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The Significance of Subnormal Serum Vitamin B 12 Concentration in Older People: A Case Control Study
Author(s) -
Metz J.,
Bell A.H.,
Flicker L.,
Bottiglieri T.,
Ibrahim J.,
Seal E.,
Schultz D.,
Savoia H.,
McGrath K.M.
Publication year - 1996
Publication title -
journal of the american geriatrics society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.992
H-Index - 232
eISSN - 1532-5415
pISSN - 0002-8614
DOI - 10.1111/j.1532-5415.1996.tb01407.x
Subject(s) - medicine , vitamin b12 , homocysteine , clinical significance , creatinine , gastroenterology , endocrinology
OBJECTIVES: To determine the clinical significance of subnormal serum vitamin B 12 concentration in older people by comparing the hematological, neurological, and biochemical findings in patients with subnormal serum B 12 with a control group with normal B 12 levels. DESIGN: Clinical and laboratory assessment of hospital patients selected to represent a wide range of serum B 12 levels. SETTING: Patients in the medical wards of two hospitals, one a general hospital and the other a geriatric hospital. PARTICIPANTS: Ninety‐four older patients, 43 with subnormal (<150 pmol/L) and 51 with normal serum B 12 concentrations. MEASUREMENTS: Mini‐Mental State Examination, neurological score, full blood examination, mean neutrophil lobe count; serum B 12 , holotranscobalamin II, total homocysteine, folate, creatinine and gastrin red cell folate; parietal cell antibodies, intrinsic factor antibodies. RESULTS: Of all the measurements, only mean neutrophil lobe count and mean serum total homocysteine were significantly different in the low serum B 12 compared with the control group. There was a significant correlation between serum B 12 and homocysteine levels. Eighty‐eight percent of patients in the test group compared with 76% in the control group showed at least one of the following; elevated serum total homocysteine, neutrophil hypersegmentation, or elevated MCV. This overlap was much reduced when patients with borderline values for serum B 12 (150–250 pmol/L) were included in the low B 12 group. Most of the older subjects had little or no B 12 on transcobalamin II, irrespective of the serum B 12 level. CONCLUSION: Almost 90% of older patients with serum B 12 < 150 pmol/L show evidence of tissue vitamin B 12 deficiency. Deficiency becomes manifest in older patients at relatively higher concentrations of serum B 12 than in younger subjects, possibly because of lower levels of holotranscobalamin II in the older patients. J Am Geriatr Soc 44:1355–1361, 1996 .