Food-bound B12 absorption and serum total homocysteine in patients with low serum B12 levels

Am J Hematol. 1998 Sep;59(1):42-5. doi: 10.1002/(sici)1096-8652(199809)59:1<42::aid-ajh8>;2-#.


This study was undertaken to determine whether measurements of serum total homocysteine (Hcys) and bound B12 absorption are useful in determining which patients with low- or low-normal levels of serum B12 are B12 deficient. In 40 patients with low or borderline serum levels of B12, food-bound B12 absorptions were determined using a body counter in an iron room, and were related to serum total Hcys levels. Food-bound B12 absorption was decreased in 16 patients and in an additional four, absorption of the free vitamin was also decreased. Homocysteine levels were elevated in four of the 16; in three of the four who had both decreased bound and free B12 absorptions, Hcys was elevated. If elevation of the Hcys level indicates tissue deficiency of B12, the 75% incidence of normal levels of Hcys in these patients with low food-bound B12 absorptions suggests the existence of a cohort of patients who may be at risk to develop, but have not yet developed, B12 deficiency. Only long term follow-up will reveal how many ultimately will become B12 deficient.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Blood Cell Count
  • Female
  • Folic Acid / blood
  • Food
  • Gastrins / blood
  • Homocysteine / blood*
  • Humans
  • Intestinal Absorption
  • Male
  • Middle Aged
  • Vitamin B 12 / blood
  • Vitamin B 12 / pharmacokinetics*
  • Vitamin B 12 Deficiency / blood*


  • Gastrins
  • Homocysteine
  • Folic Acid
  • Vitamin B 12