Laboratory diagnosis of B12 deficiency
-A blood count showing the presence of a high mean corpuscular volume (MCV) may alert the physician to the presence of cobalamin deficiency. - Folate deficiency may lead to falsely low cobalamin levels. - In cases with a suspicious clinical picture and hematological alteration, but the serum cobalamin level is undetermined, the measurement of plasma homocysteine (normal 5-15 umol/L) and elevated plasma methyl malonate -MMA (normal <0.28 umol/L, very specific) can be considered as complementary tests because they are functional markers of the Cbls status in the organism. - Holotranscobalamin is the form of Cbls absorbed by cells to meet metabolic demand and laboratory testshave recently become available. - The presence of anti-intrinsic factor antibodies and anti-parietal cell antibodies should be investigated when there is no apparent cause for very low Cbls levels and may be present in pernicious anemia that can influence the results of tests based on competitive bindi...
