Age and Ageing Advance Access originally published online on December 21, 2006
Age and Ageing 2007 36(2):177-183; doi:10.1093/ageing/afl150
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Vitamin B12 deficiency in the aged: a population-based study
1 Department of Clinical Chemistry, University of Turku, Turku, Finland
2 TYKSLAB, Hospital District of Southwest Finland, Turku, Finland
3 Mehiläinen Oy, Turku, Finland
4 Institute of Clinical Medicine, Family Medicine, University of Turku, Turku, Finland
5 Härkätie Health Centre, Lieto, Finland
6 Pori Health Centre, Pori, Finland
7 Unit of Family Medicine, Turku University Central Hospital, Turku, Finland
8 Satakunta Central Hospital, Pori, Finland
Address correspondence to: S. Loikas. Fax: 358-2-2613920. Email: sailalo{at}utu.fi
Background: vitamin B12 deficiency is common in the aged, but it is controversial whether only some risk groups should be investigated instead of screening the entire aged population.
Objectives: to describe the prevalence of vitamin B12 deficiency in the Finnish aged, and to find out if the subjects especially prone to vitamin B12 deficiency could be identified by the risk factors or clinical correlates.
Design: a cross-sectional, population-based study of 1048 aged subjects (age 65–100 years) was carried out. Data on lifestyle factors and clinical conditions were collected, physical examinations were conducted and laboratory variables related to vitamin B12 were measured.
Results: vitamin B12 deficiency had been previously diagnosed in 27 (2.6%) subjects, and a laboratory diagnosis (total vitamin B12 <150 pmol/l, or total vitamin B12 150–250 pmol/l and holotranscobalamin 
37 pmol/l and homocysteine 
15 µmol/l) was made for 97 (9.5%) subjects. Low serum total vitamin B12 (<150 pmol/l) was observed in 6.1% and borderline total vitamin B12 (150–250 pmol/l) in 32% of the subjects. Male gender (OR 1.9, 95% CI 1.2–2.9), age 75 (OR 2.2, 95% CI 1.4–3.4) and refraining from milk products (OR 2.3, 95% CI 1.2–4.4) increased the probability for vitamin B12 deficiency. Anaemia (OR 1.3, 95% CI 0.7–2.3) or macrocytosis (OR 1.2, 95% CI 0.6–2.7) did not predict vitamin B12 deficiency.
Conclusion: undiagnosed vitamin B12 deficiency is remarkably common in the aged, but no specific risk group for screening can be identified. Thus, biochemical screening of unselected aged population is justified. General practitioners play a key role in diagnosing early vitamin B12 deficiency.
Keywords: vitamin B12, holotranscobalamin, vitamin B12 deficiency, aged, screening, cohort study
Received 13 April 2006; accepted in revised form 31 October 2006.