The relationship between clinically confirmed cobalamin deficiency and serum methylmalonic acid.
Over a 1-year period, we examined 42 consecutive patients with low serum cobalamin levels detected by primary screening test (S-protein binder, RIA). In 31 patients (74%) clinical cobalamin deficiency was confirmed, whereas the remaining 11 patients (26%) were characterized clinically as non-cobalamin deficient. The serum methylmalonic acid level was higher than 0.34 mumol l-1 (3 SD above the mean in normal controls) in 30 of the 31 clinically characterized cobalamin-deficient subjects, and below this level in 10 of the 11 non-deficient patients. We conclude that the serum methylmalonic acid assay provides an appropriate means of discrimination between cobalamin deficiency and non-cobalamin deficiency (efficiency = 0.95), and we recommend that the assay be adopted as the standard test for diagnosis of tissue cobalamin deficiency.
Moelby
L
L
Department of Medical Haematology and Clinical Chemistry, Aalborg Hospital, Denmark.
Rasmussen
K
K
Jensen
M K
MK
Pedersen
K O
KO
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008764:Methylmalonic Acid / Q000097:blood*; D008875:Middle Aged; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014806:Vitamin B 12 Deficiency / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology
D008764:Methylmalonic Acid