title: Cobalamin absorption and serum homocysteine and methylmalonic acid in elderly subjects with low serum cobalamin.
abstract: We prospectively studied 41 consecutive elderly patients with serum cobalamin (vitamin B12) levels lower than 125 pmol/l. The protein-bound cobalamin absorption test (PBAT) was performed in 34 of them and in 27 selected elderly control patients. The lower decision limit was 0.18% and an abnormal test was detected in only 9 (26%) of the 34 patients with low serum cobalamin level. When the PBAT was compared to the Schilling (Dicopac method) test, a concordant result was found in 80%. Serum methylmalonic acid and/or total homocysteine concentrations were elevated in 75% (26/35) of the patients with low serum cobalamin levels but also in 30% (5/17) of the control patients. Of the 12 and 9 cobalamin-deficient patients with elevated serum levels of methylmalonic acid and homocysteine, normalization after cobalamin therapy was obtained in 11 and 5 respectively. In conclusion, determination of serum metabolites and their response to cobalamin therapy are a sensitive index of significant cobalamin deficiency and a useful means of distinguishing between cobalamin and folate deficiency. The PBAT offers little advantage over the Schilling test in diagnosing cobalamin malabsorption in elderly patients.
authors.affiliation: Department of Internal Medicine, University Hospitals K.U. Leuven, Belgium.
authors.forename: E
authors.initials: E
authors.lastname: Joosten
authors.forename: W
authors.initials: W
authors.lastname: Pelemans
authors.forename: P
authors.initials: P
authors.lastname: Devos
authors.forename: E
authors.initials: E
authors.lastname: Lesaffre
authors.forename: W
authors.initials: W
authors.lastname: Goossens
authors.forename: A
authors.initials: A
authors.lastname: Criel
authors.forename: R
authors.initials: R
authors.lastname: Verhaeghe
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D005260:Female; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D007408:Intestinal Absorption; D008286:Malabsorption Syndromes / Q000097:blood / Q000175:diagnosis; D008297:Male; D008764:Methylmalonic Acid / Q000097:blood*; D011446:Prospective Studies; D012016:Reference Values; D014805:Vitamin B 12 / Q000097:blood* / Q000378:metabolism*; D014806:Vitamin B 12 Deficiency / Q000097:blood* / Q000175:diagnosis
chemical_list: D006710:Homocysteine; D008764:Methylmalonic Acid; D014805:Vitamin B 12