The relationship between clinically confirmed cobalamin deficiency and serum methylmalonic acid

J Intern Med. 1990 Oct;228(4):373-8. doi: 10.1111/j.1365-2796.1990.tb00248.x.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Female
  • Humans
  • Male
  • Methylmalonic Acid / blood*
  • Middle Aged
  • Prospective Studies
  • Sensitivity and Specificity
  • Vitamin B 12 Deficiency / blood*
  • Vitamin B 12 Deficiency / diagnosis
  • Vitamin B 12 Deficiency / epidemiology


  • Methylmalonic Acid