Diagnosis Vitamin B12 deficiency

mri image of brain in axial view showing “precontrast flair image”. note abnormal lesions (circled) in per ventricular area suggesting white matter pathology in vitamin b12 deficiency.



cervical spinal cord mri of subacute combined degeneration due deficit of b12. (a) midsagittal t2 weighted image shows linear hyperintensity in posterior portion of cervical tract of spinal cord (black arrows). (b) axial t2 weighted images reveal selective involvement of posterior columns.

serum b12 levels low in b12 deficiency, if other features of b12 deficiency present normal b12 further investigation warranted. 1 possible explanation normal b12 levels in b12 deficiency antibody interference in people high titres of intrinsic factor antibody. researchers propose current standard norms of vitamin b12 levels low. 1 japanese study states normal limits 500–1,300 pg/ml. range of vitamin b12 levels in humans considered normal: >300 pg/ml; moderate deficiency: 201–300 pg/ml; , severe deficiency: <201 pg/ml.

serum vitamin b12 tests results in pg/ml (picograms/milliliter) or pmol/l (picomoles/liter). laboratory reference ranges these units similar, since molecular weight of b12 approximately 1000, difference between ml , l. thus: 550 pg/ml = 400 pmol/l.

serum homocysteine , methylmalonic acid levels considered more reliable indicators of b12 deficiency concentration of b12 in blood. levels of these substances high in b12 deficiency , can helpful if diagnosis unclear.

routine monitoring of methylmalonic acid levels in urine option people may not getting enough dietary b12, rise in methylmalonic acid levels may indication of deficiency.

if nervous system damage suspected, b12 analysis in cerebrospinal fluid possible, though such invasive test should considered if blood testing inconclusive.

the schilling test has been largely supplanted tests antiparietal cell , intrinsic factor antibodies.

effect of folic acid

the national institutes of health has found large amounts of folic acid can mask damaging effects of vitamin b12 deficiency correcting megaloblastic anemia caused vitamin b12 deficiency without correcting neurological damage occurs , there indications high serum folate levels might not mask vitamin b12 deficiency, exacerbate anemia , worsen cognitive symptoms associated vitamin b12 deficiency . due fact in united states legislation has required enriched flour contain folic acid reduce cases of fetal neural-tube defects, consumers may ingesting more realize. counter masking effect of b12 deficiency nih recommends folic acid intake fortified food , supplements should not exceed 1,000 μg daily in healthy adults. importantly, b12 deficiency needs treated b12 repletion. limiting folic acid not counter irrevocable neurological damage caused untreated b12 deficiency.