The serum concentration of vitamin B12 may be falsely reported as elevated in a patient with multiple myeloma.
Patient selection: multiple myeloma with elevated serum vitamin B12 concentration reported
An elevated vitamin B12 is often not investigated. Questions may be raised if:
(1) there is evidence of functional vitamin B12 deficiency
(2) the elevation is persistent AND not explained by intake
Mechanism: formation of immune complexes which may bind vitamin B12 or interfere with assay
Workup may include analysis before and after treatment of the serum sample with polyethylene glycol (PEG), which precipitates the immune complexes.
(1) before PEG treatment the serum concentration of vitamin B12 is very high
(2) after PEG treatment the serum concentration of vitamin B12 is normal or low
Differential diagnosis:
(1) heterophile antibody
To read more or access our algorithms and calculators, please log in or register.
Specialty: Clinical Laboratory
