. Winter, MD, DABCC, FACB
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This case has been edited so that the patient is de-identified. The patient was a prepubertal girl with a learning and social disability for which she was receiving non-traditional treatments. Her vitamin B12 level was found to be greater than 50,000 pg/mL with an upper limit of the reference interval being 1200 pg/mL. How could her vitamin B12 level be so high and what effects could this have on the child?

Response: For unclear reasons, the child was receiving more than 20 mg of vitamin B12 injected at least 3 times per week (note: there is no medicinally accepted reason to treat learning and social disability with vitamin B12). While vitamin B12 is not generally toxic even at very high concentrations, high B12 levels can be seen in a number of pathologic conditions. The list below provides the upper limits of vitamin B12 levels reported in a number of pathologic conditions (1):

                                             Highest vitamin B12 concentrations
Hypereosinophilia syndrome     10,000 - 25,000 pmol/L*
Metastatic liver disease                 "           "        "
Acute hepatitis                         5,000 - 10,000 pmol/L
Cirrhosis                                      "           "        "
Hepatocellular carcinoma               "           "       "
Chronic myelogenous leukemia
Cystic fibrosis                            2,500 - 5,000 pmol/L
Polycythemia vera                      1,000 - 2,500 pmol/L

*To convert SI units (pmol/L) to English units (pg/mL) divide pmol/L by 0.738.

 

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About the Author
William E. Winter, MD, DABCC, FACB
William E. Winter, MD, DABCC, FACB 
 

Reference

1. Ermensa AAM, Vlasveldb LT, Lindemansc J. Significance of elevated cobalamin (vitamin B12) levels in blood. Clinical Biochemistry 36 (2003) 585–590